Modeling of deformation energy at elevated temperatures and its application in Mg-Li-Al-Y alloy
(1. School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China;
2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
3. Wuhu Cowin Automobile Co., Ltd., Wuhu 241000, China;
4. Xi’an Supercrystal Science and Technology Development Co., Ltd., Xi’an 710016, China;
5. Huai’an Dekema Semiconductor Co., Ltd., Huai’an 223300, China;
6. Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China)
Abstract: To control the superplastic flow and fracture and examine the variation in deformation energy, the stress and grain size of Mg-7.28Li-2.19Al-0.091Y alloy were obtained using tensile testing and microstructure quantification, and new high temperature deformation energy models were established. Results show that the grain interior deformation energy increases with increasing the strain rate and decreases with increasing the temperature. The variation in the grain boundary deformation energy is opposite to that in the grain interior deformation energy. At a given temperature, critical cavity nucleation energy decreases with increasing strain rate and cavity nucleation becomes easy, whereas at a given strain rate, critical cavity nucleation energy increases with increasing temperature and cavity nucleation becomes difficult. The newly established models of the critical cavity nucleation radius and energy provide a way for predicting the initiation of microcrack and improving the service life of the forming parts.
Key words: high temperature deformation; superplasticity; creep; deformation energy; Mg-Li-Al-Y alloy