First-Principles Study of Full a-Dislocations in Pure Magnesium
T. Fan1, L. Luo1, L. Ma2, B. Tang1,2, L. Peng3, W. Ding3
1Xiangtan University, Hunan Province 411105, China
2School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
3Shanghai Jiaotong University, Shanghai 200030, China
Keywords: magnesium, dislocation, Peierls-Nabarro model, generalized stacking fault energy, Peierls stress
Abstract
Full a-dislocations on the (0001) basal plane, (1010) prismatic plane, and (1011) and (1012) pyramidal planes in pure magnesium are investigated by using the Peierls-Nabarro model combined with generalized stacking fault (GSF) energies from first-principles calculations. The results show that the (1011)1120 and (1012)1120 slip modes have nearly the same GSF energy barriers, which are obviously larger than the GSF energy barriers of the (0001) 1120 and (1010)1120 slip modes. For both edge and screw full dislocations, the maximum dislocation densities, Peierls energies, and stresses of dislocations on the (1010), (0001), (1011), and (1012) planes eventually increase. Moreover, the Peierls energies and the stresses of screw full dislocations are always lower than those of edge full dislocations for all slip systems. Dislocations on the (1011) and (1012) pyramidal planes possess smaller core energies, while the (1010) prismatic plane has the largest ones, implying that the formation of full dislocations on the (1010) plane is more difficult.
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