[SY-C11] Symposium C-11

[SY-C11] The effect of dislocation character on dislocation line tension in bcc tungsten and its impact on kink-pair enthalpy

^○David Cereceda¹, Vasily Bulatov³, Jaime Marian² (1.Dept. of Mechanical Engineering, Villanova University, United States of America, 2.Department of Materials Science and Engineering, University of California Los Angeles, United States of America, 3.Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, United States of America)

In addition to the well-characterized elastic contribution, the energy of a dislocation contains an inelastic, or ‘core’, term that reflects the loss of validity of elasticity theory at dislocation segments. While the elastic part is known to be symmetric about its maximum value for the edge orientation (minimum for screw), in bcc metals, the core energy displays an asymmetry that can be characterized using atomistic calculations. In kink-pair configurations on screw dislocations, this asymmetry leads to a difference in energy between ‘right’ and ‘left’ kinks that is not captured in elastic models. In this work, we calculate dislocation segment self-energies as a function of dislocation character in bcc tungsten and kink-pair enthalpies as a function of stress. To avoid finite-size artifacts in atomistic simulations, we develop continuum models of kink-pair configurations based on full elasticity and line tension approaches, parameterized with a substrate Peierls potential and dislocation self-energies obtained from atomistic calculations.

The elastic and line tension models represent specific situations of the environment of these kink-pair configurations, and we discuss our results in terms of the range of validity of each as well as the effect of self-energy asymmetry on kink-pair enthalpy. To match the continuum results to direct atomistic simulations, we vary the core radius of elasticity theory and discuss the implications of the values obtained.