Controlled Precipitation and Strengthening in a CuFeNiMn High-Entropy Alloy

A novel precipitation-strengthened CuFeNiMn high-entropy alloy without sigma-sensitive Cr and rare Co was prepared by traditional cast, homogenization, cold rolling and aging. The second phase was controllably precipitated by aging, which was identified as Cu-rich face-centered-cubic (FCC) phases, distributed dispersedly in the FCC-structured matrix. Two characteristic aging parameters were selected to study the precipitate features and corresponding tensile properties. After aging at 800 °C/1 h, the alloy exhibits a good integrated performance, i.e. tensile yield strength, ultimate tensile strength, and elongation of 825 MPa, 932 MPa, and 18%, respectively. Increasing the aging temperature to 900 °C, the yield strength is decreased significantly, but the work hardening rate and elongation are increased. The Cu-rich particles play a predominant part in strengthening by dislocation shearing, different from the by-pass mechanism of the hard ceramic and intermetallic precipitates.