MAE Seminar: Mechanics of Extremely Heterogeneous Materials

Abstract: Our recent studies of 3D-printed alloys (Nature Materials, 17, 63-71, 2018), high-entropy alloys with nanoscale chemical modulation (Nature, 574, 223-227, 2019), gradient nanotwinned metals (PNAS, 119, e2116808119, 2022), and several other heterogeneous materials raise fundamental questions on the role of extremely complex microstructural heterogeneities in controlling the mechanical behavior of these novel material systems. To address these questions, we combine mechanics modeling and experimental characterization for unraveling the extra strengthening effects of microstructural gradients and resultant plastic strain gradients relative to their homogeneous counterparts. Quantitative comparison is made between modeling and experimental results, highlighting the less appreciated notion of different types of back-stress hardening that operate in materials with extremely complex microstructural heterogeneities. In addition, we develop new experimental approaches, including in situ atomic resolution TEM (Science, 375, 1261–1265, 2022) and in situ synchrotron micro-diffraction X-ray (PNAS, 115, 483-488, 2018) to push the limits of characterizing heterogeneous microstructures at different length scales. Mechanistic insights are gained toward improved strength-ductility synergies in the design of extremely heterogeneous materials.

Bio: Ting Zhu is a Woodruff Professor in the Woodruff School of Mechanical Engineering at Georgia Institute of Technology. He received his Ph.D. in mechanical engineering from Massachusetts Institute of Technology in 2004. He worked as a postdoctoral associate at Harvard University before joining Georgia Tech in 2005. His research is focused on mechanics and materials modeling. He received the Sia Nemat-Nasser Early Career Award from the American Society of Mechanical Engineers and the Young Investigator Medal from the Society of Engineering Science.