Practical engineering materials are generally complicated and computer applications to materials science are wide and need some idea to calculate. Some of the applications are mentioned. As examples of calculations, atomic configurations and stability of vacancy clusters, atomic configurations of dislocation cores are shown. Using molecular dynamics, rapid quenching of liquid, tensile deformation of amorphous and crystalline iron, shear plastic deformation of copper small crystals, lattice vibrations are described.

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All the first order phase transformations proceed through the nucleation and growth process. The martensitic transformation is characterized by the synchronized motion of a group of atoms. The problem of the nucleation of the martensite is to find a nucleation mechanism compatible with the synchronized and finite displacement of a group of atoms, which consists of the synchronized dislocation slips of neighboring slip planes. The synchronized dislocation slip is discussed in terms of two models: the modified version of the nucleation model and the one-dimensional large amplitude lattice vibration model. The negative surface energy for the coherent interface is introduced to the nucleation and growth model in order to take into account that the elementary microscopic process in the martensitic transformation is the synchronized motion of atoms in a slip plane. The major theories proposed for the martensitic transformation, the classical nucleation theory, the local soft mode theory and the dislocation theory, are briefly discussed from the viewpoint presented above.

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The effect of etching temperature on the dissolution rates at edge dislocation and dislocation-free sites of the (111) surface of copper single crystals was studied. The etching was carried out at temperatures 270 to 285 K for 5 to 25 s with Young’s etchant containing (NH₄)₂S₂O₈ 1 kmol·m⁻³, NH₄OH 6 kmol·m⁻³ and NH₄Br 0.3 kmol·m⁻³. From the measured data on the width and depth of dislocation etch pits and the dissolved thickness of the (111) matrix surface as a function of etching time, the lateral dissolution rate across the surface at dislocation v_h, the longitudinal one along dislocation v_d, and the dissolution rate normal to the surface at dislocation-free sites v_s, were determined. It was found that the dissolution rates were in the order of v_h>v_d>v_s at any temperature and that they increased as the etching temperature increased. These results were qualitatively discussed on the basis of the kinetic theory of two-dimensional nucleation and step motion for crystal dissolution, and some kinetic quantities relating to the formation of two-dimensional nucleus and the step motion were evaluated.

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Three kinds of Cu-13.7Al-4.0Ni (mass%) alloy single crystals have been prepared by rapid (R.Q.) and normal (N.Q.) quenching from 1273 K and by aging at 523 K after the N.Q. treatment (A.), the martensites formed in them being the β′₁, a mixture of the β′₁ and γ′₁ and the γ′₁, respectively. They have then been subjected to training cycling, which consists of cooling below M_f, bending of 2.6% strain in maximum and heating up above A_f, up to 1000 cycles. As a result, the two-way shape memory effect (TWSME) was found to appear in Sps. R.Q. and N.Q., but not in Sp. A., indicating that the appearance of TWSME depended on the crystal structures of martensites in specimens. The martensites in Sp. N.Q. on quenching changed to only the β′₁ on the way of the training cycling. Fairly reproducible microstructures of the β′₁ was observed in Sp. R.Q. even in the non-trained condition, and the reproducibility increased with the number of training cycles. Meanwhile, no reproducibility of microstructures of the γ′₁ was observed in Sp. A. at all both in the non-trained and trained conditions. Thus, the β′₁ was found to be the martensite phase responsible for the appearance of TWSME. This difference in the appearance of TWSME between the β′₁ and γ′₁ was elucidated in terms of some difference in the number of dislocations introduced during the training cycling and in the nucleation and growth characteristics of the martensites nucleated at the dislocations.

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The influence of low cycle fatigue (LCF) deformation on the microstructure of a CrMoV rotor steel service exposed at 510°C for 23 years has been investigated by conducting transmission electron microscopy studies on thin foils made from shoulder and gage sections of the fatigue specimens tested at 538°C using different strain ranges with or without 1 h hold period. The LCF deformation has led to the spheroidisation of coarse cementite present along the grain boundaries as well as within the bainitic ferrite, a slight coarsening of vanadium-rich MC type carbide and profuse precipitation of molybdenum rich M₂C type carbide as fine platelets. Increasing strain range or superimposing hold period at the peak tensile load during LCF testing has accelerated these changes.

