An Investigation on Microstructural Characteristics and Comprehensive Performances of Equiatomic Ratio NiTi Shape‐Memory Alloy Produced by Selective Laser Melting

Abstract

The present study utilizes selective laser melting (SLM) technology to fabricate NiTi alloy and investigates the deposition quality, microstructure, mechanical performances, and functional properties of the as‐deposited parts. The NiTi component is fabricated by SLM at a suitable energy density (60.61 J cm−3), resulting in favorable surface forming quality and only micron‐sized porosity defects present in the interior. Dense and fine B19’ martensite is distributed within the epitaxial B2 austenite matrix that grows in the height direction through the melt pool boundary, along with the nanoscale Ti2Ni precipitates dispersedly distribute at B19’ grain interiors and grain boundaries. Both tensile and compressive results indicate that the as‐deposited NiTi components acquire slightly inferior ductility but superior strength than that of traditionally manufactured NiTi alloys. The shape‐memory effect of NiTi components is significantly influenced by holding temperature, exhibiting good and stable shape‐memory effect above a holding temperature of 75 °C. Simultaneously, the compressive superelastic behavior of the NiTi component exhibits favorable stability, with a recoverable strain of ≈5.5%. Overall, the NiTi component fabricated in the present study exhibits favorable mechanical properties and functional performance attributed to its excellent deposition quality and dense microstructure.