中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 18 No. 3 June 2008 |
（1. School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China;2. Materials Science Division, Argonne National Laboratory, Argonne, IL60439, USA）
Abstract:The phase selection of ternary intermetallic compound τ phase (Mg32(Al, Zn)49 ) and φ phase (Al2Mg5Zn2) in high zinc magnesium alloys was studied by using scanning electron microscope, X-ray diffractometer and differential scanning calorimeter, etc. The results indicate that, when adding element Si in Mg-8Zn-4Al-0.3Mn (ZA84) alloy, φ phase is promoted, whereas τ phase is inhibited. The Chinese script-type Mg2Si and matrix microstructure are greatly refined, the formation of τ phase is facilitated and φ phase is restrained when modifier Al-AlP master alloy is added in ZA84 alloy containing Si. The kinetics study of phase selection indicates that there is a critical degree of undercooling of the melt. If the undercooling exceeds the critical value, τ phase preferentially forms while φ phase is restrained; otherwise, φ phase preferentially forms while τ phase is restrained.
Key words: high-zinc magnesium alloy; Si; AlP; phase selection; kinetics
