Overcoming the strength-ductility-wear resistance trade-off in a cast brittle Cu–20Sn–1P alloy: A solution treatment strategy

This study successfully overcame the long-standing strength-ductility-wear resistance incompatibility in a cast Cu-20Sn-1P alloy with extremely low plasticity (<1%) through a meticulously designed solution treatment strategy. Microstructural analysis revealed that the solution treatment not only dissolved the brittle Cu 41 Sn 11 phase and increased the proportion of the high-strength and high-toughness Cu 5.6 Sn phase, but also eliminated the continuous network structure of Cu 3 P. This led to an increased solid solubility of Sn and improved microstructural homogeneity. Specifically, the solution at 650°C for 40 minutes resulted in an 82.2% increase in ultimate tensile strength (UTS), and the elongation (EL) increased from 0.43% to 9.5%, compared to the semi-solid alloy before solution treatment, while simultaneously reducing the wear rate by 40%. Furthermore, it was elucidated that the metastable Cu 5.6 Sn phase forms from the Cu 17 Sn 3 phase via a non-diffusion shear transformation along the (110) <1 0> system. The orientation relationship at the Cu 3 P/Cu 5.6 Sn interface was determined to be // and // , which agrees with the Nishiyama-Wassermann ( N-W ) relationship, indicating a semi-coherent interface. Moreover, the deformation process generated dislocations, a high density of stacking faults (SFs), Lomer-Cottrell (L-C) locks, 9R phase, and deformation nanotwins (DNTs), which significantly enhanced the work hardening capacity of the alloy, thereby contributing to the superior mechanical properties and wear resistance. This work highlights the potential of utilizing a low-cost solution treatment to achieve high-performance Cu-Sn alloys and provides a crucial pathway for improving the plastic workability of high-Sn Cu-Sn alloys.