Papers by Author: Hiroyasu Kanetaka

Paper TitlePage

Authors: Motoki Okuno, Tomonari Inamura, Hiroyasu Kanetaka, Hideki Hosoda
Abstract: Deformation behavior and texture development of NiMnGa ferromagnetic shape memory alloy (FSMA) particles embedded polymer composites were investigated by compression tests and X-ray diffraction pole-figure analysis (XRD-PF). Both the NiMnGa/silicone and NiMnGa/epoxy composites exhibited a characteristic three-stage deformation which is often seen in shape memory alloys due to martensite variant reorientation. XRD-PF revealed that (004) texture was developed in the compressed NiMnGa/silicone due to the retention of martensite variant reorientation. On the other hand, significant texture change was not recognized in the compressed NiMnGa/epoxy. Rearranged martensite variants was kept after unloading in silicone matrix having low Young's modulus, but reverse reorientation occurred in epoxy matrix with high Young's modulus. The rearrangement behavior of martensite variants is strongly affected by elastic properties of matrix.
Authors: Hideki Hosoda, Makoto Taniguchi, Tomonari Inamura, Hiroyasu Kanetaka, Shuichi Miyazaki
Abstract: Effects of single- and multi-step aging on mechanical properties and shape memory properties of Ti-6Mo-8Al (mol%) biomedical shape memory alloy were studied using tensile tests at room temperature (RT). The solution-treated alloy at RT was two phase of bcc β and martensite α". Tensile tests revealed that the solution-treated alloy exhibited good shape memory effect. As for the single-step aging, (1) pseudoelastic shape recovery by unloading was observed after aging at 623K, (2) the alloy became brittle after aging at 773K due to ω embrittlement, and (3) strength was improved with small shape memory effect by aging at 1023K. On the other hand, after a multistep aging at 773K-1023K-1123K, the alloy was strengthened and showed perfect shape recovery. The improvement must be achieved by the formation of fine and uniform hcp α precipitates.
Authors: Yuichi Nakahira, Tomonari Inamura, Hiroyasu Kanetaka, Shuichi Miyazaki, Hideki Hosoda
Abstract: Effect of nitrogen (N) addition on mechanical properties of Ti-Cr-Sn alloy was investigated in this study. Ti-7mol%Cr-3mol%Sn was selected and less than 0.5wt% of N were systematically added. The alloys were characterized by optical microscopy, X-ray diffraction analysis and tensile tests at room temperature. The apparent phase was β (bcc) phase, whereas the presence of precipitates was confirmed in 0.5wt%N-added alloy only which did not exhibit sufficient cold workability. The grain size was not largely affected by N addition being less than 0.5wt%. Tensile tests revealed that less than 0.5wt%N addition improves the strength which is due to the solution hardening by interstitial N atoms.
Authors: Yui Watanabe, Motoki Okuno, Yoshinaka Shimizu, Hiroyasu Kanetaka, Tomonari Inamura, Hideki Hosoda
Abstract: Effect of elastic modulus of matrix on ferromagnetic motion of NiMnGa particles was investigated for NiMnGa particles embedded silicone matrix composites with or without containing polystyrene form particles (PFPs), which are regarded as pores. NiMnGa single crystal was fabricated by a floating zone method and a cube-shape particle was fabricated with the surface orientation parallel to [100], [010] and [001] directions at the parent phase state. The elastic modulus of matrix polymer was controlled by changing the number of PFPs. It was found that the elastic modulus of silicone was decreased with increasing the volume fraction of PFPs. The magnetic-field-induced martensite variant reorientation (MVR) was evaluated by the magnetization curves obtained using a vibration sample magnetometer, and the magnetic field required for the start of martensite variant reorientation was reduced by increasing the number of PFPs. The control of elastic modulus of matrix polymer is important and a dominant factor for the magnetic motion of NiMnGa/polymer composites.
