Microstructure and mechanical properties of niti‐based eutectic shape memory alloy produced via selective laser melting in‐situ alloying by nb

Abstract

This paper presents the results of selective laser melting (SLM) process of a nitinol‐based NiTiNb shape memory alloy. The eutectic alloy Ni45Ti45Nb10 with a shape memory effect was obtained by SLM in‐situ alloying using a powder mixture of NiTi and Nb powder particles. Samples with a high relative density (>99%) were obtained using optimized process parameters. Microstruc-ture, phase composition, tensile properties, as well as martensitic phase transformations temperatures of the produced alloy were investigated in as‐fabricated and heat‐treated conditions. The NiTiNb alloy fabricated using the SLM in‐situ alloying featured the microstructure consisting of the NiTi matrix, fine NiTi+β‐Nb eutectics, as well as residual unmelted Nb particles. The mechanical tests showed that the obtained alloy has a yield strength up to 436 MPa and the tensile strength up to 706 MPa. At the same time, in‐situ alloying with Nb allowed increasing the hysteresis of marten-sitic transformation as compared to the alloy without Nb addition from 22 to 50 °C with an increase in Af temperature from −5 to 22 °C.