Abstract: Binder jetting has shown promise for the rapid preparation of brittle Ni-Mn-based alloy parts, while the effect of residues on martensitic transformation (MT) behavior has rarely been studied. Here, binder-jetted and sintered Ni-Mn-Sn-Co alloys with different residue content were prepared. In a 2 h sintered alloy, interstitial-oxygen-induced γ-phase precipitation was found. Owing to its intrinsic hardness and lattice mismatch with the matrix, the γ phase hindered the movement of MT fronts, and internal stress fields developed in the matrix, which increased the hysteresis and MT width, and decreased the MT temperature. In a 16 h sintered alloy, at a low residual oxygen content, the γ phase dissolved in the matrix, rejuvenating MT behavior. This work improves our understanding regarding the effect of residues on the properties of Ni-Mn-Sn-Co alloys produced through binder-based additive manufacturing, and proposes a strategy for regulating the MT behavior of such alloys.

Key words: Additive manufacturing (AM), Binder jetting (BJ), Sintering, Magnetic shape memory alloys (MSMAs), Martensitic transformation (MT) behavior