Numerical investigation of sintering porous NiTi shape memory alloy by self-propagating high-temperature synthesis

In this paper, large-scale porous NiTi shape memory alloy (SMA) sintered by self-propagating high-temperature synthesis (SHS) has been investigated numerically. The SHS reaction process could be divided into three steps: preheating, ignition and sintering. The mathematical model about ignition and sintering were constructed to investigate the effect of the preheating temperature and the initial degree of conversion on the combustion. The results showed that the SHS reaction could not be completed for large initial degree of conversion. The critical preheating temperature for completed combustion was also obtained for different initial degree of conversion. It needed at least 573 K to complete the combustion for the initial degree of conversion 0.215, and 873 K for the initial degree of conversion 0.56. The mean wave velocity increased with the increase of preheating temperature and decreased with the increase of the initial degree of conversion.