Compressive behavior of 64% porosity NiTi alloy: An experimental study

An experimental investigation of the compressive behavior of 64% porosity NiTi alloy was undertaken in this study. Both quasi-static and low-frequency fatigue compressive tests were carried out to obtain the compressive stress-strain curves of specimens. Special attention was paid to the loading-unloading history effect on the stress-strain curves. Full-field surface deformation measurement was carried out via moiré interferometry when specimens were compressed. Inhomogeneous deformation property of the material caused by the porous structure was clearly presented. The loading-unloading history effect was also studied using the moiré interferometry method. Finally real time metallographic analysis during compression tests explained the causes of the loading-unloading history effect of the porous material from microscopic point of view. These findings are believed to be essential elements in the theoretical modeling of compressive behavior especially loading-unloading history effect of the high porosity NiTi alloy, and which still need further systematic examination in the future.