Effect of long-period stacking ordered phase on thermal stability of refined grains in Mg-RE-based alloys

Abstract

The refined grains in both as-cast Mg-10Y-1Zn-2Zr (WZ101 K, wt.%) and Mg-10Y-1Al (WA101, wt.%) alloys have been found to have superior thermal stability after solution treatment. Plate-shaped, but different polytypes of long-period stacking ordered (LPSO) phases distributed along grain boundaries are considered as the predominant inhibitors of grain growth. Based on the plate-shaped features of the LPSO phases, a modified Zener’s model is established and the predicted limiting grain sizes are in a good agreement with the experimental results. Therefore, this model has strong potential for designing advanced Mg-RE-based alloys with high strength and high creep resistance at high temperatures.

Keywords:

• magnesium alloys
• LPSO phase
• grain size
• thermal stability
• modified Zener’s model

Acknowledgements

The first author acknowledges the Chinese Scholarship Council (CSC) for financial support. The authors acknowledge the facilities, and the scientific and technical assistance, of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy and Microanalysis, The University of Queensland. The authors also acknowledge Dr Yuman Zhu for the access to the facilities of the Monash Centre for HAADF-STEM technique.