Space-holder engineered porous NiTi shape memory alloys with improved pore characteristics and mechanical properties

In this study, porous Ti-50.8 at.% Ni shape memory alloys (SMAs) with tailored pore characteristics and porosities as well as adjustable mechanical properties were successfully prepared by using a novel poreforming technique and powder sintering process. The results show that the use of the sieved NH4HCO3 particle (i.e., the space-holder) greatly facilitates the fabrication of porous NiTi alloys with more satisfactory pore features, improved pore size-uniformity and distribution, and thus significantly increased mechanical properties (including excellent linear superelasticity) than that using no-sieved NH4HCO3 powder. It is also shown that pore size of the space-holder engineered porous NiTi alloys increases correspondingly with the size of sieved NH4HCO3 particles added, and there exists a geometrical heredity effect of space-holder NH4HCO3 particles on pore shape and size of the porous NiTi alloys. (C) 2008 Elsevier B.V. All rights reserved.