Investigation of precipitation strengthening behavior of Al-Mg-Si alloy using SAXS
(1. Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
3. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;
4. State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China;
5. Collaborative Innovation Center for Advanced Ship and Deep-sea Exploration, Shanghai Jiao Tong University, Shanghai 200240, China)
2. Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China;
3. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;
4. State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China;
5. Collaborative Innovation Center for Advanced Ship and Deep-sea Exploration, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: The precipitation strengthening behavior and its effect on mechanical properties of Al-Mg-Si alloy during isothermal aging were investigated. In-situ synchrotron small angle X-ray scattering (SAXS) technique was used to characterize the nanoprecipitates and their structural parameters (size, volume fraction and number density) combined with transmission electron microscopy (TEM). The results show that rod-shaped β'''''''' precipitates grow preferentially along their longitudinal dimensions, but the radial dimension reaches a plateau after 5 h of aging. The growth of nanoprecipitates in size and volume fraction is quantitatively related to precipitation strengthening, as shown by predictions and measurements of relevant yield strength and hardness. SAXS provides more reliable input parameters for the Ashby-Orowan model, which improves the predictive accuracy and generalizability of the model. The study demonstrates that with increasing the aging time, the evolution of predictive mechanical properties of Al-Mg-Si alloy is dependent on the mean radius and volume fraction of β'''''''' precipitates.
Key words: precipitation behavior; Al-Mg-Si alloy; small angle X-ray scattering; mechanical properties