The concept of a Hausdoeff dimension, so-called fractal dimension, was proposed by Mandelbrot. The application of the fractal dimension provides an effective technique to investigate an irregular morphology. To evaluate the applicability of the fractal analysis in quantitative fractography, a typical fatigue striation formed under several stress ratio on aluminum alloy were analyzed. Fracture surface topography were measured by using an AFM. The fractal dimension used in this study was the correlation dimension. The chaoticity of fracture surface was also evaluated. The results that have been obtained are as follows: (1) Because the maximum Lyapunov exponent becomes a positive number, it is believed that the striation are chaotic. (2) As well as the correlation dimension, it is possible that the maximum Lyapunov exponent becomes a candidate for quantifying the striation topography. (3) Phase diagram are also useful to discriminate the difference in fracture surface.

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An investigation has been carried out concerning the influence of stress waveform and wet environment on the fatigue fracture behavior of aramid single fiber. The aramid fiber used in this study was Kevlar 49 manufactured by Du Pont. Tension-tension fatigue tests were conducted under inusoidal, negative pulse and positive pulse waveforms for the fiber preconditioned in laboratory air and in wet air (RH 98±2%, 20±2℃). The fatigue strength of Kevlar 49 tested in wet air was lower than that in laboratory air, and the fatigue strength in air under negative pulse waveform was higher than those under other two waveforms. The fiber broke with fiber splitting for the quasistatic tensile tests and the fatigue tests under sinusoidal and positive pulse waveforms in air. In contrast with these, the fiber broke with transverse crack when the specimen was subjected to the negative pulse waveform, with longer fatigue life. This final fracture morphology under negative pulse waveform corresponded to the transverse undulations that were observed by atomic force microscope(AFM).

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A micro-indentation test is useful for evaluating mechanical properties of a microstructure. However, because the measurement values are very small, there are some significant error factors. The influences of some factors, a compliance of a measurement device, a tip shape of an indenter, a contact area change during unloading, a change of an indentation shape, a work-hardened layer, a strain rate, a surface roughness and a change of a temperature were investigated with experiments and 2- or 3-dimensional finite element analyses. The work-hardened surface which was made by mechanical polishing changes the properties of a non-worked material. It is important to improve Young's modulus and a hardness estimation by changing the calculated value to the measured value. In order to evaluate properties of a material accurately, an electropolishing is needed after mechanical polishing. The strain rate expands the hardness and changes Young's modulus. The surface roughness makes the measurement value dispersed because the first contact height is changed variously. Measuring Young's modulus is more sensitive to the change of the temperature than measuring the hardness.

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A new technique for producing a sharp pre-crack between a thin film and a substrate is developed utilizing the difference in interface strength. This technique is applied to a sputtered copper (Cu) thin film on silicon (Si) substrate. A vacuum-evaporated Cu thin film, which has poor adhesion to Si, is inserted between the sputtered Cu thin film and the Si substrate as a release layer. The release layer debonds from the Si substrate at very low load, and the process successfully introduces the sharp pre-crack along the interface. Using the specimen, the interface fracture toughness test is conducted and the critical strain energy release rate, G_C, is evaluated as about 1.78 J/m^2 for the sputtered Cu/Si interface.

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An experimental method for evaluating interface strength of a small dot on a substrate is developed using a modified Atomic Force Microscopy (AFM). This technique is applied to a tungsten (W) dot of micrometer size on a silicon (Si) substrate. A diamond tip is dragged horizontally along the Si surface and the load is applied to the side edge of the W dot under a constant displacement rate. The lateral as well as the vertical load and displacement are continuously monitored during the test. After the tip hits the W dot, the lateral load, F_l, increases in almost proportion to the lateral displacement, δ_l. The W dot is abruptly separated from the substrate along the interface. The apparent fracture energy of the interface, E_d, is successfully evaluated.

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This paper deals with the evaluation method of the local work affected layer based on the magnetic domain analysis using a magnetic force microscope (MFM). The fine maze magnetic domain pattern is observed on the lapped ferrite (111) plane. The maze domain pattern becomes coarser by increasing the etched depth of affected surface layer. The area percentage of magnetic domain pattern in the whole lapped surface decreases with an increase of the etched depth and the magnetic domain pattern disappears when the etched depth exceeds about 1μm. This critical value in the etched depth is almost equal to the work affected layer depth, evaluated from electron diffraction analysis. These results show that the magnetic domain imaging method by the MFM becomes a useful technique for evaluating the local work affected layer.

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In order to investigate the tribological properties of alloy carbides in the die steel, a series of nanoscratching tests for chromium carbides (Cr_7C_3 carbide) containing in the cold work die steel SKD11 has been carried out using an atomic force microscope (AFM) having a two-axis force/displacement transducer. Reduced modulus of Cr_7C_3 is about 1.7 times higher than that of matrix and nanohardness of Cr_7C_3 is about 2.3 times higher than that of matrix. A reproducible groove is formed on Cr_7C_3 when the normal force exceeds 45 PN, while the minimum normal force in which the reproducible groove is formed on matrix is 15 PN. At a normal force of 100 PN, the groove formed on matrix is about 15 times deeper compared with that formed on Cr_7C_3 . When the grooves with the same depth are formed on Cr_7C_3 and matrix, a ratio of force components on Cr_7C_3 is lower than that of matrix. Thus wear characteristics of Cr_7C_3 carbide have been independently evaluated by means of the nanoscratching with AFM.

