In-situ formation of Cu4(Sc, Zr) with deformation-induced precipitation enhances the comprehensive properties of Cu-Cr-Zr-Sc alloys

This study utilized Sc doping to form a new intermetallic compound and was combined with SRA (Solution + 75 % Rolling + Aging) process to control the in-situ formation of the Cu₄(Sc, Zr) phase and its precipitation behavior at micro and nano scales, thereby enhanced the comprehensive properties of the alloy. Compared to the normal SA (Solution + Aging) process, the SRA (Solution + 75 % Rolling + Aging) process is more conducive to the simultaneous improvement of mechanical and electrical properties. When the Sc content is 0.15 %, under the SRA peak aging condition (400 ℃ × 4 h), the hardness, electrical conductivity, and strength were 196.45 ± 2.16 HV, 72 % IACS, and 540.79 ± 10.1 MPa, respectively. The alloy maintained high strength and hardness under small rolling reduction due to the fine dispersion of the Cu₄(Sc, Zr) phase at small sizes (∼5.27 μm) at the micron scale (∼0.41 %) and nanoscale precipitation. The nanoscale Cu₄(Sc, Zr) phase forms based on substitution in the Cu₄Sc crystal structure. After the SRA process, an orientation relationship of ${\left[110\right]}_{\text{Cu}}//{\left[012\right]}_{{\text{Cu}}_4(\text{Sc},\text{Zr})}$,${\left(\bar{1}1\bar{1}\right)}_{\text{Cu}}//{\left(100\right)}_{{\text{Cu}}_4(\text{Sc},\text{Zr})}$between the Cu₄(Sc, Zr) phase and the matrix is established, and its size is significantly refined, with stacking faults observed internally. The orientation relationship of the Fcc-Cr phase changed from ${\left[\bar{1}12\right]}_{\text{Cu}}//{\left[011\right]}_{\text{Cr}}$, ${\left(\bar{1}1\bar{1}\right)}_{\text{Cu}}//{\left(\bar{2}00\right)}_{\text{Cr}}$ in the peak aging state of the SA process to a Cube-on-Cube. This indicates that deformation processes can alter the orientation relationships of precipitates, and the presence of metastable phases contributes to improving the comprehensive properties of the alloy.