Influences of Fe, Mn and Y additions on microstructure and mechanical properties of hypoeutectic Al–7%Si alloy

• Published in: Intermetallics Vol. 120; p. 106768
• Main Authors: Li, Qinglin, Zhu, Yuqian, Zhao, Shang, Lan, Yefeng, Liu, Dexue, Jian, Guangfei, Zhang, Qiang, Zhou, Hongwei
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.05.2020; Elsevier BV
• Subjects: Aluminum base alloys; Al–20%Si-2.5%Fe–2%Mn master alloy; Dendritic structure; Ductile fracture; Ductile-brittle transition; Elongation; Grain size; Heat treating; Hypoeutectic Al–7%Si alloy; Intermetallics; Iron; Manganese; Master alloys; Mechanical properties; Microstructure; Rare earth Y; Silicon base alloys; Tensile tests; Ultimate tensile strength; Yttrium; Mechanical properties; Intermetallics; Al–20%Si-2.5%Fe–2%Mn master alloy; Microstructure; Rare earth Y; Hypoeutectic Al–7%Si alloy
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2020.106768

In this work, the influences of Fe, Mn and Y with various contents on microstructural evolution and mechanical properties of hypoeutectic Al–7%Si alloy were investigated by microscopy technology and tensile test. The results showed that the complex addition of Al–20%Si-2.5%Fe–2%Mn master alloy and rare earth Y have much better refining effect of need-like eutectic Si and coarse α-Al dendrites than that of separate addition of master alloy or rare earth Y. Combined additions of 7.0% master alloy and 0.2% Y, the average grain size was decreased by 89.5% from 483.1 μm to 50.8 μm and secondary dendrite arm spacing (SDAS) was reduced by 46.8% from 26.9 μm to 14.3 μm. Moreover, the coarse flake-like eutectic Si structure was effectively modified into fine fiber and granular shape. In addition, ultimate tensile strength (UTS) was improved by 33.3% from 162 MPa to 216 MPa, and elongation (El) value was enhanced by 46.7% from 6.2% to 9.1%. The fracture mode transformed from brittle fracture to ductile fracture. •A novel complex inoculant of Al–20Si-2.5Fe–2Mn and Y has been developed to modify α-Al and eutectic Si of Al–7%Si alloy.•The modifying effect of α-Al and eutectic Si is the best after the combined addition of 7% master alloy and 0.2% Y.•The UTS was enhanced by 33.3% from 162 MPa to 216 MPa, and the El was increased by 46.7% from 6.2% to 9.1%.