Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7882679 | Acta Materialia | 2014 | 10 Pages |
Abstract
First-principles quantum mechanics is an increasingly important tool for predicting material properties when designing novel alloys with optimized mechanical properties. In this study, we employ first-principles orbital-free density functional theory (OFDFT) to study plastic properties of body-centered-cubic (bcc) Mg-Li alloys as potential lightweight metals for use in, e.g., vehicle applications. The accuracy of the method as a predictive tool is benchmarked against the more accurate Kohn-Sham DFT (KSDFT). With a new analytic local electron-ion pseudopotential, OFDFT is shown to be comparable in accuracy to KSDFT with the conventional non-local pseudopotential for many properties of Mg-Li alloys, including lattice parameters and energy differences between phases. After this validation, we calculate generalized stacking fault energies (SFEs) of a perfect lattice and Peierls stresses (Ïp's) for dislocation motion in various bcc Mg-Li alloys. Such predictions have not been made previously with any level of theory. Based on analysis of SFE barriers, we propose that alloys with 31-50Â at.% Li will exhibit the greatest strength. Their Ïp's are predicted to be 0.18-0.31Â GPa. The Li concentration in this range (31-50Â at.%) has little impact on plastic properties of bcc Mg-Li alloys, while atomic-level disorder may decrease the Ïp. This range of Ïp is similar to the industrial goal for potential lightweight Mg alloys.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Ilgyou Shin, Emily A. Carter,