Non-equilibrium microstructure and the metastable phase of Al-9.6wt%Mg alloy solidification under high pressure

作者：Wei Zunjie; Wang Zhenling; Wang Hongwei; Zhu Zhaojun; Cao Lei; Li Zhiwei

来源：Rare Metals, 2007, 26: 231-236.

• high pressure solidification
• microstructure
• metastable phase
• Al-9.6wt%Mg alloy

The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope, differential scanning calorimetry, X-ray diffraction and transmission electron microscope. The results showed that dendrite microstructure was refined, and the solid solubility of Mg in alpha-Al phase increased greatly. Correspondingly, the lattice parameter of alpha-Al phase increased. Al3Mg2 phases disappeared under high pressure solidification. In particular, a metastable phase with small size (20 nm or so) was produced in the alloy, its melting temperature range was 464 similar to 518.2 degrees C, which was higher than that of Al3Mg2 phase (453 similar to 465 degrees C) under normal pressure. These metastable phases located in the interdendritic position. It was the first time that the metastable phase was found in Al-Mg alloy at a high pressure of 6 GPa. The formation mechanism of the metastable phases was discussed.

• 出版日期2007-8
• 单位哈尔滨工业大学