Effect of thermal exposure on microstructure and mechanical properties of Al-Si-Cu-Ni-Mg alloy produced by different casting technologies
(1. National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China;
2. School of Mechanical and Ocean Engineering, Jiangsu Ocean University, Lianyungang 222005, China;
3. GRIMAT Engineering Institute Co., Ltd., Beijing 101407, China;
4. Institute of Materials for Mobile Energy, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
2. School of Mechanical and Ocean Engineering, Jiangsu Ocean University, Lianyungang 222005, China;
3. GRIMAT Engineering Institute Co., Ltd., Beijing 101407, China;
4. Institute of Materials for Mobile Energy, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: The effect of thermal exposure at 350 °C for 200 h on microstructure and mechanical properties was investigated for Al-Si-Cu-Ni-Mg alloy, which was produced by permanent mold casting (PMC) and high pressure die casting (HPDC). The SEM and IPP software were used to characterize the morphology of Si phase in the studied alloys. The results show that the thermal exposure provokes spheroidization and coarsening of eutectic Si particles. The ultimate tensile strength of the HPDC alloy after thermal exposure is higher than that of the PMC alloy at room temperature. However, the TEPMC and TEHPDC alloys have similar tensile strength around 67 MPa at 350 °C. Due to the coarsening of eutectic Si, the TEPMC alloy exhibits better creep resistance than the TEHPDC alloy under studied creep conditions. Therefore, the alloys with small size of eutectic Si are not suitably used at 350 °C.
Key words: Al-Si-Cu-Ni-Mg alloy; thermal exposure; coarsening; creep behavior