Excellent superelasticity in a Co-Ni-Ga high-temperature shape memory alloy processed by directed energy deposition

Abstract

A Co-Ni-Ga high-temperature shape memory alloy has been additively manufactured by directed energy deposition. Due to the highly anisotropic microstructure, i.e. columnar grains featuring a strong near-⟨001⟩ texture in build direction, the as-built material is characterized by a very low degree of constraints and, thus, shows excellent superelasticity without conducting a post-process heat treatment. As characterized by in situ deformation testing and post-mortem microstructural analysis, additive manufacturing employing directed energy deposition seems to be highly promising for processing of shape memory alloys, which often suffer difficult workability.

Keywords

• high-temperature shape memory alloys
• additive manufacturing
• laser melting
• pseudoelasticity
• direct microstructure design