【摘要】 针对SiC_p/Mg-6Zn-3Al镁基复合材料，建立了基于真实微观组织的二维有限元力学分析模型，采用模拟和试验相结合的方法深入研究了复合材料的变形和断裂行为，以及颗粒尺寸对材料力学性能的影响。结果表明，随着颗粒尺寸增加，复合材料的强度、塑性及加工硬化率均有下降。模拟分析表明，平面应变加载下模拟曲线与试验结果较吻合，拉伸过程中应力集中多发生在颗粒尖角及凹陷处；应力和应变均沿与拉伸方向呈45°“X”状分布，中心处应力或应变的叠加会导致其成为裂纹源的形核位置。裂纹沿着高应力或应变区域扩展，导致局部区域应力的释放。颗粒尺寸的增加导致材料性能降低的本质在于大尺寸颗粒的载荷传递效果大幅降低。更多还原

【Abstract】 A two-dimensional finite element mechanical analysis model based on real microstructures was established for SiC_p/Mg-6Zn-3Al magnesium matrix composites. The deformation and fracture behavior of the composites and the influence of grain size on mechanical properties were investigated intensively by combining simulation and experiment. The results indicate that the strength, plasticity and work hardening rate of the composites are all decreased with the increase of grain size. The simulation analysis reveals that the simulation curve under plane strain loading is in consistent with the experimental ones, and stress concentration often occurs in the sharp corners and depressions of grain during the tensile process. The stress and strain are distributed in an “X” shape along 45 ° from the tensile direction, and the superposition of the stress or strain at the center become the nucleation location of crack source. The crack is propagated along the high stress or strain area, leading to the release of local regional stress. The essence of grain size increase resulting in the property reduction is the great decline of load transfer effect of large grain.更多还原