Design, preparation and printability of Ni-Co-Mn-Al-Y shape memory alloy powder for LAM

Laser additive manufacturing (LAM) is a new and effective method to prepare magnetic shape memory alloys (MSMAs) with complex structures, but magnetic shape memory alloy powders suitable for LAM need to be developed. In this study, a new Ni-Co-Mn-Al-Y alloy composition was developed, and the alloy powder was prepared by vacuum induction melting gas atomization, and the alloy samples were prepared by LAM. The results showed that the best comprehensive characteristic of Ni-Co-Mn-Al-Y alloy powder was obtained at the final melting temperature of 1898 K and the atomization pressure of 11.0 MPa, with a particle size range of 1–120 μm, 98.9 ± 0.1% sphericity, 1.8% hollow sphere rate, flowability of 26.2 ± 0.4 s/50 g, and apparent density of 4.1 ± 0.01 g/cm³. The influence of atomization pressure on powder morphology is mainly due to the atomization pressure on the collision of droplets and the interaction between droplets and airflow. The Ni-Co-Mn-Al-Y alloy prepared by LAM underwent a reversible martensitic transformation after heat treatment, exhibiting an adiabatic temperature change of −1.7 K at a high temperature of 400 K. The alloy compositions, powdering process, and forming process can be used as a reference for the preparation of high-performance MSMAs by LAM.