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以A356合金为研究对象,采用扫描电镜、投射电镜、硬度测试仪及拉伸试验机,研究了其在170℃时效温度下不同时效时间处理对合金组织及力学性能的影响规律。结果表明,时效6 h时,合金中析出相的数量和尺寸均达到极值,其强度和硬度也达到峰值,伸长率降至4.2%左右;增加时效时间,合金各性能增长不明显,因此170℃时最优时效时间为6 h;拉伸断口形貌为韧性断裂,说明经时效的A356合金具有一定塑性,但其塑性会随着时效时间的延长而降低。
Using A356 alloy as the research object, the effects of different aging treatments at 170 ℃ aging temperature on the microstructure and mechanical properties of the alloy were studied by SEM, TEM, hardness tester and tensile tester. The results show that when the aging time is 6 h, the number and size of the precipitates in the alloy reach the extreme value, and their strength and hardness reach the peak value, the elongation rate drops to about 4.2%. When the aging time is increased, the growth performance of the alloy is not obvious The optimal aging time at 170 ℃ is 6 h. Tensile fracture morphology is ductile fracture, which indicates that aged A356 alloy has some plasticity but its plasticity decreases with the aging time.