Fabrication of FeMnSi-based shape memory alloy components with graded-microstructures by laser powder bed fusion

This work demonstrates the tailoring of the microstructure of two FeMnSi-based shape memory alloys during laser powder bed fusion. Significant variations in the microstructure of the parts can be induced by modifying the scanning speed or the scanning strategy during the process. Specifically, the volume phase fractions, texture, and grain size and morphology change with the applied processing parameters as the thermal history experienced by the material is modified. Additionally, the generally undesired Mn evaporation during laser melting can be deliberately exploited to manipulate the phase composition in the final microstructure. Taking advantage of this, graded-microstructure samples with tailored amounts of the two phases (bcc-δ and fcc-γ) and distinct microstructure at different locations can be fabricated. A good combination of pronounced shape memory effect and ultrahigh strength can be achieved in this way. The findings of this study offer valuable insights that can drive future research and advancements in additive manufacturing, opening exciting opportunities for the fabrication of multifunctional and high performance materials.