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Effect of Ca modification on the elemental composition, microstructure and tensile properties of Al-7Si-0.3Mg alloy

  • Jia-hong Zhang
  • Shu-ming XingEmail author
  • Xiao-hui Ao
  • Peng Sun
  • Ru-fen Wang
Article
  • 34 Downloads

Abstract

The effect of Ca addition on the elemental composition, microstructure, Brinell hardness and tensile properties of Al-7Si-0.3Mg alloy were investigated. The residual content of Ca in the alloy linearly increased with the amount of Ca added to the melt. The optimal microstructure and properties were obtained by adding 0.06wt% Ca to Al-7Si-0.3Mg alloy. The secondary dendrite arm spacing (SDAS) of the primary α phase decreased from 44.41 μm to 19.4 μm, and the eutectic Si changed from coarse plates to fine coral. The length of the Fe-rich phase (β-Al5FeSi) decreased from 30.2 μm to 3.8 um, and the Brinell hardness can reach to 66.9. The ultimate tensile strength, yield strength, and elongation of the resulting alloy increased from 159.5 MPa, 79 MPa, and 2.5% to 212 MPa, 86.5 MPa, and 4.5%, respectively. The addition of Ca can effectively refine the primary α phase and modify the eutectic Si phase, likely because Ca enrichment at the front of the solid-liquid interface led to undercooling of the alloy, reduced the growth rate of the primary α phase, and refined the grain size. Also, it could increase the latent heat of crystallization, undercooling, and the nucleation rate of eutectic Si, which was beneficial to the improvement of the morphology of eutectic Si.

Keywords

Ca Al-Si-Mg alloy microstructure mechanical properties 

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Notes

Acknowledgments

This research was financially supported by the National High-tech R&D Program of China (No. 2014AA041804) and International S&T Cooperation Program of China (No. 2014DFA53050).

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Copyright information

© University of Science and Technology Beijing and Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Jia-hong Zhang
    • 1
  • Shu-ming Xing
    • 1
    Email author
  • Xiao-hui Ao
    • 1
  • Peng Sun
    • 2
  • Ru-fen Wang
    • 2
  1. 1.School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijingChina
  2. 2.Tianjin Lizhong Alloy Group Company LimitedTianjinChina

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