[SY-C10] First Principles Calculations of Dislocations in Model Engineering Alloys (Ni, Ni3Al, hcp-Ti, and a Refractory Metal BCC-HEA)
Invited
In order to understand the “chemistry of deformation” an adequate description of the strain field near the center (core) of dislocations is required. While continuum elasticity methods have been very successful in describing long-range stress fields of dislocations these methods diverge in the core region. Atomistic methods have shown that the forces produced at the dislocation core and their coupling to the applied stress can have a dramatic effect on plasticity. However, atomistic methods are limited by the fidelity of the assumed interaction model and for this reason are at best semi-empirical. Here the Lattice Greens Function is used with Density Functional Theory to calculate the equilibrium core structure of isolated screw dislocation in four model-engineering alloys. These include Ni, L12 Ni3Al, and a c+a pyramidal dislocation in hcp Ti. Pipe diffusion along the dissociated partial dislocations in Ni has been evaluated for self-diffusion and Co solutes. Recent progress extending a 3-d lattice Greens function to model screw dislocations in a refractory bcc high entropy (high concentration solid solutions) will be reviewed.