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Achieving ultra-high hardness of nanostructured Mg-8.2Gd-3.2Y-1.0Zn-0.4Zr alloy produced by a combination of high pressure torsion and ageing treatment

Research paper by W.T. Sun, X.G. Qiao; M.Y. Zheng; X.J. Zhao; H.W. Chen; N. Gao; M.J. Starink

Indexed on: 28 Jun '18Published on: 18 Jun '18Published in: Scripta Materialia



Abstract

Publication date: October 2018 Source:Scripta Materialia, Volume 155 Author(s): W.T. Sun, X.G. Qiao, M.Y. Zheng, X.J. Zhao, H.W. Chen, N. Gao, M.J. Starink A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%) alloy is subjected to a series of thermal and mechanical treatments involving solution treatment, artificial ageing to peak hardness, high pressure torsion (HPT) and a second artificial ageing. During HPT precipitates dissolve and during the final post-HPT ageing, the supersaturated solid solution decomposes and solutes segregate at grain boundaries. By employing this T6 + HPT + T5 treatment, the hardness increases to 156 ± 1 HV, which is much higher than that achieved by any other reported combination of thermal and thermo-mechanical processing of Mg alloys. The ultra-high hardness is due to the combined effects of solute segregation, grain refinement and high dislocation density. Graphical abstract