Effect of Heat Treatment on Structure and Magnetic Properties of Ni36co37al27 Alloy Produced by Laser Powder Bed Fusion

In this paper the effect of heat treatment on the structure and magnetic properties of Ni36Co37Al27 alloy obtained by laser powder bed fusion from powders synthesized by mechanical alloying and plasma spheroidization was studied. This alloy is promising to exhibit a magnetically controlled shape memory effect at room temperature. It was shown that the base of the alloy was two-phase (β + γ). Sizes of the structural elements increases with a rise in annealing temperature (Tann), however, the ratio of γ- to β-phase decreases from Tann = 900 °С to Tann= 1300 °С, which agrees well with the observed monotonic decrease in saturation magnetization. It was also found that Hc of the alloy increases from 74.9 Oe in non-heat-treated state to about 120 Oe after the heat treatment, which is due to a decreased content of γ-phase in combination with the precipitation of γ'-phase inclusions. The results obtained can be used in the future to manipulate the high-coercivity properties of Ni-Co-Al alloys at different stages of additive manufacturing.