期刊
MATERIALS CHARACTERIZATION
卷 75, 期 -, 页码 108-114出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.matchar.2012.10.007
关键词
Ultrafine-grained materials; Aluminum matrix nanocomposite; Microstructure; Hot deformation; Dynamic recrystallization
An ultrafine-grained Al6063/Al2O3 (0.8 vol.%, 25 nm) nanocomposite was prepared via powder metallurgy route through reactive mechanical alloying and hot powder extrusion. Scanning electron microcopy, transmission electron microscopy, and back scattered electron diffraction analysis showed that the grain structure of the nanocomposite is trimodal and composed of nano-size grains (<0.1 mu m), ultrafine grains (0.1-1 mu m), and micron-size grains (>1 mu m) with random orientations. Evaluation of the mechanical properties of the nanocomposite based on the strengthening-mechanism models revealed that the yield strength of the ultrafine-grained nanocomposite is mainly controlled by the high-angle grain boundaries rather than nanometric alumina particles. Hot deformation behavior of the material at different temperatures and strain rates was studied by compression test and compared to coarse-grained Al6063 alloy. The activation energy of the hot deformation process for the nanocomposite was determined to be 291 kJ mol(-1), which is about 64% higher than that of the coarse-grained alloy. Detailed microstructural analysis revealed that dynamic recrystallization is responsible for the observed deformation softening in the ultrafine-grained nanocomposite. (c) 2012 Elsevier Inc. All rights reserved.
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