Screw dislocations in BCC transition metals: from ab initio modeling to yield criterion

Ab initio study of screw dislocations in Mo and ta: A new picture of plasticity in bcc transition metals

We report the first ab initio density-functional study of <111> screw dislocation cores in the bcc transition metals Mo and Ta. Our results suggest a new picture of bcc plasticity with symmetric and compact dislocation cores, contrary to the presently accepted picture based on continuum and interatomic potentials. Core energy scales in this new picture are in much better agreement with the Peie...

Ab initio calculations of the melting temperatures of refractory bcc metals.

We present ab initio calculations of the melting temperatures for bcc metals Nb, Ta and W. The calculations combine phase coexistence molecular dynamics (MD) simulations using classical embedded-atom method potentials and ab initio density functional theory free energy corrections. The calculated melting temperatures for Nb, Ta and W are, respectively, within 3%, 4%, and 7% of the experimental ...

Cascade morphology transition in bcc metals.

Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N(F) ~ E(MD)(b)). Response of different bcc metals can be compared in a consistent energy dom...

Ab initio work function of elemental metals.

Atomistic simulations of kinks in 1Õ2aŠ111‹ screw dislocations in bcc tantalum

Two types of equilibrium core structures ~denoted symmetric and asymmetric! for 1/2a^111& screw dislocations in bcc metals have been found in atomistic simulations. In asymmetric ~or polarized! cores, the central three atoms simultaneously translate along the Burgers vector direction. This collective displacement of core atoms is called polarization. In contrast, symmetric ~nonpolarized! cores ...