Through comprehensive analysis of the microstructure

phase transformation

XRD

tensile properties

shape memory effect

and superelasticity of NiTi alloy formed by Selective Laser Melting under different heat treatment states

it was found that the mechanical properties of SLM forming NiTi alloy under the solid solution aging state were the best (tensile strength of 708 MPa

elongation of 9.9%)

the phase transformation temperature was the highest

and the precipitation strengthening phase in SLM forming NiTi alloy hindered dislocation movement

resulting in increased strength. This state can obtain a uniform supersaturated solid solution and improve the plasticity of the alloy. The shape memory performance and superelasticity of the annealed state (550 ℃

1 h

argon cooling) are the best. In addition

the design of different typical structures can also affect the recovery rate in SLM forming NiTi alloy. The highest recovery rate of the annealed NiTi alloy in the frame structure is 97% - 99%. This provides strong support for the application of NiTi alloy.