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AFM(Atomic Force Microscopy) provides three-dimensional digitized images of surface morphological features and thus is one of the most useful tools that analyze the mechanisms of fatigue. AFM is used to study the surface slip features in polycrystalline low carbon steels tested under the cyclic load at high cycle fatigue range. In general, excluding the case of intensely high stress concentration or high strength materials which have high sensitivity to defects, following the formation of extrusions and intrusions along persistent slip bands (PSBs) occurred at a free surface, a stage I fatigue crack initiates. For the improvement in the fatigue strength, to reveal the difference of slip features depending on the strengthening method, non-hardening steel (base), solid-solution hardening steel by each of Ni/Si/Cu (Ni-s, Si-s, Cu-s) and precipitation hardening steel by Cu (Cu-p) are submitted. The all steels have ferritic-pearlitic structures with an average grain size of about 45 μm. The fatigue specimens are plates with 1mm thick. Strain controlled fatigue tests at constant strain that yielded fatigue lives of 10^5-10^6 cycle and a stress ratio R=-1 were performed on the out-plane bending machine. Interrupting the fatigue test properly, periodic AFM observations carried out on original specimens. AFM discriminated difference of slip features. On base steel slip bands were observed early at 10^3 cycle (N/N_f=0.5%) and distinct extrusions and intrusions grew tall linearly. Then the growth was saturated at 10^4 range, but the crack had not been generated. Much more damage was required for the crack initiation. The growth rate was about 0.02 nm/cycle and the highest extrusion was about 600 nm high. The crack initiation did not occur only at grown-up intrusions but also at root of extrusions. On Ni-s steel a distinct intrusion didn't occur, but whole roughness increased. On Si-s steel some low and planar stairs-like slips generated, because of prevention of cross slips by Si. On Cu-s steel rare and sharp extrusions occurred. On Cu-p steel extrusions ion was late at 10^4 range.

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A dynamic operation of atomic force microscopy (AFM) provides images depending on the elasticity of sample surface in addition to the topography. A resonant frequency of an AFM probe, i.e., a cantilever equipped with a force-sensor tip, depends on the contact stiffness between a sample and a tip. However, poor sensitivity often confronts us for stiff sample, e.g., ceramics and metals. We have developed a special cantilever with its mass concentrated as a way of enhancing the sensitivity to contact stiffness. A tungsten particle was employed as a concentrated mass, which is adhesively attached to the free end of a commercially available rectangular cantilever made of silicon. Measurements of the spectra and the elemental beam theory proved that the attachment of a concentrated mass provides a sufficient sensitivity even for stiff materials. We have also demonstrated a powerfulness of our cantilever in quantitative evaluation of local elasticity. In this study, we discuss an imaging technique for the mass-concentrating cantilever, and shows examples of elastic images, whose contrast is based on the elastic differences of the surface structure. So-called slope detection for contact resonance works well and produces high contrast images of elasticity for several nano-structured materials.

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The deformation behaviour of metal: Ti (as reference material), glass: Pyrex and soda-lime, and ceramics: ZrO_2 and Al_2O_3 have been studied under repeating nanoindentation with fixed maximum and minimum loads and 5 mN/s loading speed for 10 cycles. Three characteristics of deformation behaviour i.e. forward/backward deviation and hysteresis loop of load-displacement curves and pile-up of the material around the indent mark are compared to each other. In titanium, forward deviation, looping and pile-up were observed. In Pyrex glass, forward deviation without looping and no ^piling-up were observed. In soda-lime glass, backward deviation, comparatively big loops and pile-up were observed at higher loads. The existence of residual stress is the primary reason for backward deviation. The reason for the looping is the difference in the stored and released strain energy which corresponds to the random distorted movement of the amorphous structured glass molecules. Backward deviation was observed in as-supplied zirconia but forward deviation in polished zirconia. In both the cases no looping occurred but pile-up appeared. In alumina, forward deviation without looping and pile-up were observed. Thus deformation behaviour under repeating nanoindentation is strongly affected by material structure and surface condition.

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Martensitic transformation and degradation characteristics for ferromagnetic shape memory alloy Fe-Pd were investigated by the developed hybrid nano-characterization technique using atomic force microscopy and magnetic force microscopy. Under loading cycles, degradation was detected both in AFM and MFM images before martensitic transformation temperatures changed. In AFM images surface topography became flat and in MFM images magnetic domain structures became unfocused with increasing number of cycles. Under thermal cycles, degradation was also detected in MFM images with increasing number of cycles. Then it was concluded that hybrid nano-characterization was very high sensitive technique to detect degradation under loading and thermal cycles for ferromagnetic shape memory alloy.

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The true relief arising on the surface of cyclically strained materials has been assessed using atomic force microscopy and high resolution scanning electron microscopy. Characteristic features of the surface relief are well-defined persistent slip markings consisting of extrusions and intrusions. The shape of extrusions and intrusions can be obtained by combination of both methods. The growth of extrusions during fatigue life was reported for austenitic and ferritic stainless steels. The comparison of the experimental data with the predictions of the various models of fatigue crack nucleation allows to conclude that the realistic models are based on a continuous redistribution of matter leading to extrusion and intrusion formation.

