Revisiting the evolution behaviors of beta ' phase in Mg-Nd and Mg-Y alloys

The beta' phase is considered as one of the most effective strengthening phases in Mg-RE based alloys. In this paper, we investigate the evolution behaviors of two typical beta' phases, i.e. beta(s)' and beta(l)', in the Mg-1.5Nd and Mg-11Y alloys during ageing at 225 degrees C, respectively. During the beta' evolution, the RE composition in precipitates is increased from Mg7RE (beta') to Mg3RE (beta '' or beta(t)'') due to the decrease of formation energy. The beta(s)' phase could be transformed into the D0(19) -beta '' phase in the Mg-1.5Nd alloy, while the beta(l)' phase could be transformed into the beta(t)'' phase. The evolution behaviors of beta' phases in Mg-Nd and Mg-Y systems are rationalized by density functional theory (DFT) calculations, which will offer a guideline to regulate the structure and distribution of precipitates in Mg-RE based alloys.

Automated summary

This study investigated the evolution behaviors of beta' phases in Mg-RE based alloys, revealing that beta(s)' and beta(l)' phases can transform into different phases during ageing at 225 degrees C. Density functional theory calculations were used to rationalize the evolution behaviors, providing guidance for controlling the structure and distribution of precipitates in Mg-RE based alloys.