Abstract:
The modeling of dislocations and their mobility using ab initio density functional theory (DFT) calculations has made tremendous progress these past few years, in part thanks to an increase in computing power, but also because of methodological developments, including methods to correct the energy for elastic interactions between periodic images.
In this seminar, I will review recent advances in dislocation plasticity based on ab initio calculations, mainly in body centered cubic (BCC) and hexagonal close packed (HCP) metals. In BCC transition metals, I will discuss our new understanding of the screw dislocation two-dimensional Peierls potential and its close connection to the well-known deviations from the Schmid law.
Alloying effects on the dislocation core structure and mobility will be addressed, highlighting how interstitial atoms can restructure the screw dislocation core. In HCP metals, I will show how DFT calculations identified stable and metastable dislocation cores, how these cores are related to slip in different slip systems and how an inversion of stability between a glissile and a sessile core explains the profoundly different plastic behaviors observed by in-situ TEM in Zr and Ti.
I hope that this talk can serve as a basis for discussion on the challenges and opportunities to bridge these small-scale simulations with higher-scale models and simulations.

References:
Rodney D., Clouet E., Ventelon L., Pizzagalli L., Willaime F. ‘Ab initio modeling of dislocation core properties in metals and semiconductors’
Acta Materialia 124 (2017) 63.
Dezerald L., Rodney D., Clouet E., Ventelon L., Willaime F. ‘Plastic anisotropy and dislocation trajectory in BCC metals’
Nature Communications 7 (2016) 11695.
Ventelon L., Lüthi B., Clouet E., Proville L., Legrand B., Rodney D., Willaime F. ‘Dislocation core reconstruction induced by carbon segregation in bcc iron’
Physical Review B (Rapid Communications) 91 (2015) 220102.
Clouet E., Caillard D., Chaari N., Onimus F., Rodney D. ‘Dislocation locking versus easy glide in titanium and zirconium’
Nature Materials 14 (2015) 931.