Thermally-activated precipitation strengthening

Precipitation strengthening is a key strengthening method for metallic materials. However, the temperature effect on precipitation strengthening is still unclear to date. Based on dislocation theory, a thermally-activated precipitation strengthening model is built by considering the competition between shear and bypass mechanisms. For medium-sized precipitate particles, the thermally-activated shear mechanism dominates the precipitation strengthening, resulting in a plateau region. While, for large or very fine precipitate particles, the thermally-activated bypass mechanism dominates the precipitation strengthening, leading to the strengthening or weakening regions. Moreover, the effects of precipitate phase volume fraction, temperature, shear modulus, strain rate, and mobile dislocation density on precipitation strengthening are also investigated. This study not only provides new insights into precipitation strengthening from the perspective of thermal activation but also offers clear guidance for the design of new materials.