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采用光学显微镜对Mg-xGd-2Y-0.5Zr(x=9,11,13,15 mass%)合金铸态、固溶时效态以及拉伸断口附近纵切面组织进行观察分析,并用扫描电镜和电子拉伸试验机分别对合金断口形貌和不同温度下的力学性能进行测试和分析。研究结果表明:铸态Mg-xGd-2Y-0.5Zr合金经525℃固溶6 h和225℃时效10 h后粗大的枝晶消失,晶界清晰可见;当Gd的添加为13 mass%时,合金的晶粒最细小,组织分布最均匀,Mg-13Gd-2Y-0.5Zr合金具有优异的室温和高温力学性能,其在室温和高温下的抗拉强度达到最大值。当Gd的含量一定时,合金的抗拉强度随拉伸温度的升高先升高后降低,在250℃时达到最大值;Mg-13Gd-2Y-0.5Zr合金断裂形式为脆性断裂,并以沿晶断裂为主。
The microstructure of Mg-xGd-2Y-0.5Zr alloy (x = 9, 11, 13 and 15 mass%) cast in as-cast, solution-aged and tensile fracture near the longitudinal section was observed by optical microscopy. Tensile testing machine respectively, the fracture morphology and mechanical properties at different temperatures were tested and analyzed. The results show that the coarse dendrite disappears after aging at 525 ℃ for 6 h and aging at 225 ℃ for 10 h, and the grain boundaries are clearly visible. When the Gd content is 13 mass%, the as-cast Mg-xGd-2Y- The grain size of the alloy is the smallest and the microstructure is most uniform. The Mg-13Gd-2Y-0.5Zr alloy has excellent mechanical properties at room temperature and high temperature, and its tensile strength reaches the maximum at room temperature and high temperature. When the content of Gd is constant, the tensile strength of the alloy first increases and then decreases with the increase of the stretching temperature and reaches the maximum at 250 ℃. The rupture of Mg-13Gd-2Y-0.5Zr alloy is brittle fracture, Fracture-based.