Microscopic Analysis of the Synergistic Mechanism of Strength and Toughness of Magnesium Alloys Reinforced by Graphene Nanoplatelets

In order to examine the influence of graphene nanoplatelet (GNP) incorporation on the microstructure and tensile characteristics of AZ31 magnesium alloys, a dispersion processing method was employed to prepare magnesium matrix composites (GNPs/AZ31) with varying mass fractions of GNPs, specifically 0.1 wt.%, 0.3 wt.%, and 0.6 wt.%. Uniaxial tensile loading tests were conducted to evaluate and compare the effects of different GNP concentrations on the GNPs/AZ31 properties, focusing on tensile strength, yield strength, elongation, and fracture work. Additionally, microstructural characterization techniques, including optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, were utilized to investigate the microstructural evolution of the GNPs/AZ31 in terms of grain size, composition, phase distribution, dislocation density, and texture. The results from the uniaxial tensile tests indicated a synergistic enhancement in both strength and toughness of the GNPs/AZ31 with increasing GNP content. Notably, at a GNP concentration of 0.6 wt.%, the GNPs/AZ31 exhibited tensile strength, yield strength, elongation, and fracture work values of 360 MPa, 253 MPa, 23.7%, and 72 J m⁻³, respectively. Microstructural analysis indicates that the GNPs are evenly dispersed throughout the GNPs/AZ31. As the quantity of GNPs increases, there is a corresponding reduction in the grain size; concurrently, there is an increase in dislocation density. This phenomenon is advantageous for enhancing the strength of the GNPs/AZ31. Furthermore, the texture intensity of the (0002) basal plane exhibits a slight reduction in the GNPs/AZ31, which promotes the activation of multiple crystal slip systems and enhances the plasticity of the material. This study may provide significant experimental data which could facilitate the advancement of high-performance GNPs/AZ31 and enhance the utilization of AZ31 magnesium alloy in aerospace, automotive, and consumer electronics applications.