Effects of Remelting on the Properties of a Superelastic Cu-Al-Mn Shape Memory Alloy Fabricated by Laser Powder Bed Fusion

Laser powder bed fusion (LPBF) constitutes a promising alternative to directly produce Cu-based shape memory parts with high superelasticity due to the fact that the grain size and morphology as well as the texture can be tailored during processing. It is known that immediate laser remelting of previously processed layers during LPBF can serve as an important and complementary method to improve part density and to adjust the microstructure and mechanical behavior. As a consequence, this study focuses on the effects of an additional remelting step on the material properties of an additively fabricated Cu71.6Al17Mn11.4 (at.%) shape memory alloy (SMA). Firstly, the effects of different remelting parameters, obtained via systematically changing the hatching distance and scanning speed, on the sample density and transformation temperatures were analyzed. Secondly, microstructural observations as well as incremental compression tests were performed to establish the relationships between the applied remelting process parameters, the microstructure, and the superelastic properties. The comparison of the results for remelted and non-remelted counterparts clearly proves that a subsequent exposure of already solidified layers can serve as an adaptive tool to improve the performance of Cu-based SMAs and to allow the fabrication of locally adapted shape memory parts for application-oriented scenarios.