Authors: Taku Aoki, Masaki Tahara, Kenji Goto, Yoko Yamabe-Mitarai, Hiroyasu Kanetaka, Tomonari Inamura, Hideki Hosoda
Abstract: The effects of Fe addition on martensitic transformation and mechanical properties of AuTi were investigated in this study. It was found that B2 parent phase is stabilized by the Fe addition and that AuTi can contain at least 20mol%Fe. The lattice deformation strain evaluated from θ-2θ X-ray diffraction analysis (XRD) is not significantly changed by the Fe addition. The decrease in Ms evaluated by differential scanning calorimetry (DSC) is-40K/mol%Fe. Tensile tests revealed that, with increasing Fe content, the yield stress decreases up to about 13mol%Fe, largely increases up to 15mol%Fe and then decreases gradually. By taking into account XRD and DSC results, these behaviors are judged to correspond to reorientation of martensite variants, stress induced martensitic transformation and slip deformation of parent phase, respectively. The values of dσSIMT/dCFe and dσSIMT/dT are evaluated to be-170MPa/mol%Fe and-4.3MPa/K, respectively. The elongation is degraded with increasing Fe content from 8% in AuTi (0mol%Fe, martensite phase) to 2% in AuTi-20mol%Fe (parent phase) depending on the apparent phase.
Authors: Yuri Shinohara, Takuya Ishigaki, Tomonari Inamura, Hiroyasu Kanetaka, Shuichi Miyazaki, Hideki Hosoda
Abstract: The phase constituents of the Ti-Cr-Au ternary and Ti-Cr-Au-Zr quaternary systems were investigated using X-ray diffraction analysis and optical microscopy. The composition ranges were 3~10mol%Cr and 0~8mol%Au for the ternary system, and 0~42mol%Zr were added to Ti-5mol%Cr-4mol%Au. It was found that the β phase was stabilized by the addition of Cr and Zr, and that A15-type Ti3Au was formed when the Au content was 6mol% or higher. Besides, C14 Laves phase similar to Zr33Ti40Au27 was recognized in Ti-5mol%Cr-4mol%Au-42mol%Zr.
Authors: Taywin Buasri, Hyun Bo Shim, Masaki Tahara, Tomonari Inamura, Kenji Goto, Hiroyasu Kanetaka, Yoko Yamabe-Mitarai, Hideki Hosoda
Abstract: Phase constitution and martensitic transformation behavior were investigated for a Au–51Ti–18Co alloy heat-treated at 1173 K to 1373 K for 3.6 ks. The Au–51Ti–18Co alloy was fabricated by Ar arc-melting technique and subsequently by hot-forging at 1423 K for 10.8 ks. X-ray diffraction analysis revealed that B2 parent phase, B19 martensite phase and AuTi3 simultaneously appeared regardless of the heat-treatment temperatures. By increasing the heat-treatment temperature, the volume fraction of AuTi3 was slightly reduced. Besides, the lattice transformation strain which was calculated from the precisely-determined lattice parameters was evaluated to be 7 % in the Au–51Ti–18Co alloy in all the heat-treated conditions. This value is comparable to that of NiTi practical alloys. From differential scanning calorimetry (DSC) analysis, reverse martensitic transformation temperature was slightly increased with the heat-treatment temperature. From the lattice transformation strain point of views, the Au–51Ti–18Co has a large potential for novel biomedical shape memory alloy.
Authors: Yasuhiro Kusano, Tomonari Inamura, Hiroyasu Kanetaka, Shuichi Miyazaki, Hideki Hosoda
Abstract: In order to produce new β (bcc) Ti alloys for medical applications, effects of Mn substitution for Cr on phase constitution and mechanical properties of Ti-Cr-Sn alloys were investigated. All the Ti-7mol%(Cr, Mn)-3mol%Sn alloys investigated by XRD analysis were identified as β (bcc) alloys, and athermal ω phase was also detected in Ti-7mol%Mn-3mol%Sn . The lattice parameter of β was slightly decreased by Mn substitution. Besides, the Mn substitution for Cr raised the hardness and the strength while reduced the ductility of the Ti-Cr-Sn alloys. The hardening by Mn substitution must be due to ω precipitation. The hardening is discussed from the viewpoint of electron atom ratio (e/a) in comparison with Ti-Cr binary alloys in the literature.
Authors: Tomonari Inamura, Hideki Hosoda, Hiroyasu Kanetaka, Hee Young Kim, Shuichi Miyazaki
Abstract: The self-accommodation microstructure of a -titanium shape memory alloy (SMA) was investigated by conventional transmission electron microscopy (CTEM) observation. There were two distinct minimum units for the self-accommodation microstructure. One was the V-shaped pair of two habit plane variants that were bounded by the {111}TypeI twin as reported in some previous studies. The other was the bundle of the two habit plane variants that were bounded by the <211>TypeII twin. The later one had not been recognized as the self-accommodation microstructure in -titanium SMAs.
Showing 1 to 9 of 9 Paper Titles