To establish the measuring technique of neutron diffraction for the internal residual stress distribution in a structural component, a neutron diffraction apparatus was designed and manufactured in Japan Research Reactor No.3 (JRR-3). At the first step of measurement, basic characteristics of the diffractometer was evaluated. The incident neutron beam flux was 104 n/cm2/s and the Full Width at Half Maximum (FWHM) of diffracted neutron profile was about 0.3 degree. This indicates that the manufactured neutron diffractometer is capable for the residual stress measurement. As the first application of the neutron diffraction measurement, the residual stress distribution in plastically bent carbon steel plate was measured. A typical compressive-tensile-compressive-tensile residual stress pattern in the tangential direction in the bent plate was confirmed. The maximum stress near the surface was about 180 MPa. This means that the technique for residual stress measurement by neutron diffraction method can be established in Japan.
This paper reviews a previously reported paper published in the Journal of the Society of Materials Science, Japan (Vol. 68, No.10, pp.733-738(2019)). The original paper describes the specific growth mechanism of metastable oxides using the mist CVD technique, and is of great usefulness for growing them with this technique, which requires relatively low growth temperatures and normal pressures. Metastable oxides have been gaining increasing attention for their unique and excellent physical characteristics. The Mist CVD technique is a key to synthesizing a wide variety of metastable materials efficiently.
In this paper, we describe the conformational stability due to the local structural change of tetraethylammonium ion (abbreviated as Et4N+) in water and alcohols. Our results indicated that the conformational stability of Et4N+ has a close relation to the solvation of aqueous tetraalkylammonium salt (R4NX) solutions. Furthermore, we discussed the relationship between the thermodynamic properties and microscopic information. We showed that the hydrophobic interactions and hydration are affected by the enthalpy and entropy differences of the Et4N+ conformers in aqueous Et4NX solutions, where the thermodynamic parameters of the conformers may be useful for explaining the changes.
Zr-Cu shape memory alloys have considerable promise as a high temperature shape memory alloy. Shape memory behavior of the alloy is induced by the effect of martensitic and reverse martensitic transformation behavior of the intermetallic compound ZrCu. Previous reports suggest that additional elements such as Al, Cr, Co and Ni, etc. are effective to control martensitic transformation temperature of Zr-Cu system shape memory alloys. The objective of the present study is to investigate the compositional dependence of crystalline structure, martensitic transformation temperature and mechanical property of Zr-Cu system shape memory alloy. Near equi-atomic Zr-Cu binary and equi-atomic Zr-Cu system ternary alloys were fabricated by arc melting method with different alloy compositions. Especially, in the present study, Al was used as the third additional elements. The crystalline structures, martensitic transformation temperatures and hardness of fabricated alloys were investigated by means of X-ray diffraction(XRD), differential scanning calorimetry(DSC) and Vickers hardness test. As the results, it was found that the intermetallic compound ZrCu martensite phase was formed in both Zr-Cu binary and Zr-Cu-Al ternary alloys. Furthermore, it was found that martensitic transformation temperatures (Ms, Mf, As and Af) of Zr-Cu-Al alloys can be controlled by the concentration of added Al. In addition, Vickers hardness test results suggest that the hardness of ZrCu (parent phase) is lower than that of ZrCu (martensite phase).
Uniaxial tensile deformation of single-crystalline and polycrystalline α-Ti models was numerically simulated with strain rates ranging from 10-4 to 10-1 [/s] using a crystal plasticity finite element method, and we investigated the relationship between the activities of the basal and prismatic <a> slip systems and the critical resolved shear stresses (CRSSs) depending on the strain rates. The simulation of single-crystalline model showed that CRSS of prismatic <a> slip system was easier to increase than that of basal slip system although CRSS of both slip systems increased with strain rates. The nature of strain rate dependency affected the deformation mechanism of polycrystalline model: the simulation of polycrystalline model showed that the activity of basal slip system increased locally with strain rates, instead of reducing that of prismatic <a> slip system. However, the local activation of basal slip system was inhibited when 1st pyramidal <a> slip system was activated. These results indicate that the local activation of basal slip system can occur by strain redistribution between preferred regions for basal and prismatic <a> slips with strain rates while activation of another slip system can inhibit that of the basal slip system.
Composite material immobilized silver nanoparticles (NPs) on the surface of cellulose nanofibers (CNF) was prepared using a high-pressure wet-type jet mill. A mixture containing both aqueous silver nitrate solution and CNF suspension were prepared as raw starting materials. The mixture was pulverized with a high-pressure wet-type jet mill at a pressure of 100 MPa or 200 MPa. An X-ray diffraction pattern of the obtained sample revealed not only cellulose type I crystallites, but also silver metal crystallites. According to observation by field-emission scanning electron microscopy, it was found that many silver NPs were immobilized on the surface of CNF. Note that almost the silver NPs were well dispersed on the surface of CNF. It was cleared that the silver NPs had spherical in shape with an average particle size of about 3 nm by the transmission electron microscope observation. The average size of silver NPs was slightly increased with increasing the number of jet milling, however, the change in discharge pressure of the high-pressure wet-type jet milling did not affect the size of silver NPs. The silver content in the composite materials increased with increasing both the number of jet milling and the discharge pressure. The silver particles were deposited with using the thermal energy caused by the jet milling, and then their grain growth was inhibited since the suspension was cooled immediately through the cooling tube. Therefore, it was assumed that silver NPs with a narrow size distribution could be immobilized on the surface of CNF.
An aluminosilicate solid is an inorganic material that has the property of immobilizing heavy metals or radionuclides in the matrix. In this study, aluminosilicates with a Si / Al molar ratio of 0.5 was synthesized from a chemical reagent in order to produce aluminosilicate solids with a low Si / Al molar ratio, which were expected to improve the immobilization of heavy metals and radionuclides contained in the matrix. The synthesized Si-Al gel with a Si / Al molar ratio of 0.5 had little impurity content and was in an amorphous phase. In addition, the compressive strength of the aluminosilicate solid produced by the synthesized Si-Al gel showed a 5 MPa or more, confirming that it can be used as a raw material for aluminosilicate solids. The aluminosilicate solid with a Si/Al molar ratio of 1.25 had a dense surface structure from the result of BSE images and had the highest compressive strength among all samples.
In our previous study, we proposed a new technique to analyze the asymptotic solution of the singular stress field around a three-dimensional interfacial corners under mechanical stress. We analyzed the scalar parameters of the asymptotic solutions using the H-integral, which is a conservation integral, in conjunction with the finite element analysis. In this study, we extended the previous study to the three-dimensional interfacial corners under thermal stress. Thermal stress is the main cause of the fracture from an interfacial corner between dissimilar materials. We also normalized the scalar parameters that is compatible with the scalar parameters obtained by two-dimensional H-integral using the Stroh formalism. We demonstrate that the obtained eigen vectors and scalar parameters are correspond with that obtained by the two-dimensional method. We have also shown an example of perfect three-dimensional corners under thermal stress. Obtained asymptotic solution reasonably approximated the stress field around the corner.