Ion nitriding of TiNi shape memory alloys .1. Nitriding parameters and microstructure characterization

[摘要] Ti50Ni50 and Ti50Ni40Cu10 shape memory alloys were ion nitrided to modify the surface conditions. The phases and microstructures of the nitrided surface were studied by XRD, EPMA and SEM. Experimental results indicate that the nitrided compound layer of equiatomic TiNi alloy consists of TiN and Ti2Ni phases, and that of Ti50Ni40Cu10 alloy consists of TiN, Ti2N and Ti-40(Ni,Cu)(60) phases. The surface hardness and the compound layer thickness increase with increasing nitriding temperature and time. These nitrided compound layers are found to exhibit a slight depression on the alloys' martensitic transformation temperatures and their shape recovery ability. A mechanism to explain the formation of the ion-nitrided layer in equiatomic TiNi alloy is also proposed in this study. (C) 1997 Elsevier Science S.A.

[发布日期] 1997-07-01

[关键词] shape memory alloys;ion nitriding;TiNi alloys