Insights into the role of chemical composition on the precipitation kinetics and properties of L12-strengthened Cu–Ni–Al alloys: A thermodynamic-driven phase field kinetics simulation

Abstract

Abstract

Cu–Ni–Al alloys represent a novel class of L1 2 -strengthened Cu-based alloy, offering enhanced thermal stability and high temperature mechanical properties. However, the influence of chemical composition on the precipitation kinetics of the L1 2 phase remains insufficiently understood. In this study, the microstructural evolution and elemental partitioning behavior of Cu–Ni–Al alloys during aging were investigated using a developed phase field model. Our calculations indicate that the coarsening rate of the L1 2 phase first decreases and then increases with rising Al + Ni content, exhibiting a “V-shaped” trend attributed to the competition between thermodynamic and kinetic factors. Additionally, both the number density and volume fraction of the L1 2 phase increase with increasing Al + Ni content. Elemental analysis indicates that both Al and Ni are enriched in the L1 2 precipitates, driven by chemical potential difference. Based on the simulated microstructure and elemental distribution, the precipitation strengthening contribution and electrical resistivity were quantitatively evaluated. The results demonstrated that precipitation strengthening increases with increasing Al + Ni content, primarily due to the increased volume fraction of the L1 2 phase. Meanwhile, the electrical resistivity also increases with increasing Al + Ni content, mainly attributed to the elevated Ni concentration in the Cu matrix. These findings provide valuable insights for designing and developing advanced Cu–Ni–Al alloys with tailored microstructural stability, mechanical properties, and electrical conductivity.