Thermodynamically Guided Improvement of Fe-Mn-Al-Ni Shape-Memory Alloys

A microstructural informed thermodynamic model is utilized to tailor the pseudoelastic performance of a series of Fe-Mn-Al-Ni shape-memory alloys. Following this approach, the influence of the stability and the amount of the B2-ordered precipitates on the stability of the austenitic state and the pseudoelastic response is revealed. This is assessed by a combination of complementary nanoindentation measurements and incremental-strain tests under compressive loading. Based on these investigations, the applicability of the proposed models for the prediction of shape-memory capabilities of Fe-Mn-Al-Ni alloys is confirmed. Eventually, these thermodynamic considerations enable the guided enhancement of functional properties in this alloy system through the direct design of alloy compositions. The procedure proposed renders a significant advancement in the field of shape-memory alloys. The utilization of a microstructural-informed thermodynamic model enables the creation of pseudoelastic Fe-Mn-Al-Ni shape-memory alloys with enhanced reversibility. The feasibility of the proposed alloy-design strategy is proven by complementary spherical nanoindentation and in situ compression tests. The innovative computational-thermodynamics approach allows a direct composition design for improved functional properties, marking a substantial advance in shape-memory alloy research.image