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<p>Improved precipitation characteristics of dispersoids are critical for suppressing recrystallization in aluminum alloys. This study reveals an unexpected yet significant role of Cu addition in modifying the dispersoid characteristics in Al–Mg–Si–Mn–Cr alloys. The results indicate that Cu addition improves the uniformity and number density of <i>α</i>-dispersoids while simultaneously reducing their average size. These dispersoids exhibit distinctive morphologies with structural variations, including regular simple cubic and intermediate quasicrystal structures. Notably, Cu addition improves the thermal stability of dispersoids, leading to a higher proportion of quasicrystal dispersoids retained in Cu-modified alloy. In response to that, optimized deformed microstructure and resultant synergistic improvement in strength and ductility were achieved in the Cu-modified alloy. The enhanced dispersoid precipitation is primarily attributed to the formation of dense <i>Q</i>′-AlMgSiCu precipitates during early stages of treatment, serving as nucleation sites for the dispersoid precipitation. HAADF-STEM and APT analyses confirm Cu segregation at the dispersoid/Al interface, which is proposed to lower the interfacial energy and thereby stabilize the dispersoids. Density functional theory calculations further support these findings, indicating that Cu segregation lowers the interfacial energy, promoting the stability of dispersoids during homogenization.</p>

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Enhanced Precipitation Characteristics and Thermal Stability of α-Dispersoids in Al–Mg–Si–Mn–Cr Alloys with Cu Addition

  • 期刊论文

  • 发表日期：

    2025年8月6日

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  • Fangzhen Liu,
  • Qipeng Dong,
  • Ziwei Yao,
  • Jian Qin,
  • Zhen Li,
  • Bo Zhang,
  • Hiromi Nagaumi

摘要

Improved precipitation characteristics of dispersoids are critical for suppressing recrystallization in aluminum alloys. This study reveals an unexpected yet significant role of Cu addition in modifying the dispersoid characteristics in Al–Mg–Si–Mn–Cr alloys. The results indicate that Cu addition improves the uniformity and number density of α-dispersoids while simultaneously reducing their average size. These dispersoids exhibit distinctive morphologies with structural variations, including regular simple cubic and intermediate quasicrystal structures. Notably, Cu addition improves the thermal stability of dispersoids, leading to a higher proportion of quasicrystal dispersoids retained in Cu-modified alloy. In response to that, optimized deformed microstructure and resultant synergistic improvement in strength and ductility were achieved in the Cu-modified alloy. The enhanced dispersoid precipitation is primarily attributed to the formation of dense Q′-AlMgSiCu precipitates during early stages of treatment, serving as nucleation sites for the dispersoid precipitation. HAADF-STEM and APT analyses confirm Cu segregation at the dispersoid/Al interface, which is proposed to lower the interfacial energy and thereby stabilize the dispersoids. Density functional theory calculations further support these findings, indicating that Cu segregation lowers the interfacial energy, promoting the stability of dispersoids during homogenization.