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<p>Graphene nanoplatelets (GNPs), which are promising reinforcements for Mg-based composites, failed to have their outstanding mechanical properties fully utilized due to the poor dispersibility and weak&#xa0;interfacial bonding between the GNPs and Mg matrix. In this work, GNPs were modified with MgO nanoparticles via a chemical precipitation reaction followed by high-temperature roasting to improve the dispersion in AZ91 alloy and enhance the interfacial bonding. Then, the MgO@GNPs/AZ91 composites were fabricated through a combination of vacuum ball milling and vacuum hot-press sintering process. The microstructure, compactness and mechanical properties of the composites were investigated. The results indicated that MgO nanoparticles uniformly coated on GNPs surface exhibit excellent interface bonding with GNPs, and effectively improve the dispersibility and bonding strength between GNPs and Mg matrix. With increasing the MgO-coated GNPs content, the relative density, hardness and tensile properties of MgO@GNPs/AZ91 composites increase at first and then decrease. The composites with 0.3&#xa0;wt.% MgO-coated GNPs achieve the optimal&#xa0;mechanical properties, with a hardness of 67.9 HV, an ultimate tensile strength of 198&#xa0;MPa, a yield strength&#xa0;of 117&#xa0;MPa and an elongation of 5.3%, increased by 3.6, 39.4, 13.6 and 60.6%, compared to the 0.3GNPs/AZ91 composites, respectively.&#xa0;The improved mechanical properties of the MgO@GNPs/AZ91 composites could be&#xa0;attributed to the dislocation strengthening due to the geometrical mismatch and load transfer strengthening.</p>

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Interface Structure and Strengthening Mechanism of AZ91 Alloy Reinforced by MgO-Coated Graphene Nanoplatelets

  • 期刊论文

  • 发表日期：

    2025年5月12日

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  • Xue Tian,
  • Hongyu Xu,
  • Dihui Song,
  • Bo Jiang,
  • Ye Wang,
  • Maoliang Hu,
  • Zesheng Ji

摘要

Graphene nanoplatelets (GNPs), which are promising reinforcements for Mg-based composites, failed to have their outstanding mechanical properties fully utilized due to the poor dispersibility and weak interfacial bonding between the GNPs and Mg matrix. In this work, GNPs were modified with MgO nanoparticles via a chemical precipitation reaction followed by high-temperature roasting to improve the dispersion in AZ91 alloy and enhance the interfacial bonding. Then, the MgO@GNPs/AZ91 composites were fabricated through a combination of vacuum ball milling and vacuum hot-press sintering process. The microstructure, compactness and mechanical properties of the composites were investigated. The results indicated that MgO nanoparticles uniformly coated on GNPs surface exhibit excellent interface bonding with GNPs, and effectively improve the dispersibility and bonding strength between GNPs and Mg matrix. With increasing the MgO-coated GNPs content, the relative density, hardness and tensile properties of MgO@GNPs/AZ91 composites increase at first and then decrease. The composites with 0.3 wt.% MgO-coated GNPs achieve the optimal mechanical properties, with a hardness of 67.9 HV, an ultimate tensile strength of 198 MPa, a yield strength of 117 MPa and an elongation of 5.3%, increased by 3.6, 39.4, 13.6 and 60.6%, compared to the 0.3GNPs/AZ91 composites, respectively. The improved mechanical properties of the MgO@GNPs/AZ91 composites could be attributed to the dislocation strengthening due to the geometrical mismatch and load transfer strengthening.