Dimensions were measured on 52at%Ni/48at%Ti mixed powder compacts at several stages through the process of pressing and sintering to know how to make precision NiTi parts in a convensional powder metallurgical process. The cubic compacts 5mm in size were pressed under 200-800MPa, heated up in argon at the rates of 2K/min or 5K/min or through the 10K/min-2K/min-10K/min program, and held at 1323K for 60min.
Slower heating in the exothermic reaction temperature range resulted in lighter deformation. The dimensional change was found to be anisotropic. Compacts were observed to expand to reach a peak value and then shrink. This change proceeded earlier in the compacting direction than in the lateral direction. For the compacts pressed at 800MPa, the final dimensional change was shrinkage in the compacting direction and expansion in the lateral direction.