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Pulsed MIG welding of Al–Zn–Mg alloy has been carried out by using extruded sections of base material and Al–Mg (5183) filler wire. During welding the pulse parameters such as the mean current and pulse frequency are varied and their effect on the chemical composition, susceptibility to precipitation, morphology and hardness of weld bead have been studied. For a comparative study weldments are also prepared by using conventional continuous current MIG welding process, where the welding currents equivalent to that of mean currents of pulsed process are used. The characteristics of weld bead concerning the aspects mentioned above are found to be affected by the mean current and pulse frequency. The hardness of weld bead has been found to be governed by the precipitation as well as the morphology of weld bead, where the presence of a higher amount of zinc in it results in enhancement in the precipitate ((Al, Zn)₄₉Mg₃₂) content and the coaxial growth of dendrite favours the increase in hardness of weld bead.

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Oxidation behavior of a TiAl coupon was studied in a temperature range 1100 to 1400 K in a flow of purified oxygen at atmospheric pressure using thermogravimetry and standard metallographic techniques. The oxidation kinetics initially follows approximately a linear rate law. The oxidation rate decreases gradually as the oxidation proceeds. However, they never follow the parabolic rate law. This is attributable to the crack formation near the scale/substrate interface. The oxide scale has two layers: an outer layer consisting mainly of rutile and an inner porous layer consisting of a mixture of rutile and α-alumina. The preferential growth of rutile is responsible for the initial kinetics. Large voids are developed near the interface between the outer and inner oxide layers. Thin alumina platelets grow almost normal to the substrate surface as an internal oxide near the scale/substrate interface. The lamellar structure thus developed is maintained in the scale near the interface.

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The ammoniacal leaching is apparently considered an attractive approach to process polymetallic sea nodules wherein copper, nickel and cobalt are solubilised forming the ammine complexes. To separate these metals, LIX 84, an oxime extractant, was tried from the synthetic solutions. The loading capacity of this solvent for individual metal and ammonia extraction was determined and compared with that of LIX 64N. Preferential extraction of copper over nickel from a mixed aqueous solution was observed. The kinetic studies for the extraction of metals were undertaken to arrive at the retention time appropriate for this operation. Before metal stripping, the mode of ammonia scrubbing from the organic was worked out using acid or a combination of ammonia-dilute acid as the reagents. The coextraction of nickel and copper and their selective stripping were considered to explore the possibility of separating Cu, Ni and Co from ammonia-ammonium carbonate medium. The separation of these metals from the ammoniacal leach liquor of sea nodules was also attempted.

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The surface tension of the liquid binary alloys Ni–Cu, Ni–Sn, Fe–Cu, Fe–Sn, and Fe–Cr have been measured by the levitated droplet method. The results for Ni–Cu have been compared to duplicate measurements using the sessile drop method. It was found that the surface tensions of liquid Ni and Fe decrease sharply with increasing Sn and Cu content, while there is little effect of Cr on the surface tension of liquid Fe. The results suggest that levitation technique which is a dynamic rather than a static method of surface tension measurement yields equilibrium and static values of surface tension of binary alloys.

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E.M.F. of galvanic cells with the solid electrolyte (ZrO₂(+Y₂O₃)) was measured to determine the activity of zinc in the whole composition range for ZnTe–CdTe solid solutions coexisting with tellurium-rich and poor-ternary liquid phases in the temperature ranges 831–952 K and 802–896 K, respectively. The cells used were as follows:
(−) Kanthal |Re| (ZnTe)_x(CdTe)_1−x, Te or Zn, ZnO |O²⁻| air, Pt (+). Activity of zinc in the Te-rich region increases monotonously from 0 to the order of 10⁻⁶ at 923 K with the increasing of ZnTe. On the contrary the activity of zinc at 873 K in the Te-poor region hardly increases with the ZnTe composition up to 0.7 mole fraction of ZnTe, but increases keenly in the higher range of ZnTe.
The phase relation at 873 K in the Zn–Te–Cd ternary system was determined for the quenched specimen.
The activity of ZnTe was also derived from the emf measurements in this study for the Te-rich solid solutions.

