Revealing the Stress Relaxation Mechanisms of Cu-15ni-8sn and Cu-Be Alloys

Abstract

Cu-15Ni-8Sn alloy, as a new generation of copper-based elastic alloys that can replace Cu-Be alloys, is widely used in a variety of high-temperature and high-precision mechanical fields. In this study, Cu-15Ni-8Sn (C72900) alloy was prepared using electromagnetic continuous casting, and compared to Cu-Be (C17300) alloy. The Cu-15Ni-8Sn alloy exhibited ultra-high resistance to stress relaxation performance. A detailed analysis of the microstructure before and after stress relaxation at 473 K was conducted using EBSD and TEM. The results indicate that the precipitates in the Cu-15Ni-8Sn alloy remain stable, and deformation bands are formed during the stress relaxation process, which in turn promotes subgrain recrystallization and influences subsequent deformation behavior. In contrast, the coarsening and transformation of the precipitates in the Cu-Be alloy reduce its dislocation storage capacity within the grains, leading to a significantly lower stress relaxation resistance compared to the Cu-15Ni-8Sn alloy. This study elucidates the unique mechanisms of the Cu-15Ni-8Sn alloy during the stress relaxation process, providing important theoretical insights for performance optimization in high-temperature applications.

Keywords: Electromagnetic continuous casting, Cu-15Ni-8Sn alloy, Cu-Be alloy, Stress relaxation mechanisms