The characterization of Fe-rich phases in a high-pressure die cast hypoeutectic aluminum-silicon alloy
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2020年第16期
论文作者：X.Y.Jiao C.F.Liu Z.P.Guo G.D.Tong S.L.Ma Y.Bi Y.F.Zhang S.M.Xiong
文章页码：54 - 62
摘 要：Both microstructural characteristics and fracture behavior of Fe-rich phases in a high-pressure die-cast hypoeutectic Al-Si alloy were investigated. Attention was focused on the morphology and formation mechanism of Fe-rich phases, together with their influence on fracture. Results show that primary Ferich phases exhibited in blocky shape precipitated from liquid while secondary Fe-rich phase in a large net shape was distributed along eutectic boundary participating in a ternary eutectic reaction. Through synchrotron X-ray tomography characterization, three Fe-rich phases with different morphologies, i.e.,polyhedral shape, fine compact shape and Chinese script-type shape were extracted along the radial direction. Lower slow-shot speed promoted the polyhedral Fe-rich phase to precipitate in slow-shot sleeve while decreased the formation of fine compact and Chinese script-type Fe-rich phases in die cavity. Because of a worse deformation compatibility, polyhedral Fe-rich phases fractured and became stress concentration sources before the failure of the casting.
X.Y.Jiao1，C.F.Liu1，Z.P.Guo1,2，G.D.Tong3，S.L.Ma3，Y.Bi3，Y.F.Zhang3，S.M.Xiong1,2
1. School of Materials Science and Engineering, Tsinghua University2. Key Laboratory for Advanced Materials Processing Technology, Tsinghua University3. China FAW Foundary Co., LTD
摘 要：Both microstructural characteristics and fracture behavior of Fe-rich phases in a high-pressure die-cast hypoeutectic Al-Si alloy were investigated. Attention was focused on the morphology and formation mechanism of Fe-rich phases, together with their influence on fracture. Results show that primary Ferich phases exhibited in blocky shape precipitated from liquid while secondary Fe-rich phase in a large net shape was distributed along eutectic boundary participating in a ternary eutectic reaction. Through synchrotron X-ray tomography characterization, three Fe-rich phases with different morphologies, i.e.,polyhedral shape, fine compact shape and Chinese script-type shape were extracted along the radial direction. Lower slow-shot speed promoted the polyhedral Fe-rich phase to precipitate in slow-shot sleeve while decreased the formation of fine compact and Chinese script-type Fe-rich phases in die cavity. Because of a worse deformation compatibility, polyhedral Fe-rich phases fractured and became stress concentration sources before the failure of the casting.
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