Microstructure and Properties of Cu–Al–Fe Shape Memory Alloy with Gradient Structure Fabricated by Electron Beam Melting

Abstract

In this study, a Cu–13Al–5Fe (wt %) shape memory alloy with a gradient structure was produced using electron beam melting (EBM) technology. A systematic investigation of its microstructure, shape memory effect, and mechanical properties was carried out. The results revealed that the EBM resulted in the difference in structure, with the grain size in the as-cast upper part of the ingot measuring 180 ± 60 μm, while in the lower part it reached 320 ± 100 μm. In quenched specimens taken from both the upper and lower parts of the ingot, treated at 850°C, a martensitic transformation (β₁ → \(\beta _{1}^{'}\)) was observed, initiating at 501 ± 3°C. The tensile strength of the quenched specimen from the upper part of the ingot was determined to be 541 ± 20 MPa, compared to 335 ± 18 MPa for the as-cast specimen. In the lower part of the ingot, the tensile strength of the quenched specimen was higher than that of the as-cast specimen, reaching 641 ± 15 MPa. Additionally, the shape memory recovery coefficient of the quenched specimen from the upper part of the ingot, subjected to 3% pre-strain, was 91.9%. This study establishes a basis for the application of EBM technology in the fabrication of Cu–Al–Fe-based shape memory alloys.