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<p>The present study investigates the effects of laser resolidification on AlSi10Mg alloys modified with Nickel (Ni), describing the evolution of microstructure and nanohardness due to rapid solidification and growth of AlNi intermetallic phases. The AlSi10Mg alloy has an excellent strength-to-weight ratio and is widely used in automotive and aerospace parts. Adding Ni helps increase its hardness and improve performance. Further, rapid solidification <i>via</i> laser surface remelting (LSR) promotes microstructural refinement and strengthening. Thus, LSR treatment was applied to AlSi10Mg with 1 to 3 wt pct Ni using two different energy densities: 100 and 400&#xa0;J/mm<sup>2</sup>. Microstructural evolution was quantified using optical microscopy, scanning electron microscopy, and image analysis, then correlated to models generated using Computer Coupling of Phase Diagrams and Thermochemistry (CALPHAD). The phase clusters identified in the molten pools included <i>α</i>-Al, Al + Si and Al + Si + Al<sub>3</sub>Ni constituents. Rapid solidification led to the formation of <i>α</i>-Al cells at the top and very fine eutectic Si fibers, while Al<sub>3</sub>Ni formed complex fishbone-like structures. Measurements of secondary dendritic spacing agreed well with theoretical (Bouchard–Kirkaldy) predictions. However, the equilibrium and Scheil models did not match the experimental phase fractions. The reasonable to good agreement with the Bouchard–Kirkaldy (BK) predictions supported its applicability, despite limitations related to the thermal gradient. Such predictions demonstrated positive correlations with depth in the melt pool (<i>i.e.</i>, top to bottom) and with increasing solidification velocity. Nanoindentation measurements of hardness were taken with high spatial resolution, showing that local hardness increased with Ni content, correlating with the Al<sub>3</sub>Ni fraction and the refinement of Si particles. These results support the effectiveness of Ni alloying and LSR to improve the performance of castable aluminum alloys and guide the selection of parameters to maximize hardness.</p>

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Laser Resolidification of AlSi10Mg Alloys Modified with Ni: Microstructural Evolution and Mechanical Properties by Nanoindentation

  • 期刊论文

  • 发表日期：

    2025年12月3日

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  • Danusa Araújo de Moura,
  • José Eduardo Spinelli,
  • Daniel Sinclair,
  • Ankit Kumar,
  • Nikhilesh Chawla

摘要

The present study investigates the effects of laser resolidification on AlSi10Mg alloys modified with Nickel (Ni), describing the evolution of microstructure and nanohardness due to rapid solidification and growth of AlNi intermetallic phases. The AlSi10Mg alloy has an excellent strength-to-weight ratio and is widely used in automotive and aerospace parts. Adding Ni helps increase its hardness and improve performance. Further, rapid solidification via laser surface remelting (LSR) promotes microstructural refinement and strengthening. Thus, LSR treatment was applied to AlSi10Mg with 1 to 3 wt pct Ni using two different energy densities: 100 and 400 J/mm2. Microstructural evolution was quantified using optical microscopy, scanning electron microscopy, and image analysis, then correlated to models generated using Computer Coupling of Phase Diagrams and Thermochemistry (CALPHAD). The phase clusters identified in the molten pools included α-Al, Al + Si and Al + Si + Al3Ni constituents. Rapid solidification led to the formation of α-Al cells at the top and very fine eutectic Si fibers, while Al3Ni formed complex fishbone-like structures. Measurements of secondary dendritic spacing agreed well with theoretical (Bouchard–Kirkaldy) predictions. However, the equilibrium and Scheil models did not match the experimental phase fractions. The reasonable to good agreement with the Bouchard–Kirkaldy (BK) predictions supported its applicability, despite limitations related to the thermal gradient. Such predictions demonstrated positive correlations with depth in the melt pool (i.e., top to bottom) and with increasing solidification velocity. Nanoindentation measurements of hardness were taken with high spatial resolution, showing that local hardness increased with Ni content, correlating with the Al3Ni fraction and the refinement of Si particles. These results support the effectiveness of Ni alloying and LSR to improve the performance of castable aluminum alloys and guide the selection of parameters to maximize hardness.