Enhanced strength and ductility of A356 alloy due to composite effect of near-rapid solidification and thermo-mechanical treatment
Enhanced strength and ductility of A356 alloy due to composite effect of near-rapid solidification and thermo-mechanical treatment
复制标题
近快速凝固和热机械处理的复合效应增强了 A356 合金的强度和延展性
DOI：
10.1016/j.msea.2019.03.039
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发表时间：
2019
期刊：
影响因子：
6.4
通讯作者：
Liu F.
中科院分区：
文献类型：
--
作者：
Zhang X.;Huang L. K.;Zhang B.;Chen Y. Z.;Duan S. Y.;Liu G.;Yang C. L.;Liu F.
粗大的枝晶组织和不均匀分布的共晶硅颗粒导致A356合金的塑性较差，从而对通过室温变形提高力学性能提出了挑战。提出了一种将近快速凝固与两步热机械处理(TMT)相结合的新工艺。为了显著改善合金的塑性，采用近快速凝固技术，结合等通道转角挤压(ECAP)和中间热处理等第一步TMT工艺，细化共晶硅颗粒，使其在基体中均匀分布。在此基础上，通过二次时效处理和复合变形(ECAP+深冷变形)，可获得较高的∼483×10-6 Mpa，较好的断裂伸长率∼8.1%。强度和塑性的良好结合主要归功于高密度位错、细小的纳米硅颗粒和均匀分布的共晶硅颗粒的协同作用。本工作为制备高强Al-Si铸造铝合金提供了一种新的思路，从而使Al-Si铸造铝合金的应用前景看好。
The coarse dendritic microstructure with non-uniform distribution of eutectic Si particles leads to poor ductility of A356 alloy, thus challenging the enhancement of mechanical properties through deformation at room temperature. Here, a new processing protocol was proposed by combining near-rapid solidification with two-step thermo-mechanical treatment (TMT). To significantly improve the ductility of the alloy, near-rapid solidification, in combination with first-step TMT including equal channel angular pressing (ECAP) and intermediate heat treatment, was applied to refine eutectic Si particles and make them evenly distributed in the matrix. On this basis, a high ultimate tensile strength ∼483 MPa, with relatively good elongation to failure ∼8.1% can be achieved by the subsequent ageing treatment and composite deformation (ECAP + cryorolling) of second-step TMT. The excellent combination of strength and ductility was mainly attributed to the synergistic effect of high density of dislocations, refined nanoscale Si particles and uniform distributed eutectic Si particles arising from this fabrication processing. This work provides a new idea for the preparation of high strength Al-Si cast aluminum alloy, so that the application of Al-Si cast alloy is promisingly expected to expand.