  Predicting the structural response of advanced multiphase alloys and
understanding the underlying microscopic mechanisms that are responsible for it
are two critically important roles modeling plays in alloy development. An
alloys demonstration of superior properties, such as high strength, creep
resistance, high ductility, and fracture toughness, is not sufficient to secure
its use in widespread application. Still, a good model is needed, to take
measurable alloy properties, such as microstructure and chemical composition,
and forecast how the alloy will perform in specified mechanical deformation
conditions, including temperature, time, and rate. In this bulletin, we
highlight recent achievements by multiscale modeling in elucidating the coupled
effects of alloying, microstructure, and the dynamics of mechanisms on the
mechanical properties of polycrystalline alloys. Much of the understanding
gained by these efforts relied on integration of computational tools that
varied over many length and time scales, from first principles density
functional theory, atomistic simulation methods, dislocation and defect theory,
micromechanics, phase field modeling, single crystal plasticity, and
polycrystalline plasticity.
