First Principles and Multiscale Modeling of Spallation and Erosion of Gun Tubes

摘要

This represents the final report for two years of research at UCLA by the PI and her group on the gun tube erosion problem. In the past two years, they created new quantum-based simulation tools (both first principles and multiscale modeling techniques) and investigated surface, bulk, and interfacial materials aspects of the gun tube erosion problem. In brief, they developed: (i) two new versions of their spin-dependent pseudopotential theory that provides a more ab initio and more accurate description of magnetic transition metals such as Fe, (ii) a multiscale model that couples chemistry and mechanics to study hydrogen embrittlement in steel, and (iii) a scheme for calculating fracture energies of materials with mobile impurities (such as hydrogen in iron). They applied our spin-dependent pseudopotential theory to evaluate magnetism of vanadium surfaces, and applied density functional theory (DFT) to evaluate TiC and ZrC as possible protective coatings for steel. They also characterized via DFT the energetics and kinetics of how hydrogen and carbon adsorb and diffuse into iron, the structure and relative stability of cementite (iron carbide) surfaces, as well as predicting pathways for CO and H2S adsorption, diffusion, and dissociation on Fe surfaces.