Regulation of Fe-rich Phases in Fine-grained Al-7Si-0.35Mg-0.15Fe Alloys
0.5％Al-TCB was added to obtain fine-grained Al-7Si-0.35Mg-0.15Fe alloy,and Mn and Cr were intro-duced to modulate Fe-rich phase.The modulation effects and intrinsic reasons were comparatively analyzed.The results reveal that both Mn and Cr modify the Fe-rich phase by replacing Fe in the β-AlFeSi phase,leading to the transformation of flaky Fe-rich phase to fishbone α-Al(Fe,Mn)Si phase and massive α-Al(Fe,Cr)Si phase,and the latter is finer and more uniformly distributed in the alloy.The tensile strength,yield strength and elongation of the alloy with 0.1％Mn(mass fraction)addition can reach up to(327±9)MPa、(255±7)MPa and 10.0％±0.8％,respec-tively,which are higher than that of ones with 0.2％Mn.When 0.1％Cr is introduced,the tensile strength,yield strength and elongation reach(335±9)MPa、(270±6)MPa and 11.4％±0.7％,respectively,which are also higher than that of ones with 0.2％Cr addition,indicating that Cr exhibits a stronger plasticizing effect on the alloy than Mn under identical contents.The work is of great significance for the green and renewable utilization of fine-grained A356 aluminum alloy(Fe≥0.15％).
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