Increasing nanoparticle volume fraction has been proved to be effective in improving the strength of nanoparticle reinforced Al matrix nanocomposite. However, the underlying mechanisms for the ultrahigh strength of those nanocomposites with high volume fraction (> 10 vol.%) nanoparticles are short of experimental research. In this study, the strengthening mechanisms of high strength Al matrix nanocomposite reinforced with 15 vol.% Al₂O₃ nanoparticles were investigated experimentally and analyzed theoretically. The results show that the thermal mismatch induced geometrically necessary dislocations exhibit a negligible strengthening effect, because of their low density in the nanocomposite that is contradiction to the conventional dislocation punch model. Orowan mechanism makes a major strengthening contribution in view of the deformation process dominated by nanoparticle-dislocation interactions due to the extreme pinning effect of nanoparticles on dislocation motion. In addition, the several mechanisms including grain boundary strengthening, load transfer strengthening, and elastic modulus mismatch induced dislocation strengthening contribute to the strength increase.

已证明增加纳米颗粒体积分数可有效提高纳米颗粒增强铝基纳米复合材料的强度。然而，这些具有高体积分数（> 10 vol.%）纳米颗粒的纳米复合材料超高强度的潜在机制缺乏实验研究。在本研究中，15 vol.% Al ₂ O ₃增强的高强度铝基纳米复合材料的强化机制对纳米颗粒进行了实验研究和理论分析。结果表明，热失配引起的几何必要位错的强化效果可以忽略不计，因为它们在纳米复合材料中的密度低，这与传统的位错冲压模型相矛盾。由于纳米颗粒对位错运动的极端钉扎效应，纳米颗粒-位错相互作用主导了变形过程，因此 Orowan 机制对强化作用做出了重大贡献。此外，包括晶界强化、载荷传递强化和弹性模量失配诱导位错强化在内的几种机制有助于强度的增加。