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PMMA/silica nano composite was innovated by the sol-gel process polymerization from methyl methacrylate (MMA) and tetraethyl orthosilicate (TEOS) with hydroxypropyl acrylate (HPA) as a coupling agent. It has been investigated that an acid catalyst or a catalyst-less condition affects the phase structure of PMMA/silica nano composite by X-ray photoelectron spectroscopy (XPS). Acid catalyst condition is controlled to be pH=4 by using hydrochloric acid. The XPS measurement was characterized by the ratio Si2p (Si-O-Si)/Si2p[(Si-O-C)+(.Si-O-Si). The results suggested the ratio of the covalent bonds between the organic component and the inorganic component (Si-O-C) under acid catalyst is higher than that under the catalyst-less condition.

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Slip-band formation and crack-initiation processes in α-brass under cyclic shear stress were examined by means of atomic force microscopy (AFM), and the slip-direction was identified with electron back scattering pattern method (EBSP). From AFM observations, it was found that slip-bands were not always formed along the maximum resolved shear stress directions, and slip-systems could be activated in the direction whose angles from the surface were larger than 22°. The depth of an intrusion increased linearly with the logarithm of the number of cycles, and the increasing rate of the intrusion depth drastically increased with crack initiation. By combining the intrusion depth and the slip direction, those were measured with AFM and EBSP, respectively, the value of slip distance could be evaluated, and the critical values of the slip distance for the initiation of transgranular crack was found to be constant for all crack initiation sites, while the intrusion depth was not constant. The critical value of the slip distance for cyclic shear stress (torsion) was identical for cyclic normal stress (bending). A unique relationship between shear stress amplitude in the actual slip direction and number of cycles to failure was obtained for cyclic torsion and bending loadings.

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EBSD and AFM have been combined to study slip bands produced at the surface of a 316L austenitic stainless steel tested in the low cycle fatigue range. EBSD investigations allow activated slip systems to be identified. AFM measurements permit to characterize the height profile of extrusions at a nanometric scale. Their coupling in the same deformed areas has permitted to analyze in details the morphology of extrusions in relation with the local crystallographic configuration. A special attention has been paid on the inclination of slip bands.

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Ultrafine-grained specimens with the average grain size of less than 2μm and medium-grained specimens were prepared from steel plates produced by an advanced thermo-mechanical control process. The smooth specimens were fatigued under cyclic axial tension compression at room temperature in air. The fatigue crack initiation process was investigated by atomic force microscopy and crystallographic orientation image microscope by EBSP. The results show that fatigue cracks initiated from the simple slip lines in the medium-grained specimens. On the other hand, in the ultrafine-grained specimens, complex slip deformation was formed in the vicinity of the grain boundaries prior to the initiation of fatigue cracks. Fatigue cracks were nucleated at the boundary between the grains with the concentrated complex slip deformation. The crystallographic analysis by EBSP revealed that the complex slip deformation was formed by the cross slip of active slip systems with the largest Schmid factors.

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We developed a method for measuring the fracture toughness of single crystal silicon thin film. We prepared single-edge-notched specimen of 5μm thickness on (110) wafer, with tensile irection in <110> orientation. Our on-chip test device eliminates the troublesome of gripping fragile specimen. The measured average fracture toughness was 1.65 MPa・m^<1/2>, with scatter. It is somewhat higher than, but comparable to the value of bulk silicon. The scanning electron microscope (SEM) observation shows that the fracture preferred occur on the (111) cleavage plane.

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Experimental investigations were carried out to characterize fracture and fatigue behaviours of an actuator piezoelectric ceramic under the combined loading of a high electric field and a mechanical stress. Results show that there exists a strong anisotropic effect on fracture toughness and electric field induced fatigue crack growth in polarized PZT. It is found that the surface fracture toughness in the orien -tation parallel to the polarization direction is much higher than that in the transverse orientation. Under a positive electric field, increasing electric field intensity reduces the fracture toughness in the transverse orientation but enhances that in the parallel orientation. However, the reverse is true under a negative electric field. Low electric field intensity does not result in fatigue crack growth in PZT. For a relatively high applied electric field, the cracks initially grow fast and then are arrested. This result is very significant for the long-term durability of PZT actuators.

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Feasibility on the application of discontinuous carbon fiber reinforced polymers to microscale structures was studied on the basis of classical theories and some experiments. In addition, fabrication of micro-parts with the discontinuous carbon fiber reinforced polymers was tried using the photopolymerization process. The theoretical prediction suggested the feasiblity on the application of discontinuous carbon fiber reinforced polymers to microscale structures. The experimental results showed that the elastic modulus, fracture toughness and dimensional stability could be largely improved by the reinforcement with discontinuous carbon fibers, though the tensile strength could not be improved in case of the material system used in the present work. The fabrication of a micro-gear of a dicontinuous carbon fiber reinforced polymer did not succeed completely owing to the limitation of the current system.

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This paper presents an advanced technique to determine all independent elastic constants C_<ij> of thin films. Many polycrystalline films exhibit elastic anisotropy between the film-growth direction and in-plane direction, and macroscopically possess five independent elastic constants; they are denoted by C_<11>, C_<33>, C_<13>, C_<44>, and C_<66> when the x_3 axis is chosen along the film-growth direction. All of C_<ij> of thin film affect the mechanical resonance frequencies of a film/substrate specimen. Measuring them permits us to determine the film C_<ij> with known density, dimensions, and the elastic constants of the substrate. It is necessary to measure the resonance frequencies with a high accuracy, because the contributions of the film C_<ij> to the resonance frequencies are normally small. We made this possible using the piezoelectric tripod, which consists of two piezoelectric pinducers and a supporting pin. The specimen is held on the tripod and only the specimen weight makes the acoustic coupling. This weak but stable coupling measures the resonance frequencies with a high accuracy. We applied our technique to copper thin films and found anisotropy between C_<11> and C_<33>.

