Since the maximum shape recovery temperature of the binary Ti-Ni alloys is limited to be around 400K, the increase in martensitic transformation temperature (Ms) of Ti-Ni should be done by alloying for the demand of high temperature applications. Although most of additional elements are known to decrease Ms of Ti-Ni, substitutional elements having large atomic size are expected to increase Ms. In this study, phase constitution, phase transformation temperature, lattice parameter of B2 phase and Vickers hardness were investigated for Ti-Ni alloys containing several platinum-group metals (PGM). The alloy systems investigated were the pseudobinary systems of TiNi-TiRh, TiNi-TiIr and TiNi-TiPt where the PGM atoms substitute for the Ni-sites of TiNi, The phase transformation and phase constitution were assessed by differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). It was found by XRD that TiNi can contain a large amount of the PGMs as Ti(Ni, Rh), Ti(Ni, Ir) and Ti(Ni, Pt). Lattice parameters monotonously increase with increasing amount of PGMs. With increasing Pt content, Ms slightly decreases when less than 10mol%Pt while continuously increases as the rate of 26K/mol%Pt when more than 10mol%Pt. On the other hand, Ms decreases and then disappears with increasing Rh or Ir content. Hardness ranges from HV180 to HV570 and the maximum values in the pseudobinary systems lie around 20-30mol%PGM, suggesting solid solution hardening caused by the substitution of PGMs.
|ジャーナル||Materials Research Society Symposium - Proceedings|
|出版ステータス||Published - 2003 11 10|
|イベント||Defect Properties and Related Phenomena in Intermetallic Alloys - Boston, MA, United States|
継続期間: 2002 12 3 → 2002 12 5
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