Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7979157 | Materials Science and Engineering: A | 2015 | 8 Pages |
Abstract
A refined microstructure of Al-Mg-Sc-Zr alloy with an average grain size of ~3.7 μm and a portion of high angle boundaries of 69.2% was produced by free forging. Excellent superplastic ductility of â¥500% was achieved at a wide temperature range of 450~500 °C and relatively high strain rate range of 1Ã10â3~5Ã10â2 sâ1 in the Al-Mg-Sc-Zr alloy. A maximum elongation of 1593% was obtained at 475 °C and 1Ã10â3 sâ1. Moreover, the electron back scattered diffraction (EBSD) and the transmission electron microscopy (TEM) analyses showed that the excellent superplasticity can be attributed to the high fraction of high angle grain boundaries and the presence of Al3(Sc,Zr) dispersoids in the Al-Mg-Sc-Zr alloy microstructure. The analyses on the superplastic data revealed the presence of threshold stress, the coefficient of strain rate sensitivity of 0.5, and an activation energy of 83.9 kJ/mol-1. It indicated that the dominant deformation mechanism was grain boundary sliding. Based on this notion, a constitutive equation for Al-Mg-Sc-Zr alloy has been developed.
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Authors
Y.L. Duan, G.F. Xu, D. Xiao, L.Q. Zhou, Y. Deng, Z.M. Yin,