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<p>This study investigates the microstructural evolution and nanomechanical response of additively manufactured AlSi10Mg alloy following T4 (solution treatment + natural ageing) and T6 (solution treatment + artificial ageing) heat treatments. Specimens were fabricated via selective laser melting (SLM) and then characterized using electron backscatter diffraction (EBSD), digital image correlation (DIC), nanoindentation, and surface profilometry. EBSD analysis reveals that solution treatment induces dynamic recrystallization, markedly reducing grain orientation spread (GOS) from 0.58° (as-printed) to &lt; 0.25° (heat-treated), signifying substantial mitigation of SLM-induced residual stresses. Grain refinement follows the trend: as-printed (4.18&#xa0;μm) &gt; T4 (3.13&#xa0;μm) &gt; T6 (2.66&#xa0;μm), consistent with Hall–Petch strengthening (d⁻⁰·⁵). T6 treatment promotes pronounced spheroidization and dissolution of the eutectic Si (silicon) network, precipitate hardening via Mg₂Si formation, and pore coalescence, resulting in superior microstructural homogeneity and ~ 18% lower porosity versus T4. DIC-monitored tensile tests demonstrate a transition from brittle fracture (as-printed, necking absent) to ductile failure with stable necking in heat-treated conditions; T6 exhibits a slightly lower post-necking strain capacity (εₙ = 0.129) compared to T4 (εₙ = 0.131), but demonstrates a higher ultimate tensile strength, indicating a favourable strength–ductility balance. Nanoindentation results reveal a reduction in nanohardness after heat treatment, attributed to dissolution of the as-built eutectic Si network, residual stress relief, precipitate shearing, and improvements in elastic recovery and strain tolerance. The decrease in surface roughness (Ra) from 6.65&#xa0;μm (as-printed) to 5.29&#xa0;μm (T6) is attributed to spheroidization of eutectic Si, resulting in a more uniform, less irregular surface morphology. Collectively, these results establish T6 as the optimal post-processing route for enhancing the structural integrity and mechanical reliability of SLM AlSi10Mg components in load-bearing applications.</p>

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Microstructural evolution and nanomechanical behaviour of additively manufactured AlSi10Mg under T4 and T6 heat treatments: a multiscale EBSD-DIC approach

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月2日

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  • Samuel Olukayode Akinwamide,
  • Waqas Ahmad,
  • Sven Bossuyt,
  • Ojo Jeremiah Akinribide,
  • Pedro Vilaca

摘要

This study investigates the microstructural evolution and nanomechanical response of additively manufactured AlSi10Mg alloy following T4 (solution treatment + natural ageing) and T6 (solution treatment + artificial ageing) heat treatments. Specimens were fabricated via selective laser melting (SLM) and then characterized using electron backscatter diffraction (EBSD), digital image correlation (DIC), nanoindentation, and surface profilometry. EBSD analysis reveals that solution treatment induces dynamic recrystallization, markedly reducing grain orientation spread (GOS) from 0.58° (as-printed) to < 0.25° (heat-treated), signifying substantial mitigation of SLM-induced residual stresses. Grain refinement follows the trend: as-printed (4.18 μm) > T4 (3.13 μm) > T6 (2.66 μm), consistent with Hall–Petch strengthening (d⁻⁰·⁵). T6 treatment promotes pronounced spheroidization and dissolution of the eutectic Si (silicon) network, precipitate hardening via Mg₂Si formation, and pore coalescence, resulting in superior microstructural homogeneity and ~ 18% lower porosity versus T4. DIC-monitored tensile tests demonstrate a transition from brittle fracture (as-printed, necking absent) to ductile failure with stable necking in heat-treated conditions; T6 exhibits a slightly lower post-necking strain capacity (εₙ = 0.129) compared to T4 (εₙ = 0.131), but demonstrates a higher ultimate tensile strength, indicating a favourable strength–ductility balance. Nanoindentation results reveal a reduction in nanohardness after heat treatment, attributed to dissolution of the as-built eutectic Si network, residual stress relief, precipitate shearing, and improvements in elastic recovery and strain tolerance. The decrease in surface roughness (Ra) from 6.65 μm (as-printed) to 5.29 μm (T6) is attributed to spheroidization of eutectic Si, resulting in a more uniform, less irregular surface morphology. Collectively, these results establish T6 as the optimal post-processing route for enhancing the structural integrity and mechanical reliability of SLM AlSi10Mg components in load-bearing applications.