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对汽车发动机用Mg-7Gd-5Y合金进行了固溶和时效处理,研究了固溶温度和时效时间对合金微观组织与力学性能的影响,并分析了其作用机理。结果表明:铸态合金中主要由α-Mg固溶体、Mg3(Gd,Y)相、14H长周期相和立方状富稀土相组成;在固溶温度为500℃时,合金的抗拉强度相对原始态提高了11%、断后伸长率提高了2.4%,具有较好的强度和塑性结合;随着固溶温度的升高,晶界处共晶相含量逐渐减小;500℃固溶10 h后晶界向晶内生长的长周期相片层变薄,并形成了较多的堆垛层错;随着时效时间的延长,合金的屈服强度和抗拉强度都表现为先升高而后降低的趋势,在时效时间为120 h时达到最大值,而断后伸长率随着时效时间的延长而整体保持逐渐降低的趋势。
The microstructure and mechanical properties of Mg-7Gd-5Y alloy for automotive engine were studied by solution treatment and aging treatment. The effects of solution temperature and aging time on the microstructure and mechanical properties of the alloy were studied. The mechanism of action was also analyzed. The results show that the as-cast alloys mainly consist of α-Mg solid solution, Mg3 (Gd, Y) phase, 14H long period phase and cubic rare earth-rich phase. When the solution temperature is 500 ℃, State increased by 11%, the elongation after fracture increased by 2.4%, with good strength and plasticity; with the solution temperature increases, the grain boundary eutectic phase content gradually decreased; 500 ℃ solution 10 h After the grain boundary grows into the growth of the long-period phase thinning layer, and the formation of more stacking faults; with the aging time, the alloy yield strength and tensile strength showed the first increase and then decreased The trend reached the maximum at the aging time of 120 h, while the elongation at break decreased gradually as the aging time prolonged.