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 th...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.% Al_(2)O_(3) 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.展开更多
基金financially supported by the Key Research and Development Project in Sichuan Province(Grant No.2020YFG0140)the Fundamental Research Funds for the Central Universities(Grant No.2682020CX47)+1 种基金the China Postdoctoral Science Foundation(Grant No.2020M683349)。
文摘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.% Al_(2)O_(3) 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.
