Moving beyond pure metals in multi-scale modeling: effects of alloying on strength

This work focuses on the development of a strength model for BCC alloys that is informed by cross-scale molecular dynamics and experimental measurements. The model builds on previous Livermore multi-scale strength model forms, extending here to account for solid solution strengthening. We also introduce a new model of dislocation density evolution, which is based on the behavior of dislocation avalanches. The dislocation avalanche model captures (i) an upturn in saturation dislocation density and flow stress at a strain rate of about 10⁴/s, and (ii) higher dislocation densities in solute fields of higher concentration. The model is calibrated to Ta-W experimental and molecular dynamics data at strain rates ranging from 10^-3 to 10⁸/s. Model predictions of alloy strengthening are considered in idealized simulations of ramp wave compression, with comparison to recent x-ray-based measurements of Ta-W lattice strain.



This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. (LLNL-ABS-2002712).