Unraveling effect of Nb addition on the microstructure, phase transformation behaviour and shape memory effect of CuAlMn alloy fabricated by laser powder bed fusion

In this work, the various amount of Nb powder was mechanically mixed into the Cu-Al-Mn shape memory alloys (SMAs) to prepare quaternary SMAs by laser powder bed fusion (LPBF). Altered microstructure, transformation behaviour of alloys and its underlying mechanisms were analyzed. Corresponding shape memory effect (SME) was also studied. Result shows that Nb content has significant effect on the microstructure, phase transition temperatures (TTs) and SME. The microstructure of the alloy was refined by addition of appropriate Nb content. The formation of precipitates and massive grain boundaries after the addition of Nb caused a reduction of TTs and wide thermal hysteresis. Sample with 1 at%Nb containing fine and small volume fraction precipitate shows the best available strain.