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Deformation and Fracture in Nanotwinned Materials

Huajian Gao (Brown University)

Symposium in honor of Rod Clifton on the occasion of his 75th Birthday

Mon 2:40 - 4:00

Salomon 101

The rapid development of synthesis and characterization of materials with feature sizes at nanoscale as well as unprecedented computational power have brought forth a new era of materials research in which experiments, modeling and simulations are performed side by side to probe the unique mechanical properties of nanostructured materials. Here we discuss a number of recent studies on deformation and fracture mechanisms in nanotwinned materials and structures, including the maximal strength of nanotwinned materials with equi-axed grains [1], nanoscale crack bridging by nanotwins in thin films [2], twin-spacing-induced ductile-brittle transition in nanotwinned nanopillars [3], and plastic anisotropy in columnar-grained nanotwinned materials [4]. In each study, there has been a strong synergy between theory and experiment, with new experimental findings driving advances in modeling and simulations, and new theoretical insights suggesting new experimental studies. The discussions will be organized around the current understandings based on existing experimental and theoretical efforts, as well as the outstanding questions that require further studies in the future. REFERENCES 1. X. Li, Y. Wei, L. Lu, K. Lu and H. Gao, 2010, “Dislocation Nucleation Governed Softening and Maximum Strength in Nanotwinned Metals,” Nature, Vol. 464, pp. 877-881. 2. S.W. Kim, X.Y. Li, H.J. Gao and S. Kumar, “In situ Observations of Crack Arrest and Bridging by Nanoscale Twins in Copper Thin Films,” 2012, Acta Materialia, Vol. 60, 2959–2972. 3. D.C. Jang, X.Y. Li, H.J. Gao and J.R. Greer, “Deformation Mechanisms in Nanotwinned Metal Nanopillars,” 2012, Nature Nanotechnology, Vol. 7, 594–601. 4. Z.S. You, X.Y. Li, L.J. Gui, Q.H. Lu, T. Zhu, H.J. Gao and L. Lu, “Plastic Anisotropy and Associated Deformation Mechanisms in Nanotwinned Metals,” 2013,Acta Materialia, Vol. 61, pp. 217–227.