首页|Improvement of impact properties of Al-Si-Mg alloy via solution treatment and joint modification with Sr and La
Improvement of impact properties of Al-Si-Mg alloy via solution treatment and joint modification with Sr and La
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An effort to obtain superior impact properties for Al-7Si-0.35 Mg alloy is presented,where modification with 0.02 wt%Sr and 0.1 wt%La as well as solution treatment was jointly employed.The samples were solution treated at 535 ℃ for 15 min to 12 h.The microstructure,fracture mecha-nism,and their correlation with the impact properties of the alloy were studied in detail mainly through optical micro-scopy(OM),scanning electron microscopy(SEM)and oscillography impact test.The results show that the addition of Sr and La refined the eutectic Si particles significantly from~2.05 pm(modified with Sr alone)to~0.75 pm in as-cast microstructure,leading to a very homogeneous dis-tribution of spheroidized Si particles in the alloy solution treated at 535 ℃ for 8 h.The alloy exhibits excellent impact toughness up to 75 J·cm-2,which is much higher than the maximum impact toughness of the alloys modified by Sr alone(~46 J·cm-2).The major reason for this remarkable increase in the impact property is the dramatic increase in crack initiation energy.The dispersoid-free zones(DFZs)near the eutectic regions mainly consist of the ductile Al-matrix,which exhibits excellent ductility.The ductile Al-matrix of the DFZs hinders the crack propagation,resulting in a significant increase in crack propagation energy.
Xiong-Ling Zheng、Shao-Xiang Li、Jia-Le Ma、Qing-Yan Xu、Hai-Dong Zhao、Zhi-Qiang Han
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Key Laboratory for Advanced Materials Processing Technology,Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China
National Engineering Research Center of Near-Net Shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510641,China