Tunable Intelligent Properties and Anisotropy of Ni50.8ti49.2 Alloy Fabricated by Laser Powder Bed Fusion Through Solution Treatment and Structural Design Strategies

Abstract

Compared with the conventional near-equiatomic NiTi alloy, the NiTi alloy fabricated by additive manufacturing has the advantages to make the fabrication of porous and complex shape NiTi parts possible and provide an ability to control the level of porosity, pore size and shape. Furthermore, adjusting the processing parameters of additive manufacturing and heat treatment is also a common way to improve its intelligent properties and anisotropy. In this work, Ni 50.8 Ti 49.2 alloys of high quality were fabricated by laser powder bed fusion. The microstructure of as built Ni 50.8 Ti 49.2 alloy varied with building heights, and the anisotropy of microstructure changed after heat treatment. The optimal superelastic recoverable strain of the as built samples was 7.0%, and that of the solution-treated sample was up to 7.48%, while the anisotropy of the intelligent property was greatly reduced after solution treatment. Honeycomb structure is well-known for its application in damping and impact resistant with high strength/mass ratio. Therefore, based on the excellent properties explored, complex Ni 50.8 Ti 49.2 honeycomb structure was manufactured. It is really worth noting that the superelastic strain recovery rate of this honeycomb structure perpendicular to the honeycomb hole axis is 97% when compressive strain as high as 30% is applied. Simultaneously, the recovery strain of shape memory effect is 6.08% for cast ingot, while that of honeycomb is 7.3%.

Keywords: laser powder bed fusion, Ni50.8Ti49.2, Anisotropy, Intelligent Properties, Structural Design