Effect of Sc and Er additions on superplastic ductilities in Al-Mg-Mn-Zr alloy

• Published in: Journal of Central South University Vol. 23; no. 6; pp. 1283 - 1292
• Main Authors: Duan, Yu-lu, Qian, Jian, Xiao, Dan, Cui, Xue-min, Xu, Guo-fu
• Format: Journal Article
• Language: English
• Published: Changsha Central South University 01-06-2016
• Subjects: Chemical and Environmental Engineering; Engineering; Materials; Metallic Materials; Metallurgy; Al-Mg-Sc alloy; Al-Mg-Er alloy; microstructure; superplasticity
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-016-3178-x

The superplasticity of Al-6Mg-0.4Mn-0.25Sc-0.12Zr and Al-6Mg-0.4Mn-0.25Er-0.12Zr (mass fraction, %) alloys sheet was investigated, and the effect of Sc and Er was discussed. The results show that the superplastic ductilities of Al-Mg-Mn-Sc-Zr alloy was higher than that of Al-Mg-Mn-Er-Zr alloy at a wide temperature range of 400-540 °C and high strain rate range of 1.67×10
-4
-1.67×10
-1
s
-1
. A maximum elongation 673% is obtained at 520 °C and 1.67×10
-3
s
-1
in the Sc-containing alloy; while the Er-containing alloy only gets a maximum elongation 253% at 520 °C and 1.67×10
-3
s
-1
. Moreover, the average stress exponent of Sc-containing alloy is about 2.84, which is smaller than that of Er-containing alloy (3.64). Besides, the activation energies of the Sc-containing and Er-containing alloy are 84.8 kJ/mol and 87.2 kJ/mol, respectively. It is indicated that grain boundary sliding is the dominant mechanism during tensile deformation. According to microstructure examination, the better superplasticity of Sc-containing alloy may be attributed to the presence of Al
3
(Sc, Zr) dispersoids, which can inhibit recrystallization and grain growth effectively.