Abstract: This work systematically studied the effect of volumetric energy density E on the densification, microstructures, tensile mechanical properties, and shape memory performance of a Fe-Mn-Si-Cr-Ni shape memory alloy (SMA) fabricated by laser powder bed fusion (L-PBF). An E of 90-265 J/mm³ is suggested to fabricate the Fe-Mn-Si-Cr-Ni SMA with minor metallurgical defects and a high relative density of above 99%. The increase in E can promote the formation of the primary γ austenite and the solid phase transformation from the primary δ ferrite to the γ austenite, which helps to achieve a nearly complete γ austenitic microstructure. The increase in E also contributes to fabricating the Fe-Mn-Si-Cr-Ni SMA with superior comprehensive mechanical properties and shape memory performance by L-PBF. The Fe-Mn-Si-Cr-Ni SMA with a combination of good ductility of around 30%, high yield strength of above 480 MPa, an ultrahigh ultimate tensile strength of above 1 GPa, and large recovery strain of about 6% was manufactured by L-PBF under a high E of 222-250 J/mm³. The good shape memory effect, excellent comprehensive mechanical properties, and low cost of Fe-Mn-Si-Cr-Ni SMAs, as well as the outstanding ability to fabricate complex structures of L-PBF technology, provide a solid foundation for the design and fabrication of novel intelligent structures.

Key words: Shape memory alloys, Fe-Mn-Si-based alloys, Laser powder bed fusion, Mechanical property, Microstructure