High-performance Cu-Al shape memory alloy in ternary combination with graphene fabricated by powder bed fusion process

Abstract

The main characteristic feature of Cu-based high-temperature shape memory alloys (SMAs) such as Cu-Al-Ni alloys is their high transformation temperatures that enable their applications at high temperatures. The improvement of thermodynamic properties of SMAs with reinforcements is essential for more applications at high temperatures with fewer negative effects of exposure at high temperatures, such as alloy softening that can deteriorate the strength and shape memory effect (SME) simultaneously. To avoid the negative effects of micro-reinforcements such as stress localization, in this study, graphene (GN) was substituted with Ni, and a new alloy labeled Cu-Al-GN with 0.2 wt% graphene was formed. A graphene-reinforced alloy labeled Cu-Al-Ni-GN was also fabricated by a laser powder bed fusion process for comparison purposes. The results showed that the Cu-Al-GN alloy exhibited enhanced performance in terms of improved reinforcement distribution, finer grains, defect-free samples with the highest SME at subsequent cycles, and less time required to achieve a targeted SME during heating, despite the smaller SME in the initial recovery cycles. Thus, the results of this study confirm that the proposed Cu-Al-0.2GN alloy combination promises high performance for recovery cycles and is time and cost saving, rendering it a suitable candidate for rapid production.