Effects of T6 heat treatment on the microstructure, tensile properties, and fracture behavior of the modified A356 alloys
Effects of T6 heat treatment on the microstructure, tensile properties, and fracture behavior of the modified A356 alloys
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T6热处理对变质A356合金显微组织、拉伸性能和断裂行为的影响
DOI：
10.1016/j.matdes.2011.11.018
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发表时间：
2012-04
期刊：
影响因子：
--
通讯作者：
坚增运
中科院分区：
文献类型：
--
作者：
坚增运
众所周知，热处理会引起共晶硅的球化。研究了T6热处理对La和Ce复合稀土改性A356合金组织、拉伸性能和断裂行为的影响。显微组织分析表明，改性后的A356合金的共晶硅颗粒尺寸大大减小，Si颗粒的精孢化程度显著提高。结果表明，改性前后共晶硅颗粒的平均直径、圆度和纵横比分别降低了48.10 ~ 56.85%、49.55 ~ 54.52%和13.36 ~ 30.17%。改性后的A356合金的拉伸性能得到了提高，特别是塑性得到了提高。这可能与二次枝晶臂间距减小、细共晶硅球化和析出硬化有关。扫描电镜（SEM）分析表明，变质合金中存在一对细小且分布均匀的韧窝，是韧性断裂的主要原因。共晶硅颗粒和含re的金属间化合物是断裂过程中的薄弱环节。
It is known that heat treatment causes the spheroidization of eutectic silicon. This paper presents the influence of T6 heat treatment on the microstructures, tensile properties, and fracture behavior of the A356 alloys modified by mischmetal containing La and Ce elements. Microstructural analysis showed that the size of eutectic silicon particles was greatly reduced and the extent of speroidisation of Si particles was remarkably improved for the modified A356 alloys. Comparison between the unmodified and modified alloys suggested that the values of mean diameter, roundness, and aspect ration of eutectic silicon particles were decreased by 48.10–56.85%, 49.55–54.52%, and 13.36–30.17%, respectively. The tensile properties of the modified A356 alloys can be enhanced, especially the ductility. These could be associated with the decrease of secondary dendrite arm spacing, spheroidization of fine eutectic silicon and precipitation hardening. Scanning electron microscopy (SEM) examination indicated that the ductile fracture mechanism was responsible for the modified alloys due to the existence of a couple of fine and uniformly distributed dimples. And the eutectic silicon particles and RE-containing intermetallic compounds provide the weak locations during the fracture process.
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DOI：
10.1007/s11661-999-0301-8
发表时间：
1999-10-01
影响因子：
2.8
作者：
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DOI：
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1980
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影响因子：
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