Revealing the mechanisms of deformation using advanced characterization techniques
Michael J. Mills, Department of Materials Science and Engineering, The Ohio State University, Columbus, USA
The international initiative on Integrated Computational Materials Engineering holds great promise for accelerating the insertion of new materials in high performance structural applications. Achieving this aim relies upon the fidelity of materials models and their ability to capture the connectivity between processing, microstructure and performance. This presentation will focus on advancements in our ability to characterize deformation mechanisms at finer length-scales – from atomic to grain-level behavior. For instance, in the Ni-base superalloys, a surprising variety of governing deformation mechanisms are observed as a function of microstructure and deformation condition. In particular, at elevated temperature, the strain rate and temperature dependence of deformation depends on the onset of several mechanisms that are distinct from the “classic” shearing processes that dominates at lower temperature. Using electron-microscopy-based techniques, new insights into the governing deformation mechanisms in several important structural materials are being developed. Another example to be discussed is the high temperature shape memory alloys for which the interplay between dislocation plasticity and martensitic transformation determines the macroscopic behavior that is highly desirable for new actuator applications. The important role played by characterization in motivating modeling at several important length-scales (including atomistic, phase field and crystal plasticity) will also be discussed.