Abstract: Ni-Mn-Ga magnetic shape memory alloys possess multifunctional properties. Nevertheless, the intrinsic brittleness of Ni-Mn-Ga alloys greatly limits their capability to be manufactured into complex shapes in order to meet practical use, by employing traditional mechanical processing methods. “Hard-to-weld” Ni-Mn-Ga green parts are prepared by using binder jetting additive manufacturing (BJAM) technique. Densification, compositions, microstructures, martensitic transformation (MT) behaviours, and magnetic properties of parts sintered at 1 193 ～ 1 323 K are investigated. The sintering temperatures have negligible effect on the chemical composition, and a homogeneous L2₁-ordered austenite structure is identified in all sintered samples at room temperature; The relative density and linear shrinkage rate of the final parts increases from 56.8% to 85.9% and 0.5% to 17.8%, respectively, meanwhile, a decrease of MT temperatures, and an increase of MT width and hysteresis are characterized, as the increase of sintering temperatures. A maximum saturation magnetization of 74.4 A·m²/kg is achieved under 1.5 T in the preferred sample sintered at 1 223 K for 8 h, which reaches the level of Ni-Mn-Ga alloys prepared by traditional methods, and is the highest value reported in current literatures of additive manufactured counterparts as well. This work provides an important technical reference for BJAM of functional Ni-Mn-Ga alloy devices with complex shape.

Key words: Ni-Mn-Ga magnetic shape memory alloys, binder jetting additive manufacturing (BJAM), sintering temperature, Martensitic transformation (MT), magnetic property