Processing of TiNi from elemental powders by hot isostatic pressing

A procedure for producing cylindrical samples of TiNi shape memory alloy wa s desired in order to be able economically to provide thermomechanical test specimens to support a constitutive and behavioral modeling effort. The in itial development and results of such a procedure are presented in this wor k. Elemental powders were mixed to ratios of 50.0 and 50.6 at.% Ni, packed and sealed into stainless steel containers. hot isotatically pressed (HIPed ) at 200 MPa and 900-1050 degrees C, and machined to expose a gauge section of consolidated TiNi material for thermomechanical testing. Some samples o f material were used for DSC analysis to determine transformation temperatu res as well as for microscopic examination. Effects of HIPing and post-cons olidation heat treatments on the material microstructure and transformation behavior were measured via SEM and DSC analyses. Specimens of approx. 99% theoretical density and nearly homogeneous TiNi microstructures were produc ed. The specimens were mechanically tested in tension and compression and w ere shown to exhibit moderate degrees of the shape memory effect and pseudo elasticity. Published by Elsevier Science S.A.