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<p>To improve the mechanical properties of Al-Si cast alloy and develop a novel rare-earth-based grain refiner and modifier, the effects of Sr and varying Ce contents (0, 0.05, 0.1, 0.2, and 0.3 wt.%) on the microstructure and mechanical properties of A356 alloy were systematically investigated. Ce was introduced in the form of an Al-12Ce master alloy, consisting of <i>α</i>-Al and Al<sub>11</sub>Ce<sub>3</sub> phases. The addition of Sr alone can modify the eutectic Si, but has a limited effect on the coarse <i>α</i>-Al dendrites. With the addition of 0.1 wt.% Ce, the alloy grain size was significantly refined, and the eutectic Si was further modified. Mechanical property tests reveal that the alloy containing 0.1 wt.% Ce achieves the optimal combination of microstructure and tensile performance. Additionally, it was found that the Fe-phase morphology of the alloys was favorably altered by the addition of Ce. On the one hand, Al<sub>11</sub>Ce<sub>3</sub> shares the same crystallographic orientation with <i>α</i>-Al, and its relatively small lattice mismatch allows it to act as an effective heterogeneous nucleation site. On the other hand, Ce addition induces constitutional undercooling, shortening the local solidification time of the dendrites. As a result, the <i>α</i>-Al grains are refined. The modification of the eutectic Si by Ce is attributed to the aggregation of Ce atoms at the solid/liquid interface of Si, which hinders the diffusion of Si atoms and suppresses their stepwise growth, thereby refining the size of the eutectic Si.</p>

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Achieving Grain Refinement and Eutectic Si Modification in A356 Alloy through Ce Addition

  • 期刊论文

  • 发表日期：

    2026年1月23日

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  • Boyu Yang,
  • Lingtao Meng,
  • Li Wang,
  • Mingxu Wang,
  • Dan Liu,
  • Junpeng Duan,
  • Jun Shi,
  • Ning Mao,
  • Hongbo Yang,
  • Dunbo Yu,
  • Mengrui Li,
  • Guibing Shi

摘要

To improve the mechanical properties of Al-Si cast alloy and develop a novel rare-earth-based grain refiner and modifier, the effects of Sr and varying Ce contents (0, 0.05, 0.1, 0.2, and 0.3 wt.%) on the microstructure and mechanical properties of A356 alloy were systematically investigated. Ce was introduced in the form of an Al-12Ce master alloy, consisting of α-Al and Al11Ce3 phases. The addition of Sr alone can modify the eutectic Si, but has a limited effect on the coarse α-Al dendrites. With the addition of 0.1 wt.% Ce, the alloy grain size was significantly refined, and the eutectic Si was further modified. Mechanical property tests reveal that the alloy containing 0.1 wt.% Ce achieves the optimal combination of microstructure and tensile performance. Additionally, it was found that the Fe-phase morphology of the alloys was favorably altered by the addition of Ce. On the one hand, Al11Ce3 shares the same crystallographic orientation with α-Al, and its relatively small lattice mismatch allows it to act as an effective heterogeneous nucleation site. On the other hand, Ce addition induces constitutional undercooling, shortening the local solidification time of the dendrites. As a result, the α-Al grains are refined. The modification of the eutectic Si by Ce is attributed to the aggregation of Ce atoms at the solid/liquid interface of Si, which hinders the diffusion of Si atoms and suppresses their stepwise growth, thereby refining the size of the eutectic Si.