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The static softening processes taking place after dynamic recovery (DRV) and dynamic recrystallization (DRX) were studied by means of interrupted tensile tests for a 0.4%C-1.5%Mn steel at a temperature-compensated strain rate Z. The softening curves associated with a DRV matrix (ε=0.1) consist of two stages followed by complete softening, in which (i) classical recovery and (ii) classical recrystallization take place in sequence. In contrast, the softening curves in a full DRX structure (ε=0.26) consist of three distinct stages with the respective inflection plateaus, followed by incomplete softening. The controlling mechanisms operating in each stage are mainly (i) metadynamic recrystallization, (ii) metadynamic recovery and classical recrystallization, and (iii) grain growth. Both the activation energy and the Avrami exponent in stage 2 for a DRX matrix is clearly smaller than those for static recrystallization. It is concluded that all stages of softening after DRX can be strongly affected by the existence of growing DRX grains, which have no potential for classical nucleation, and also by the role of metadynamic recovery taking place within them.

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The wear resistance for hypereutectic Al–Si alloys and Al–Si, 6061, 4032 alloys reinforced with Al₂O₃ fibers, SiC particulates, SiC whiskers, C fibers and Pb particulates has been investigated. The wear loss for hypereutectic Al–Si alloys is observed to be inversely proportional to the size and directly proportional to the spacing of Si particles and the counter material surface roughness. The effect of SiC whisker on wear resistance for Al–Si alloys is found to be a superimposing of the direct contribution of SiC whisker on the secondary effect on pinning the slip of Si particles. The composites reinforced with a hybrid of SiC whisker, SiC particulate and C fiber exhibit excellent wear resistance. SiC whisker is found to be a barrier against slip of relatively large reinforcements.

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The microstructural characteristics of Al–Si alloys (BSS: LM6, LM13, LM30) with 3.0 mass% dispersion of graphite particles (size: 63–120 μm) are studied, using scanning electron microscope interfaced with wavelength dispersive X-ray spectrometer, giving special emphasis on the morphology of alloy phases and distribution of graphite particles. Metallographic examination revealed that in hypoeutectic Al–Si alloy, the first phase to solidify, i.e., primary aluminium avoids graphite particles and nucleates preferentially between the graphite particles. Graphite particles are usually pushed by the primary aluminium dendrites into the last freezing eutectic phase. In hypereutectic Al–Si alloy (BSS: LM30), coarse primary silicon is found to nucleate preferentially on the surface of the dispersed graphite particles. The presence of aluminium halos are observed in LM30 alloy; in the case of alloys containing 3.0 mass% graphite particle dispersion, halo formation is suppressed. The observed effects appear due to heterogeneous nucleation and alteration in heat, fluid and mass transport due to dispersed graphite particles on a microscopic level. The effect of graphite particles on the microstructure of rapidly solidified Al–Si alloy is also discussed with reference to growth of silicon phase. Microstructures of rapidly solidified composites showed that near the graphite particles eutectic silicon grew as plate-shaped, whereas, away from the graphite particles it was near-spherical in shape. This alteration of growth morphology of eutectic silicon was attributed to the thermal barrier offered by the suspended graphite particles during solidification.

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Thin multilayered films of [Pt(1.2 nm)/Mn(1.2 nm)/Sb(2.6 nm)] and [Pt(1.0 nm)/Mn(2.0 nm)/Sb(2.0 nm)] were prepared on glass substrates by an ion-beam sputtering method, and the formation of the C1_b–PtMnSb phase in the as-deposited films was investigated by means of X-ray diffraction and transmission electron microscopy. The multilayered samples produced at room temperature consisted of a layered structure of amorphous or nano-crystalline phases. In contrast to this, as the substrate temperature increased up to about 473 K, inter-layer mixing among the constituent multilayers was found to occur and the PtMnSb phase was evolved preferentially. In addition, the platinum layer inserted as a buffer between the glass substrate and films showed a significant effect on the growth of the PtMnSb phase with preferred orientation.

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