Solute-Induced Heterogeneities in the Deformation Behavior of Face- Centered Cubic Solid Solutions

The competition between deformation mechanisms underpins the mesoscale plastic response of materials. The onset of deformation mechanisms has been well-documented in the literature through models based on phenomenological relations which are often related to energy barriers associated with different defect structures. In this work, a framework based on the kinetic Monte Carlo (kMC) approach is developed to predict the evolution of mechanism competition beyond incipient stages using the generalized planar fault energy (GPFE) landscape and intrinsic material properties as inputs. These results are leveraged to derive an analytical model for the evolution of the fault fraction, fault densities, and partitioning of plastic strains among deformation mechanisms. The application of the proposed models led to the development of a descriptor of competition for different mechanisms under extended deformation. The tools developed here shed light on the deformation behavior of pure FCC metals but there is a limited understanding of how these mechanisms evolve in solid solutions. To address this shortcoming, constitutive frameworks that study the evolution of deformation behavior in solid solutions are developed. The varied atomic arrangements of solid solutions introduce fluctuations in the potential energy (PE) landscapes. The effect of local fluctuations in the GPFE landscape on the evolution of deformation twinning (DT) microstructures in randomly arranged FCC solid solutions is examined. The predictions of the deformation morphologies were validated using molecular dynamics (MD) simulations. These contributions provide frameworks to study the deformation behavior of materials; however, they are based on computationally expensive simulations making it difficult to explore all system compositions. To that end, this thesis provides statistical equations to predict PE statistics making it possible to rapidly chart material properties in the vast compositional space of solid solutions. Using these statistical relations energy landscapes like cohesive energy, GPFE, and vacancy energies are studied. The most important contributions of this thesis are rapid analytical models that explore energy landscapes of solid solutions and predict mechanism competition evolution in FCC metals and alloys. These products can be used to aid future materials design by passing nanoscale deformation physics upwards to the continuum scales.