The fundamental understanding of the effects of rare earth(RE)on the phase transformation of Fe-based alloys is essential in the development of advanced RE-containing high strength steels.In this work,we investigated ...The fundamental understanding of the effects of rare earth(RE)on the phase transformation of Fe-based alloys is essential in the development of advanced RE-containing high strength steels.In this work,we investigated the effects of La and Ce on the martensitic phase transformation of Fe in terms of the driving force and minimum energy path(MEP)using the first-principles calculations.The calculations of formation energy show that the RE substitution increases the stabilization of fcc-Fe and decreases that of bcc-Fe,thus decreasing the driving force of phase transformation.Meanwhile,the analysis based on the generalized solid-state nudged elastic band(G-SSNEB)method indicates that in the RE-containing systems,an additional energy barrier appears when the phase transformation proceeds along the Bain transition path to c/a ratio of 1.14 in the FM state,which is associated with a sudden decrease in magnetization due to the hybridization between the orbits of the RE atoms and those of the nearest neighbor Fe atoms.The results of potential-energy surfaces(PES)confirm that magnetic ordering and lattice volume change simultaneously with the Bain transition,and in comparison to pure Fe,the variation between the onset and the end structural volumes of the phase transformation is slight for the REcontaining Fe systems.展开更多
基金Project supported by the National Natural Science Foundation of China(5196103052161008)+3 种基金the Natural Science Foundation of Inner Mongolia(2019MS05013)Youth Innovation Talent Project of Baotouthe Innovation Fund of Inner Mongolia University of Science and Technology(2019QDL-B15)the Central Government Guides Local Science and Technology Development Fund Projects of China。
文摘The fundamental understanding of the effects of rare earth(RE)on the phase transformation of Fe-based alloys is essential in the development of advanced RE-containing high strength steels.In this work,we investigated the effects of La and Ce on the martensitic phase transformation of Fe in terms of the driving force and minimum energy path(MEP)using the first-principles calculations.The calculations of formation energy show that the RE substitution increases the stabilization of fcc-Fe and decreases that of bcc-Fe,thus decreasing the driving force of phase transformation.Meanwhile,the analysis based on the generalized solid-state nudged elastic band(G-SSNEB)method indicates that in the RE-containing systems,an additional energy barrier appears when the phase transformation proceeds along the Bain transition path to c/a ratio of 1.14 in the FM state,which is associated with a sudden decrease in magnetization due to the hybridization between the orbits of the RE atoms and those of the nearest neighbor Fe atoms.The results of potential-energy surfaces(PES)confirm that magnetic ordering and lattice volume change simultaneously with the Bain transition,and in comparison to pure Fe,the variation between the onset and the end structural volumes of the phase transformation is slight for the REcontaining Fe systems.