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The crack propagation behavior of hcp crystal has been simulated by molecular dynamics method using Lennard-Jones type potential. A crack was introduced to model crystals which have free surfaces. The size of the model was 13nm X 12nm X 4.6nm and 42000 atoms were included in the model. The crack was propagated by two type of loading method. In the case of applying mode I displacement to boundary atoms, cracks were propagated as brittle manner. It was found that there are two type of fracture mode existed at crack tip in mode I simulation and "Shear lip" is formed on the crack surface. Width of the shear lip was about 1.1 nm. The yield strength of the model crystal was 4.0GPa, which is estimated by tensile test of the model crystal without a notch. Size of the plastic zone at crack tip was estimated from above yield strength and the value of crack length by using Irwin's theory. The size is similar to the width of the shear lip. When model crystals with 8000 atoms was applied tensile strain, A definite dependence of crystallographic orientation on crack propagation behavior was obtained. In the case of model crystals with initial notch plane and direction were (101^^-0), [2^^-110], the crack propagated parallel to notch plane and two sets of prismatic slips were occurred at the crack tip in both crystals. Therefore, the crack in these crystals are deduced to extend by alternating shear on two intersecting {101^^-0}<12^^-10> prismatic slip systems. In a model crystal with (0001), [12^^-10] initial crack, {101^^-1} first order pyramidal slip and {101^^-2} twin occurred at crack tip. In the model crystal with (101^^-0)[0001] initial crack, the crack propagate parallel to initial crack plane with some basal slips in front of the crack.

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The effects of sputtering gas (Ar gas) pressure on the growth and the structure of 0.3 to 0.4 μm thick Ti thin film membranes microfabricated by magnetron sputtering were studied using transmission electron microscopy. Sputtering gas pressure was varied from 0.2 Pa to 2.0 Pa. The deposited Ti films exhibited very fine structures. The Ti films deposited at 0.2 to 1.1 Pa had hexagonal close-packed structures with the preferred orientation. On the other hand, the Ti films deposited at 2.0 Pa appeared to be a mixture of a random hexagonal close-packed structure and a cubic structure. The Ti films deposited at lower Ar gas pressures had dense structures with smooth flat surfaces, however, and the rough surfaces of the Ti films were promoted by elevated Ar gas pressures. Shadowing played a very important role in the coating growth of the Ti films. The lower tensile strength values of the Ti films deposited at higher Ar gas pressures can be explained in terms of shadowing.

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Recently, because the micro-machine is noticed and electronic equipments are made much lighter and smaller, the demand for micro materials is increasing. The researches for elucidating the mechanical properties of micro materials, which are called micro testing, have been carried out and it has been turned out that the micro materials are different from the bulk materials on the mechanical properties. However the mechanical properties data of the micro materials obviously run short and the evaluation method of micro materials is different according to the researcher. Therefore, the establishment of the test method for the micro materials is very necessary. The purpose of this study is to establish a test method of tensile strength for the micro materials and to investigate the mechanical properties of the micro materials. Then, the tensile strength tests of SUS304 thin sheet were carried out using micro force testing system (MTS Tytron250), and the effect of the thickness, the width and the shape of specimen on mechanical properties was investigated. As the results of experiment, it was seen that Young's modulus E decreased with increasing the thickness, and that the specimens of 80, 500 and 1000μm thickness differed from the specimens of 20μm thickness in the mode of plastic deformation, the correlation of tensile strength σ_B and thickness, and correlation of the fracture elongation ε_f and thickness.

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Over the past ten years a variety of techniques for characterizing the fatigue behavior of structural films have emerged. In particular, micromachined resonant fatigue characterization structures have been used to evaluate the stress-life fatigue behavior of thin films. In this work we will first review the design, testing, and analysis of micromachined fatigue characterization resonators. Subsequent discussion will focus on how resonant-loaded fatigue characterization structures were used to evaluate the high-cycle fatigue behavior of silicon films commonly used in microelectromechanical systems (MEMS). Although bulk silicon is not known to be susceptible to cyclic fatigue, micron-scale structures made from mono and polycrystalline silicon films display "metal-like" stress-life (S/N) fatigue behavior in room temperature air environments. Fatigue lives in excess of 10^<11> cycles have been observed at high frequency (〜40 kHz), fully-reversed stress amplitudes as low as half the fracture strength. Stress-life fatigue, transmission electron microscopy, infrared microscopy, and numerical models were used to establish that the mechanism of the apparent fatigue failure of thin-film silicon involves the sequential oxidation and environmentally-assisted crack growth solely within the native silica layer, a process termed "reaction-layer fatigue". Only thin films are susceptible to such a failure mechanism because the critical crack size for catastrophic failure of the entire silicon structure can be exceeded by a crack solely within the native oxide layer. The growth of the oxide layer and the environmentally-assisted initiation of cracks under cyclic loading conditions are discussed in detail. Furthermore, the importance of interfacial fracture mechanics solutions and the synergism of the oxidation and cracking processes are described.

