Production of Porous NiTi Bulk Shape Memory Alloy by Starch Consolidation and Sintering of Pre-Alloyed Powder

摘要

Starch consolidation is water based direct consolidation technique, which allows the fabrication of porous structures. Starch consolidation followed by solid state sintering was successfully used to fabricate porous samples with controlled porosity and shape from pre-alloyed NiTi powder as starch acts as binder and pore former during consolidation. Microstructural investigations, X-ray diffraction measurements and differential scanning calorimetry measurements were performed in order to characterize the powder and sintered products. The mechanical properties were investigated by compression tests and cyclic loading tests at room temperature. The microstructure of sintered sample consists of Ni_4Ti_3 and TiC precipitates besides NiTi phase. The sintered samples displayed high compression yield strength of about 1 GPa with high plastic deformation of about 35%. Shape memory effect of sintered samples was examined after cyclic loading which shows that the sintered samples display shape memory effect. This shows that the starch consolidation followed by sintering is a promising method to build porous functional materials such as filter inserts and cancellous bone implants.