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<p>Hypereutectic Al–Si alloys produced from recycled feedstocks often show unstable microstructure and mechanical performance because hard-to-control impurities can reduce modifier efficiency. Al-22Si alloys prepared from recycled and commercially pure aluminum were processed by a combined serpentine pouring channel (SPC) and Sr-modification process, followed by high-pressure die casting (HPDC). The SPC treatment dominated primary Si refinement in both alloys, reducing the average size from about 75 μm to below 30 μm. In contrast, eutectic modification differed markedly. The commercially pure alloy exhibited a complete modification of eutectic Si from plate-like to fibrous when Sr was at or above 0.09 wt%, whereas the recycled alloy remained largely unmodified even at 0.12 wt%. Chemical analysis showed much lower Sr retention in the recycled alloy, consistent with impurity-related consumption of active Sr and the formation of stable Sr-containing compounds. Consequently, the commercially pure alloy reached a maximum tensile strength of 255 MPa at 0.12 wt% Sr, while the recycled alloy stayed near 200 MPa. The results highlight the need for impurity control and Sr compensation to achieve reliable modification in recycled hypereutectic Al–Si castings.</p>

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Effect of Serpentine Pouring Channel Combined Sr Treatment on Microstructure and Properties of Al–Si Alloys Prepared from Recycled or Commercially Pure Aluminum

  • 期刊论文

  • 发表日期：

    2026年3月5日

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  • Lizhen Liu,
  • Pengyu Yan,
  • Kai Lv,
  • Huimin Liu,
  • Min Ao

摘要

Hypereutectic Al–Si alloys produced from recycled feedstocks often show unstable microstructure and mechanical performance because hard-to-control impurities can reduce modifier efficiency. Al-22Si alloys prepared from recycled and commercially pure aluminum were processed by a combined serpentine pouring channel (SPC) and Sr-modification process, followed by high-pressure die casting (HPDC). The SPC treatment dominated primary Si refinement in both alloys, reducing the average size from about 75 μm to below 30 μm. In contrast, eutectic modification differed markedly. The commercially pure alloy exhibited a complete modification of eutectic Si from plate-like to fibrous when Sr was at or above 0.09 wt%, whereas the recycled alloy remained largely unmodified even at 0.12 wt%. Chemical analysis showed much lower Sr retention in the recycled alloy, consistent with impurity-related consumption of active Sr and the formation of stable Sr-containing compounds. Consequently, the commercially pure alloy reached a maximum tensile strength of 255 MPa at 0.12 wt% Sr, while the recycled alloy stayed near 200 MPa. The results highlight the need for impurity control and Sr compensation to achieve reliable modification in recycled hypereutectic Al–Si castings.