颗粒增强金属基复合材料的强化机理研究现状

Research Status on Strengthening Mechanism of Particle-reinforced Metal Matrix Composites

本文总结了较低颗粒体积分数(≤14%)的颗粒增强金属基复合材料中主要存在的Orowan强化应力、位错强化应力、颗粒承载强化应力和其他强化应力的理论研究现状,以及各项强化应力之间的耦合关系。得出以下结论:(1)降低颗粒尺寸、提高颗粒体积分数和提高颗粒分布均匀性能够同时提高Orowan强化应力和位错强化应力,提高颗粒体积分数还能够提高颗粒承载强化应力;(2)采用微观非均匀分布的颗粒包围金属基体的材料设计方法,通过提高颗粒承载强化应力和提供塑性形变区,能够进一步提高复合材料屈服强度和延展性;(3)晶界强化效应和晶格摩擦应力对复合材料屈服强度也有贡献,但较少通过增强这两项强化效应提高复合材料屈服强度,通常可忽略复合材料中的固溶强化效应;(4)各项强化应力的耦合关系存在线性叠加、乘积叠加和均方根叠加3种形式。线性叠加和乘积叠加适用于纳米颗粒增强金属基复合材料,其中乘积叠加关系应用效果更好;均方根叠加主要应用于微米级颗粒增强金属基复合材料。

The research status on theoretic models and the coupling relationships of Orowan strengthening, dislocation strengthening, load-bearing effect of the reinforcement strengthening and others strengthening are successfully described in this study for particle-reinforced metal matrix composites（MMCs） with a volume fraction lower than 14%. Some conclusions can be obtained： Orowan strengthening and dislocation strengthening stress can be enhanced by increasing volume fraction, decreasing size of reinforcement and improving homogeneous distribution of reinforcement, load-bearing strengthening stress can also be enhanced by increasing volume fraction; yield strength and ductibility of MMCs can be enhanced much more by increasing load-bearing strengthening stress and plastic deformation region and adopting the material design method of metal matrix surrounded by particles with microstructural inhomogenous distribution;grain boundary strengthening and Peierls-Nabarro stress can also affect the yield strength of MMCs as a part of matrix strengthening, solid solution strengthening can be ignored usually; there are three coupling relationships for the sum strengthening contributions： linear summation, multiplicative combination and the root of the sum of the squares. The linear summation and multiplicative combination can be applied to nanoparticle-reinforced MMCs, the linear summation is generally applicable in the case when there are few factors influencing the strength, the multiplicative combination is the most commonly used method. The root of the sum of the squares is applied to micronparticle-reinforced MMCs.