First investigation on processing parameters for laser powder bed fusion of Ni-Mn-Ga magnetic shape memory alloy

The Ni-Mn-Ga alloy develops strains of several percents in an applied magnetic field. These materials have potential as high-speed actuators, valves, pumps, robots, and microgrippers. Laser powder bed fusion (L-PBF) of Ni-Mn-Ga was investigated in order to establish a preliminary processing window and to understand the effects of processing parameters on end-product composition. In the future, L-PBF could enable the production of functional near net shape Ni-Mn-Ga components on an industrial scale. A series of experiments were conducted for prealloyed Ni-Mn-Ga powder using an L-PBF setup developed in-house. Two different substrate materials, stainless steel 316L and Incoloy 825, were used in the experiments. The single track experiments show that tracks deposited on Incoloy substrates, in comparison to tracks deposited on stainless steel substrates, are wider and have shallower penetration into the substrate. In addition, the tracks deposited on the Incoloy substrates are more likely to exhibit irregular and balling morphologies. The results of the single track and hatching distance experiments were used to manufacture Ni-Mn-Ga cuboids on an Incoloy substrate. Analysis of the cuboid compositions revealed that L-PBF of Ni-Mn-Ga dilutes manganese and gallium. The relative amounts of vaporized manganese and gallium increased as the value of volumetric energy density was increased.