Diffusion kinetics for fcc quinary Cu–Co–Mn–Ni–Si system and its application to precipitation simulations

Abstract

The accurate diffusivity and kinetic database of fcc quinary Cu–Co–Mn–Ni–Si system is essential for designing high-performance Cu alloys, which is still not investigated yet. In the present work, on the basis of the critically reviewed experimental diffusivities available in the literature, the atomic mobilities of fcc Mn–Ni and Cu–Mn–Ni alloys were re-assessed through CALTPP (CALculation of ThermoPhysical Properties) program, aiming to establish a self-consistent kinetic database for fcc Cu–Co–Mn–Ni–Si system. Comparing the model-calculated diffusion coefficients, composition profiles and diffusion paths with the measured ones for fcc Mn–Ni and fcc Cu–Mn–Ni alloys, it is found that the experimental data are reasonably reproduced by the re-assessed atomic mobilities, indicating their good reliability. Therefore, integrating the presently obtained atomic mobilities for the fcc Mn–Ni and fcc Cu–Mn–Ni systems with those for other sub-systems, a complete kinetic database for fcc Cu–Co–Mn–Ni–Si system was established for the first time. The reliability of the constructed kinetic database was confirmed by the reasonable agreements between the model-predicted composition profiles of sub-quaternary and quinary diffusion couples and the measured ones. Furthermore, this obtained kinetic database was applied to simulate the microstructure evolution of second-phase precipitates in Cu–Mn–Ni, Cu–Ni–Si and Cu–Ni–Co–Si alloys during the aging process, and the simulated results demonstrate good agreements with the experimental ones. The present work indicates the reliability and significance of the presently obtained kinetic database of fcc quinary Cu–Co–Mn–Ni–Si system for predicting the microstructure evolution during the heat treatment process, which can greatly contribute to the design of Cu alloys with high performance.