Precipitation behavior and performance evolution of cold-rolled cu-Ti-Fe alloy during heat treatment

Abstract

The CuTi alloy is extensively utilized for its high strength, excellent elasticity, and processability. Heat treatment processes are crucial for affecting the microstructure and properties. The effects of different aging processes on the microstructure and properties of cold-rolled Cu-Ti-Fe alloy were investigated, and the heat treatment parameters were optimized. The results show that the cold-rolled Cu-Ti-Fe alloy exhibits excellent comprehensive performance at 450 °C for 2 h, with the hardness of 342.2 HV, the electrical conductivity of 16.1 % IACS, and the tensile strength of 1051 MPa. The aggregation of solute atoms occurs in the early stages of aging. The uniformly distributed β'-Cu₄Ti phase precipitates at peak aging, which has a coherent relationship with the matrix. The precipitation of Ti atoms enhances the electrical conductivity of the alloy, and the movement of dislocations is prevented by precipitates, increasing the strength. During the over-aging stage, the precipitates transform into β-Cu₄Ti phases, losing complete coherency with the matrix. The coarsening of precipitates leads to the softening of the Cu-Ti-Fe alloy. Theoretical calculation results indicate that the thermal diffusion ability of solute atoms is the strongest and precipitates completely when the alloy aged at 450 °C. The precipitation strengthening mechanism plays a significant role in improving the strength.