Influence of aging temperature on the microstructure and mechanical properties of a Cu-2Be alloy

Abstract

As a contribution to existing knowledge, this work studied the evolution of the hardness, elastic modulus and microstructure of an age-hardenable Cu-2Be alloy when subjected to aging treatments at different times, in order to obtain the hardness curves at all stages, and for different aging temperatures in the range of 320–400 °C. In addition, the effect of performing a prior heat treatment consisting of 2 h at 225 °C on the mechanical behavior of the material was analyzed. The elastic modulus and hardness were measured using IET technique and Vickers hardness, respectively. The best mechanical properties (higher hardness values and high elastic modulus) were obtained for treatments at aging temperatures of 320 and 350 °C, with aging times of 40 and 5 h, respectively. The maximum hardness decreases with temperature and increases by about 25 HV by performing a prior thermal treatment at 225 °C. At the maximum hardness peaks, the elastic modulus exhibits similar values, while the asymptotic value increases slightly with temperature. SAXS measurements were used to study the size and shape of the nanoprecipitates formed after aging treatments at different temperatures and times. At the hardness peaks, precipitates have ellipsoid shapes and their size increases with the temperature from 18 to 30 nm. After the hardness peak at 400 °C, the hardness and modulus decrease slightly, while the precipitate size increases to 58 nm.