Thixotropic behavior and structure evolution of A356 alloy in the semisolid state
Thixotropic behavior and structure evolution of A356 alloy in the semisolid state
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DOI：
10.1016/0956-716x(94)90305-0
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发表时间：
1994-06
期刊：
影响因子：
--
通讯作者：
Y. Yang;C. Tsao
中科院分区：
文献类型：
--
作者：
Y. Yang;C. Tsao
1971年，麻省理工学院的大卫·斯宾塞开创了半固态金属行为的研究。他对凝固的Sn-15 pct Pb合金施加剪切应变，发现与凝固过程中未受到剪切的合金相比，剪切应力显着降低。与未剪切合金的枝晶结构相反，剪切合金的晶粒结构为非枝晶。自从这项早期工作以来，半固态加工（SSP）已成为一种广泛研究和接受的工艺。与普通铸造材料相比，SSP材料的偏析少，晶粒细小。在实际生产中，过磷酸钙具有提高零件成形率、减少模具热冲击、延长模具寿命等优点。A356铝硅合金具有铸造性能好、力学性能好、重量轻、抗氧化性好等特点，应用广泛。该合金的固相线和液相线温度分别为830 K和886 K，为研究半固态行为提供了较宽的半固态区。研究了A356合金半固态成形过程中非枝晶组织的演变及触变行为。在此过程中，采用机械搅拌技术制备半固态浆料。
The study on the behavior of metals in the semisolid state was pioneered by David Spencer at MIT in 1971. He applied a shear strain on solidifying Sn-15 pct Pb alloy, and discovered a remarkable reduction in shear stress comparing with those that were not sheared during solidification. The grain structure of the sheared alloy was nondendritic, as opposed to the dendritic structure of not-sheared alloy. Since this early work, semisolid processing (SSP) has become a widely studied and accepted process. Comparing with conventional cast materials, SSP materials have less segregation and finer grain size. Practically, SSP can increase part-forming rate, reduce the thermal shock imposed on the mold, increase mold life, etc. A356 Al-Si alloy has the following characteristics, i.e. good castability and mechanical properties, light weight and a better oxidation resistance, and is widely used. The solidus and liquidus of the alloy are 830 K and 886 K, respectively, which provide a considerably wide semisolid regime that is suitable for the studies on the semisolid behaviors. The evolution of nondendritic structure and the thixotropic behavior of A356 alloy during semisolid processing were studied. During the process, semisolid slurry was produced using mechanical stirring technique.