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This research focuses on revealing mechanical properties of diamond-like carbon (DLC) films for surface modification in MEMS. New compact tensile tester operating in an atomic force microscope (AFM) was developed for characterization of Young's modulus, Poisson's ratio and fracture strength of DLC films. The DLC films having sub-micron thickness from 0.2μm to 0.5μm were deposited onto microscale single crystal silicon (SCS) specimens by PE-CVD method of the hot cathode PIG discharge type. Young's moduli of the DLC films in AFM tensile tests ranged from 99 GPa to 112 GPa. AFM tensile tests and nano-indentation tests revealed that Poisson's ratio of DLC films ranged from 0.27 to 0.40. Fracture stress of the films also exhibited from 0.5 GPa to 1.1 GPa, which depended on the film thickness and deposition condition. SEM observations of fracture surfaces suggested that the fracture initiation of DLC/SCS specimens was induced at the boundary between the film and SCS substrate.

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Nano materials are being increasingly used in industrial applications as structural components or functional devices. Mechanical reliability is one of the critical issues with respect to these materials. This paper gives an overview of the different research projects relative to the field of surface nanocrystallization (SNC) of metallic materials during last years. Different patented routes of processing of the SMAT (Surface Mechanical Attrition Treatment) and their effect on the mechanical behavior will be presented.

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Young's modulus of polysilicon thin film was measured by means of a tensile tester equipped with an electrostatic force grip system. Images of gauge marks on a specimen were captured by a high-speed digital CCD camera and the tensile strain was calculated from the images. The linear stress-strain curve was obtained and Young's modulus measured. The polysilicon specimens were 1.7μm thick, 20 and 50μm wide, and 100 and 500μm in gauge length. The mean Young's modulus ranged from 163〜174 GPa, which agreed with the theoretical and values measured using the bulge method. The resolution of the strain measurement was less than 50 nm, and the comparison to the differential methods shows the image analysis system had smaller deviations.

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Recently Bradby et al. in a series of papers have investigated the mechanical properties of a range of elemental (Si and Ge) and a range of compound semiconductors (GaAs, InP, GaN, ZnO) using nano-indentation and associated cross-sectional TEM. In all instances cross-sections were made of impressions at various indentation loads using focused ion beam milling (FIB). Indentations were primarily made with a small spherical tipped indenter, which enabled the transition from elastic to elastic-plastic behaviour to be quantified. Complimentary observations of the residual impressions with AFM and Raman micro-probe spectroscopy were made as well as some electrical conductivity measurements during the indentation cycle. It was observed that only in the case of silicon was definitive evidence found for a pressure induced phase transformation beneath the indenter. In all other materials deformation occurred by classic plastic deformation, namely; dislocation motion and twinning. In the case of silicon it was found that the resultant phase transformation observed in TEM sections from beneath the indenter depended strongly on the unloading rate. More recent studies by the same authors have also simultaneously investigated the electrical resistivity during nano-indentation to quantify the onset of phase changes.

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Techniques and procedures are presented for measuring strain directly on thin-film polysilicon at high temperatures. Narrow platinum lines are deposited 250μm apart on tensile specimens that are 3.5μm thick. Strain is measured by laser-based interferometry at temperatures up to 600℃. Specimens that are 600μm wide are heated resistively, and narrower specimens (50μm wide) are heated in a windowed furnace. Measurements of the coefficient of thermal expansion, Young's modulus, stress-strain, and creep behavior are presented.

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High-density nanocrystalline (n-) gold with almost the full density is prepared by a gas-deposition method. The Young's modulus of the high-density n-Au is comparable with that of conventional polycrystalline Au, while an anelastic strain as large as the elastic strain is observed in the quasi-static test. The hardness and the tensile yield stress are about three time larger than those of the polycrystalline Au. Beyond a certain applied stress, however, the steady-state creep rate showed a steep increase. These characteristic mechanical properties are owing to the grain boundary regions with the much increased volume fraction and provide good workability of n-Au at elevated stresses. It is noted that n-Au is chemically stable and a potential candidate for a structured material of micromachines.

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High-density nanocrystalline (n-) copper with the density more than 96 % of bulk copper is prepared by a gas-deposition method. The hardness of n-copper is more than four times higher than those of the polycrystalline copper. Beyond a certain applied stress, the steady-state creep rate showed a steep increase by a few orders. These characteristic mechanical properties are very similar to those observed for the almost fully dense n-gold. We surmise that coexistence of the high strength and the large plastic deformation at higher stresses is the common feature for fcc n-metals owing to the grain boundary regions with the much increased volume fraction. Since copper can easy be removed by chemical etching, it is a promising candidate for the housing material of micromachines with fine and complex shapes.

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Amorphous metallic alloys constitute a promising new group of materials for micromachining. Their most significant advantage over silicon is that film deposition may take place at so low temperatures that polymeric sacrificial layers tolerate the process. This paper describes characterization of molybdenum-silicon-nitrogen alloys, representing the so-called "mictamict" group, by keeping the focus on properties relevant to microelectromechanical applications. Structural, mechanical, electrical, optical, and thermal properties are reported.

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In this work, we compare experimental results of mechanical testing, i.e. nanoindentation and microbeam deflection, on metal thin films on substrates. For these techniques, however, the required sample geometry, loading and straining conditions are quite different, and as a result, comparisons between the different techniques are difficult. It will be shown that a detailed computational analysis is required to identify material parameters such as yield strength and hardening modulus for the thin film materials. In particular, the use of neural networks to facilitate the analysis of plastic behavior is discussed. For both types of experiments, the general trend has been confirmed that the yield strength of thin metal films increases with decreasing film thickness. However, a detailed comparison of the deformation behavior shows significant differences between the different testing techniques.

