Journal of Magnesium and Alloys (May 2023)

Development and characteristics of a low rare-earth containing magnesium alloy with high strength-ductility synergy

  • Zijian Yu,
  • Xi Xu,
  • Kang Shi,
  • Baotian Du,
  • Xiuzhu Han,
  • Tao Xiao,
  • Shubo Li,
  • Ke Liu,
  • Wenbo Du

Journal volume & issue
Vol. 11, no. 5
pp. 1629 – 1642

Abstract

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In this study, we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr (wt%) alloy with high strength-ductility synergy by combined processes of hot extrusion, hot rolling and ageing. This alloy exhibits an excellent strength-ductility balance (UTS of 345 ± 2.0 MPa, TYS of 301 ± 5.0 MPa and EL of 9.2 ± 1.9%), which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy. A long-range chain-like structure consisting of β′ phase, βH phase, βM phase and zig-zag atomic columns is observed for the first time in the studied alloy. The combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries, and makes the deformed grains dominate in the alloy strengthening. Under this circumstance, the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains, which plays a key role in the concurrent strengthening and toughening of the alloy. The present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.

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