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<p>Adding graphene nanoplatelets (GNPs) to the magnesium matrix for the preparation of magnesium matrix composites (MMCs) can effectively enhance their strength and modulus. However, a notable trade-off between strength and toughness severely limits their industrial applications. In this study, a bimodal structure in GNPs/Mg-8Al-1Sm composites was constructed by optimizing the interface between graphene and the magnesium matrix, and the effects of extrusion temperatures (300, 350, and 400&#xa0;°C) on the composites' microstructure, recrystallization, texture, and mechanical properties were investigated. Research has found that, when the composites extruded at 300&#xa0;°C, the composites exhibited a yield strength (YS) of 286&#xa0;MPa, an ultimate tensile strength (UTS) of 334&#xa0;MPa, and an elongation (EL) of 9.8%. As the extrusion temperature increased to 350 and 400&#xa0;°C, their YS, UTS, and EL decreased, however, their EL (7.1%) and 400&#xa0;°C (7.5%) did not show significant differences. Elevated temperatures enhanced GNP dispersion, resulting in improved plasticity and recrystallization, which increased from 67 to 83%, leading to larger grains and a higher fraction of coarse grains (CG). GNPs, concentrated at grain boundaries, influenced recrystallization by promoting dynamic nucleation and pinning grain boundaries, resulting in a bimodal grain structure comprising fine grains (FG) and CG zones. The FG zone exhibited higher dislocation densities and a weaker basal texture, while the CG zone demonstrated stronger texture, contributing to the composite's strength and work-hardening ability. This structure fully utilizes the coordinated deformation capacities of CG, FG, and graphene, resulting in a synergistic enhancement of both strength and ductility in MMCs.</p> Graphical abstract <p></p>

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Preparation of a bimodal grain-structured 0.4GNPs/Mg-8Al-1Sm composites via adjusting the extrusion temperature

  • 期刊论文

  • 发表日期：

    2025年1月16日

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  • Zehua Yan,
  • Yandong Yu,
  • Wei Zhang,
  • Hao Zhou

摘要

Adding graphene nanoplatelets (GNPs) to the magnesium matrix for the preparation of magnesium matrix composites (MMCs) can effectively enhance their strength and modulus. However, a notable trade-off between strength and toughness severely limits their industrial applications. In this study, a bimodal structure in GNPs/Mg-8Al-1Sm composites was constructed by optimizing the interface between graphene and the magnesium matrix, and the effects of extrusion temperatures (300, 350, and 400 °C) on the composites' microstructure, recrystallization, texture, and mechanical properties were investigated. Research has found that, when the composites extruded at 300 °C, the composites exhibited a yield strength (YS) of 286 MPa, an ultimate tensile strength (UTS) of 334 MPa, and an elongation (EL) of 9.8%. As the extrusion temperature increased to 350 and 400 °C, their YS, UTS, and EL decreased, however, their EL (7.1%) and 400 °C (7.5%) did not show significant differences. Elevated temperatures enhanced GNP dispersion, resulting in improved plasticity and recrystallization, which increased from 67 to 83%, leading to larger grains and a higher fraction of coarse grains (CG). GNPs, concentrated at grain boundaries, influenced recrystallization by promoting dynamic nucleation and pinning grain boundaries, resulting in a bimodal grain structure comprising fine grains (FG) and CG zones. The FG zone exhibited higher dislocation densities and a weaker basal texture, while the CG zone demonstrated stronger texture, contributing to the composite's strength and work-hardening ability. This structure fully utilizes the coordinated deformation capacities of CG, FG, and graphene, resulting in a synergistic enhancement of both strength and ductility in MMCs.

Graphical abstract