Effect of cryogenic treatment on the aging kinetics and properties of CuNiSiCr alloy

Abstract In this study, a commercially extruded CuNiSiCr alloy was subjected to a solution treatment at 900 °C for 60 min, followed by rapid cooling using conventional water quenching and cryogenic cooling methods. The samples were then aged at 450 °C for 0–240 min. Metallurgical analyses revealed the presence of Ni/Cr-rich metal silicides within the α-Cu matrix, and it was determined that Cr-rich precipitates did not fully dissolve during the solution treatment due to their high-temperature stability. Electrical conductivity measurements showed a decrease in conductivity values after quenching in the supersaturated matrix, but significant increases in conductivity were observed with aging time. Cryogenic cooling accelerated the precipitation kinetics, enabling the attainment of higher conductivity (24.09 MS m −1 ) and hardness (247 HV) values in a shorter time. Using the Avrami kinetic model, precipitation volume fractions and phase transformation rates were calculated, confirming that cryogenic cooling accelerates the aging process. The findings demonstrate that cryogenic cooling combined with appropriate aging optimizes the microstructure and phase distribution of the CuNiSiCr alloy, improving key properties such as electrical conductivity and mechanical hardness, thereby providing superior performance for commercial applications.