中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 30 No. 9 September 2020 |
（National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract:The microstructure and mechanical properties at different depths of squeeze-cast, solution-treated and aged Al-5.0Mg-3.0Zn-1.0Cu alloy were investigated. For squeeze-cast alloy, from casting surface to interior, the grain size of α(Al) matrix and width of T-Mg32(AlZnCu)49 phase increase significantly, while the volume fraction of T phase decreases. The related mechanical properties including ultimate tensile strength (UTS) and elongation decrease from 243.7 MPa and 2.3% to 217.9 MPa and 1.4%, respectively. After solution treatment at 470 °C for 36 h, T phase is dissolved into matrix, and the grain size increases so that the UTS and elongation from surface to interior are respectively reduced from 387.8 MPa and 18.6% to 348.9 MPa and 13.9%. After further peak-aging at 120 °C for 24 h, numerous G.P. II zone and η′ phase precipitate in matrix. Consequently, UTS values of the surface and interior increase to 449.5 and 421.4 MPa, while elongation values decrease to 12.5% and 8.1%, respectively.
Key words: squeeze-cast Al-Zn-Mg-Cu alloys; solution treatment; aging; microstructures; mechanical properties