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Micromachined films are proposed as mechanical clips to clamp optic fibres and other electrical components in optical packages. This paper reports mechanical test structures used to evaluate the properties of new materials for these MEMS and MST applications. A micromechanical beam 100μm wide and 400μm long is scanned with a stylus profilometer which deflects the beam, and the mechanical properties are deduced from the deflection characteristics. For example, prototype structures in 5μm thick silicon carbide film on a silicon substrate are produced by (a) laser cutting a track in the SiC film, (b) undercutting the SiC by anisotropic silicon etching using KOH in water, and (c) trimming if necessary with the focused laser system or with a focused ion beam. This approach has the advantages of fast design turn around and proof of concept, and it is practical to apply it to a wide range of materials. From the stylus profilometer data the Youngs modulus for chemical vapour deposited silicon carbide is 360 +/-50 GPa indicating that it is a promising material for packaging applications.

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SU-8 is a photoplastic polymer with a wide range of applications in microtechnology. Cantilevers designed for a commercial Atomic Force Microscope (AFM) were fabricated in SU-8. The mechanical properties of these cantilevers were investigated using two microscale mechanical testing techniques: contact surface profilometer deflection, known as MAT-Test, and static load deflection using a specially designed test machine, the MFT2000. The Young's modulus values from the microscale test methods are approximately 2-3 GPa. These results are compared with results from macroscale tests of 4-5 GPa. The test methods and the results are discussed.

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Dynamics of micro fluidic systems (MFS) is dominated by a fully coupled fluid-structure system. Hence, a subtle non-Newtonian property of a operation fluid often affects the system erformance. For measurements of such micro fluid properties, a squeeze flow rheometry is suitable, because a flow scale and a flow field which a test fluid undergoes are similar to those of the micro fluidic systems. Al-though the squeeze flow rheometry has a outstanding potential, it also has some intrinsic problems which come from the principle of measurements as well as the incompleteness of the instrument. In this paper, we propose a novel data manipulation method for a squeeze flow rheometry, which compensates those defects of the squeeze flow rheometer, and applying it to a instrument, demonstrate measurements of subtle non-Newtonian behavior: shear thinning and Thixotropy of dilute suspensions of monodisperse acrylic particles. In these measurements, a small Thixotropic viscosity change was detected in startup transition related to the reversible order-disorder transition of a colloidal structure. This measurement method can give indispensable information and means for investigation of non-Newtonian fluid dynamics and for developments of the MFS devices.

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Reliability issues such as crack propagation and lifetime are more and more crucial in commercial microelectromechanical systems (MEMS). Because conventional assessment methods have significant limitations in MEMS applications due to their very small scale, more advanced methods are required. This study focuses on a new methodology based on an analytical and statistical analysis of time-dependent degradation behavior of resonating structures. To predict reliability from the degradation behavior, we introduced a new concept, degradation rate. A single silicon tether-type resonating structure with a small sharp notch, fabricated by micromachining, was operated electrostatically at resonance mode and the decrease in resonant frequency with operation cycles was measured. We identified the degradation/failure mode and mechanism by analyzing the fracture surface. To investigate the effect of a notch as a local defect on failure, we deduced a relation between the stiffness of a notched beam and the resonant frequency of the structure and used it to quantify the effect of notch depth ratio and crack growth near the notch tip on stiffness degradation and ultimate time to failure. Finally, this degradation rate concept was used in a statistical analysis of the measured resonant frequency to evaluate the reliability function and hazard rate and predict the failure time of the structure. These predictions were compared with experiments to verify the validity of the proposed methodology.

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Adhesion strength of dissimilar materials at their interfaces determines mechanical reliability of micro- and nano-scale devices. Various methods have been proposed and utilized to measure adhesion strength. However, they are mostly based on macroscopic application of delamination stresses at interfaces. On the other hand, a nano-scratch technique has a potential to measure adhesion strength in a much smaller scale. This paper presents some examples of the experimental results obtained by nano-scratch test. An excellent correlation was found between the measured adhesion strength and themicrostructure observed by transmission electron microscopy. Finite element calculation of stress distribution during nano-scratch test indicated that a large tensile stress is concentrated at the interface ahead of the indenter tip. The stress concentration was limited in a small region of approximately 50nm on the interface plane. The results suggest that the nano-scratch test is capable of measuring adhesion strength in a 50-nm scale.

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A system of nanoindentation combined with atomic force microscopy was applied to a multi-phase material for evaluating its mechanical property. A tempered martensitic steel (SCM440) with a tensile strength of 1600MPa was tested as an example of multi-phase materials, and three types of tungsten single crystals , with respective (100), (110) and (111) surface, were also tested as reference. In the tempered martensitic steel, the load-displacement behavior depends on measured positions at the specimen surface and/or sizes of deformation zone. This behavior represents inhomogeneity of the multi-phase microstructure where each component has a different mechanical property and strength. When the contact depth reaches 60nm depth, the standard deviation of nanohardness becomes a constant value. Therefore, 60nm could be the critical contact depth for disappearance of inhomogeneity effect on the deformation behavior. The constitution of the standard deviation of hardness was discussed in some detail.

