Texture of TiNi shape memory alloy sheets produced by roll-bonding and solid phase reaction from elementary metals

We have developed a new process to produce Ti-Ni shape memory alloys from titanium and nickel sheets. This process is composed of repetitive roll-bonding for producing a Ti/Ni laminated sheet from them, and of subsequent heat treatment for forming a TiNi intermetallic phase by reactive diffusion. The Ti/Ni laminated sheet changed to a nearly single phase TiNi material through the formation of Ti2Ni and Ni3Ti intermediate products. TiNi sheets obtained by this process consisted of a near <111>//ND texture such as {223}<110> in the B2 austenite phase. Recoverable strain associated with martensitic transformation of TiNi was fairly isotropic in the sheet plane due to the relatively isotropic character of {111} texture. The formation of such texture through phase transformations by reactive diffusion has been discussed in view of texture inheritance. (C) 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.