Effect of grain boundary segregation of rare earth element on deformation behavior of Mg alloys

S Li and HY Song, JOURNAL OF APPLIED PHYSICS, 136, 064301 (2024).

DOI: 10.1063/5.0219468

Alloying with rare earth (RE) elements is an effective way to improve the mechanical properties of the Mg alloys. However, the strengthening mechanism of RE element Y on the Mg alloys still needs to be further revealed. The effect of grain boundary (GB) segregation of RE element Y on the mechanical properties and the GB stability of the Mg alloys are investigated by the molecular dynamics simulation method. The results show that the GB segregation of Y atoms can significantly increase the yield strength and GB stability of the Mg alloys. The higher the content of Y atoms at the GB, the stronger the stability of the GB and the higher the strength of the alloys. The results also show that the GBs thicken significantly with increasing Y content at the GBs, which is attributed to the diffusion of Y atoms, leading to the solid-state amorphization of the Mg alloys. The results indicate that with the increase of Y content at the GBs, the Mg alloys undergo a transition from the plastic deformation dominated by the co-sliding of GBs and dislocations to the slip of dislocations only. This work provides a theoretical basis for the design and preparation of high-performance Mg alloys.

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