【摘要】 研究了Mg-5Gd-1Mn-0.3Sc合金铸态显微组织及在520℃固溶处理不同时间后的组织结构演变行为。结果表明,合金铸态组织表现为粗大的枝晶结构,晶界上或枝晶之间都分布着大量的富溶质相,其中相当数量的GdMg3相在非平衡凝固过程中生成,而在固溶处理中并未消除。合金经520℃不同时间固溶处理,晶粒尺寸变化异常。固溶14 h后晶粒尺寸减小到铸态的1/3,继续延长固溶时间,晶粒尺寸重新变大。因此控制固溶温度和时间,可获得试验合金晶粒细化的效果。更多还原

【Abstract】 The microstructure of Mg-5Gd-1Mn-0.3Sc as cast alloy and its evolution behavior after solution treatment at 520 ℃ for different times were studied.The results show that the solidification microstructure exhibit coarse dendrite structure and a lot of second phases exist in the dendrite regions or on the grain boundaries.Quite a number of GdMg3 phases formed during non-equilibrium solidification,cannot be eliminated by solution heat treatment.The grain size changes abnormally during solution treatments at 520 ℃ for different times.After solution treatment at 520 ℃ for 14 h,the average grain size of the alloy decreases to only 1/3 of that of as cast.However,farther prolongation of the solution time results in increase of the grain size.Therefore,grain refining of the studied alloy can be achieved by controlling the solution temperature and time.更多还原