Dislocations and Plasticity in Bcc Transition Metals at High Pressure

Download or read book Dislocations and Plasticity in Bcc Transition Metals at High Pressure written by and published by . This book was released on 2009 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using first-principles electronic structure calculations, quantum-based atomistic simulations and atomistically informed dislocation dynamics (DD) simulations, we have studied individual dislocation behavior and the multiscale modeling of single-crystal plasticity in the prototype bcc transition metals Ta, Mo and V under both ambient and high pressure conditions. The primary focus in this work is on the pressure-dependent structure, mobility and interaction of a/2111 screw dislocations, which dominate the plastic deformation properties of these materials. At the electronic scale, first-principles calculations of elasticity, ideal strength and generalized stacking fault energy surfaces have been used to validate quantum-based multi-ion interatomic potentials. At the atomistic scale, these potentials have been used in flexible Green's function boundary condition simulations to study the core structure, Peierls stress?{sub P}, thermally activated kink-pair formation and mobility below?{sub P}, and phonon-drag mobility above?{sub P}. These results have then been distilled into analytic velocity laws and used directly in predictive microscale DD simulations of flow stress and resolved yield stress over wide ranges of pressure, temperature and strain rate.