Influence of the Ar pressure on the structure of the NiTi foams produced by self-propagating high-temperature synthesis

Abstract The influence of the Ar pressure in the reactor on the structure and martensitic transformation of the NiTi foams produced by self-propagating high-temperature synthesis (SHS) was studied. It was shown that an increase in Ar pressure significantly affected the porous structure due to the process of combustion wave propagation changed from the stationary to the pulse regime. Regardless of the Ar pressure, the porous partitions included the NiTi phase as well as Ti2Ni, Ni3Ti2, Ni4Ti3 precipitates. An increase in Ar pressure decreased the transformation temperatures, which might be caused by an increase in the Ni concentration in the NiTi phase due to a decrease in the volume fraction of the Ni-rich precipitates.