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Fracture and fatigue tests have been performed on micro-sized specimens for MEMS/MST applications. Cantilever beam type specimens (10 x 12 x 50μm^3) with notches were prepared from a Ni-P amorphous thin film by focused ion beam machining. Fatigue crack growth and fracture toughness tests were carried out in air at room temperature using a mechanical testing machine for micro-sized specimens. Fracture tests were performed for the specimens with fatigue pre-cracks ahead of the notches. Fatigue crack growth resistance curves were obtained from the measurement of striation spacing on the fatigue surface and closure effects were observed even for micro-sized specimens. Once fatigue crack growth occurs, the specimens were failed within one thousand cycles. This indicates that the fatigue life of micro-sized specimens is mainly dominated by a crack initiation. This also suggests that even micro-sized surface flaw may be an initiation site of fatigue crack and this will shorten the fatigue life of micro-sized specimens. As the results of fracture toughness tests, plane strain fracture toughness, K_<IC>, values were not obtained since the criteria of plane strain were not satisfied for this specimen size. As the plane strain requirements are determined by stress intensity, K, and yield stress of the material, it is rather difficult for micro-sized specimens to satisfy these requirements. Plane stress and plane strain dominated regions were clearly observed on the fracture surfaces and their sizes were consistent with those estimated by fracture mechanics calculations. This indicates that fracture mechanics is still valid for such micro-sized specimens. It is required to consider the results obtained in this investigation when designing actual MEMS/MST devices.

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The micro-electro-mechanical systems (MEMS) market requires the development and increased understanding of new micro-scale materials in order to continue to push its capabilities into new markets. Many of the applications of MEMS devices require the material to provide a high yield stress, superior creep strength and increased Young's modulus. These properties should be provided by material with a low density and the ability to be produced in a manner consistent with complicated, small scale components. For MEMS applications, requiring the retention of properties at temperatures in excess of 400℃, the application of compositions based upon the high temperature intermetallic γ-TiAl phase is being considered. A high strength alloy of this type, which has received significant attention in bulk form, is the composition Ti-46Al-5Nb-1W (at %). In this case this material is in the near fully lamellar form, having being produced with a colony size of 75μm. In this work samples with a cross section of &ap; 100μm x 10mm and micro sized cantilever beam samples, measuring &ap; 18μm x 6μm, were used to provide information upon the effect of thickness reductions upon the fracture toughness and fatigue properties of this alloy. This was completed using a specially developed testing machine which utilises a 250mN load cell to provide accurate loading through a diamond tip to such small cantilever beams. The paper includes both a comparison between these micro sized values and those of the thin film material as well as information upon the orientation dependence of these properties resulting from trans- and inter-lamellar failure modes.

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This paper deals with characterization of micro electro mechanical systems (MEMS) under cyclic loading; such characterization is essential to confirm the reliability of MEMS in practical applications. Examples include torsion beams supporting a micro mirror of an optical matrix switch, a cantilever with a vertical micro mirror of an optical bypass switch, and thermo-elastically deformed 3-D structures. Those devices are made of poly or single-crystal silicon. Typical life time of these devices exceeded a few tens of million cycles.

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MEMS(Micro ElectroMechanical Systems) and NEMS(Nano ElectroMechanical Systems) have been developed based on a silicon bulk-micromachining. Electrostatically levitated ring rotor gyroscope, thermal RF relay for LSI tester, on-chip AlN thin film resonator, components for multi-column electron beam lithography system and multiprobe data storage system and carbon nano-tube structures are described.

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There is an increasing necessity to record the deformation characteristics of microelements often consisting of freestanding foils and wires. The data required are either mechanical or thermal such as Young`s moduli, stress-strain values, fatigue- and thermal strain data, but the nominal strength of a structure changes by scaling its size. Due to this size effect, material data cannot be taken from macrospecimens, thus special testing procedures were introduced. Laseroptical sensors based on the speckle correlation method were applied to determine non-contacting strain values with high strain resolution. For the mechanical properties tensile tests were used for the freestanding foils and wires. For thermal strain measurements a laser speckle based dilatometer was designed. A short outline of applicability of the testing equipment is given. The following materials data are presented and discussed: Young`s modulus, mechanical and thermo-mechanical and thermal strain data of various Cu foils and wires with varying grain sizes, thickness and defined texture. A thickness effect was detected and is interpreted in terms of a "thickness to grain size ratio" approach.

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Finite element models of polycrystalline thin films were constructed based on the Monte Carlo method. The models consisted of columnar aggregates of cubic crystals with fiber texture whose axis was <001> direction perpendicular to the film surface. In the Monte Carlo method, the nucleus of a crystal was distributed at positions generated by the random number, and the crystal boundary was formed from the coordinates of the nucleus of crystals by using Voronoi tessellation. The number of grains in a sample volume was varied 10 to 1000, and fifty models with different orientations were produced for each case. A constant uniaxial displacement was applied to the models to examine the scatter of elastic properties of thin films under the conditions of plane strain and plane stress. The scatter and mean values of Young's modulus and Poisson's ratio were obtained as functions of the number of the grains within a sample volume. A method is proposed to determine the number of grains for thin films to have macroscopic properties for various thin films with different degrees of elastic anisotropy.

