Abstract:

There is rising interest in the topic of microstructural evolution in metals in the materials’ engineering community, especially for aerospace applications, where lightweight and high strength materials are required for extreme conditions. Advances in the understanding and quantification of microstructural evolution will enable technological breakthroughs of importance to improvements in material properties and for the control and design of metal processing and shaping operations. In this context, the physical properties that emerge from the microstructural configuration of a material, and how the latter can evolve under severe plastic deformation, are key for an optimal design of metallic alloys and for tailoring ad hoc manufacture techniques. In this presentation we focus on fundamental aspects of micro- and nano-mechanics to present a thermodynamically consistent model that can be used to predict the microstructural evolution of polycrystalline metals subject to severe plastic deformation. Our model focuses on the grain refinement created by continuous dynamic recrystallization and on latent heat storage (the energy that remains stored in the microstructure) and saturation.  The model successfully predicts the final grain size that arises at large plastic strain, correctly predicts transitions from dislocation mediated plasticity to grain boundary sliding controlled deformation, and is consistent with measurements of heat generation during such modes of inelastic flow.

Biosketch:

Mattia Bacca obtained a “Laurea” in Civil Engineering in 2009 and a PhD in Structural and Mechanical Engineering in 2013, both at the University of Trento in Italy. He then joined the Mechanical Engineering Department of the University of California, Santa Barbara as a Postdoctoral Fellow. His research involves the study and the application of fundamental aspects of the mechanics and physics of solids, with a focus on the relationship between macroscopic materials’ properties and the materials’ architecture at the micro and nanoscale. His studies involve wave propagation in periodic media, homogenization of biphasic materials, metal physics, and bio-inspired dry adhesion. An additional aspect of his research concerns the mechanics of biological cells.