The improvement of the shape memory effect of Cu-13.5Al–4Ni high-temperature shape memory alloys through Cr-, Mo-, or V-alloying

This study presents the effect of small additions of Cr, Mo, or V on the microstructure, crystallographic features of martensitic transformation, and shape memory effect of Cu-13.5Al-4Ni master alloy. The results show that the studied alloys consist of dominant β'1 (18R) martensitic structure and fine bcc precipitates which are riched in the alloying elements but poor in the Cu content. The martensitic transformation start temperatures of the alloys are 414K, 385K, and 394K when X = 0.5Cr, 0.5Mo, or 0.5V, respectively. More importantly, a drop of grain size was achieved in the studied alloys, leading to the improvement of the shape memory effect in Cu-13.5Al-4Ni alloys. As the result, the studied alloys exhibit a steady increase of shape memory effect as the pre-strain changed from 6% to 10%, which the maximum shape memory effect reaching 6.2%, 5.8%, and 5.5% for X = 0.5Cr, 0.5Mo, and 0.5V, respectively.