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Electrical resistivities of PdCuSi thin film metallic glasses (TFMGs) are investigated as a function of annealing conditions in an attempt to control crystallization of the PdCuSi TFMG in order to reduce electrical resistivity without inducing embrittlement. Glass transition temperature T_g, crystallization temperature T x and electrical resistivity of the as-sputtered Pd_<76>Cu_6Si_<18> TFMG are 638K, 663K and 64μΩcm. Resistivity of Pd _<76>Cu_6Si_<18> TFMG is found to decrease as crystallization proceeds. Although the resistivity of Pd_<76>Cu_6Si_<18> TFMG annealed at 633K (= T_g - 5K) for 60s does not decrease, because the material remains amorphous, the resistivity of Pd_<76>Cu_6Si_<18> TFMG annealed at 633K for 600 s does decrease by a few K, even though the specimen is still amorphous. Stress relaxation of Pd_<76>Cu_6Si_<18> TFMG is thus thought to occur by glass transitions. When annealed at 633 K for over 1200s, Pd_<76>Cu_6Si_<18> TFMG becomes partially crystallized, and electrical resisitivity decreases with increasing annealing time. Pd_<76>Cu_6Si_<18> TFMG annealed at 633K for 2700s becomes completely crystallized, giving an electrical resisitivity of about 30μΩcm. Annealing Pd_<76>Cu_6Si_<18> TFMG at 643K (= T_g + 5K) for 600s also results in complete crystallization. During crystallization of Pd_<76>Cu_6Si_<18> TFMG, γ-(Pd-Cu) and Pd solid solution crystallize first out of the amorphous phase. At this point, Pd_<76>Cu_6Si_<18> TFMG exhibits a sufficiently high strength, with electrical resistance reduced to about 50μΩcm. After further annealing, Pd-silicides, Pd_4Si and Pd_3Si, are formed and Pd_<76>Cu_6Si_<18> TFMG is crystallized completely. Although this gives an electrical resistivity of about 30μΩcm, the specimens become very brittle.

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PAN gel has been known for the fast responsive and highly deformable properties by the acid-base bathing solution exchange, yet its durability in the basic solution is not high enough. Effective thermal treatment was given to the ingredient of PAN gel, Silpalon fibers, in the course of the preparation of PAN gel. We performed quantitative evaluations on the performances of this PAN gel - length change behavior, force generation behavior, and durability-. It was found that this PAN gel has a relatively superior durability than another PAN gel prepared through the non-effective thermal treatment. This PAN gel could not acquire the performance of large generated force nor large length change, yet still they are large enough for the sake of using it as an actuator material.

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Plain fatigue strength of cold-rolled and forged Ti-29Nb-13Ta-4.6Zr(TNTZ) aged after solution treatment is much greater than that of TNTZ conducted with solution treatmet in both low cycle fatigue and high cycle fatigue life regions. The plain fatigue strength of TNTZ is not degraded in Ringer's solution. Fretting fatigue strength of forged TNTZ and Ti-15Mo-5Zr-3Al conducted with various heat treatments decreases dramatically as compared with their plain fatigue strength in both low cycle fatigue and high cycle fatigue life regions. In this case, the decreasing ratio of fretting fatigue life increases with increasing the small crack propagation area where both the tangential force and frictional force exist at the contact plane of pad. In fretting fatigue in air, the ratio of fretted damage (P_f/F_f), where P_f and F_f stand for plain fatigue limit and fretting fatigue limit, respectively, increases with increasing elastic modulus. In fretting fatigue in Ringer's solution, the passive film on specimen surface is broken by fretting action in TNTZ, which has excellent corrosion resistance, and, as a result, corrosion pits that lead to decreasing fretting fatigue strength especially in high cycle fatigue life region, are formed on its surface.

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Ti with 30 mass% Nb + 10 mass% Ta + 5 mass% Zr, that is, Ti-30Nb-10Ta-5Zr, which is simplified chemical composition of Ti-29Nb-13Ta-4.6Zr, was decided as basic composition to investigate the effect of alloying element Nb on mechanical properties of Ti-Nb-Ta-Zr system alloys in this study. Ti-Nb-10Ta-5Zr alloys with different Nb contents were fabricated by blended elemental powder metallurgy method. The elastic modulus and tensile properties of the designed alloys were investigated. While, the microstructures of these alloys were observed by using an optical microscope and a transmission electro microscope. The alloy with 0 mass% Nb shows a microstructure consisting of single α phase. Precipitation of ω phase and α'' phase are observed in the alloys containing of 10 mass% and 15 mass% Nb. The alloys containing of over 20 mass% Nb shows ω phase precipitated in β phase. The alloys containing of over 30 mass% Nb show single β phase. Variation of microstructure, elastic modulus, elongation, reduction of area, 0.2% proof stress and tensile strength become smaller in the alloys containing of over 35 mass% Nb. The alloy containing of 30 mass% Nb shows the lowest elastic modulus. A deformation mechanism that is different from the general slip deformation of titanium alloy appears in the alloy containing of Nb between 20 mass% and 30 mass%.

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The dental castings contain casting defects such as micro shrinkages, pores, surface roughness, etc. Cyclic stress, that is, fatigue stress due to the mastification is applied to the dental prosthesis in the practical use. Therefore, the effects of the casting defects such as micro shrinkage and pore on the fatigue properties of the cast Ag-Pd-Cu-Au-Zn type alloy were investigated in the comparison with the fatigue properties of the drawn Ag-Pd-Cu-Au-Zn alloy in this study. Moreover, in this study, cast Ag-Pd-Cu-Au-Zn type alloys that were manufactured using a dental casting machine were conducted with two kinds of heat treatments. The fatigue strength of the cast alloy is considerably smaller than that of the drawn alloy. The size of the micro shrinkage affects the fatigue strength of this cast alloy strongly. The fatigue crack of the cast alloy initiates preferentially at the micro shrinkage near the specimen surface. The fatigue strength of solutionized cast alloy is greater than that of as-cast alloy. However, the fatigue strength of the aged cast alloy is nearly the same as that of as-cast alloy. The fatigue strength of this cast alloy can be raised by controlling its microstructure through heat treatments.

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