TY - JOUR
T1 - Microstructural evolution in a nanocrystalline Cu-Ta alloy
T2 - A combined in-situ TEM and atomistic study
AU - Rajagopalan, M.
AU - Darling, K.
AU - Turnage, S.
AU - Koju, R. K.
AU - Hornbuckle, B.
AU - Mishin, Y.
AU - Solanki, Kiran
N1 - Funding Information:
M. Rajagopalan, S. Turnage, and K. N. Solanki are grateful for the financial support for this work from the Army Research Laboratory award number W911NF-15-2-0038 and would also like to thank the LeRoy Eyring Center for Solid State Science at Arizona State University. R. K. Koju and Y. Mishin were supported by the U.S. Army Research Office under contract number W911NF-15-1-007 .
Publisher Copyright:
© 2016 Elsevier Ltd
PY - 2017/1/5
Y1 - 2017/1/5
N2 - Under intense heating and/or deformation, pure nanocrystalline (NC) metals exhibit significant grain coarsening, thus preventing the study of length scale effects on their physical response under such conditions. Hence, in this study, we use in-situ TEM heating experiments, atomistic modeling along with elevated temperature compression tests on a thermally stabilized nanostructured Cu–10 at.% Ta alloy to assess the microstructural manifestations caused by changes in temperature. Results reveal the thermal stability attained in NC Cu-10 at.% Ta diverges from those observed for conventional coarse-grained metals and other NC metals. Macroscopically, the microstructure, such as Cu grain and Ta based cluster size resists evolving with temperature. However, local structural changes at the interface between the Ta based clusters and the Cu matrix have a profound effect on thermo-mechanical properties. The lattice misfit between the Ta clusters and the matrix tends to decrease at high temperatures, promoting better coherency. In other words, the misfit strain was found to decrease monotonically from 12.9% to 4.0% with increase in temperature, leading to a significant change in flow stress, despite which (strength) remains greater than all known NC metals. Overall, the evolution of such fine structures is critical for developing NC alloys with exceptional thermo-mechanical properties.
AB - Under intense heating and/or deformation, pure nanocrystalline (NC) metals exhibit significant grain coarsening, thus preventing the study of length scale effects on their physical response under such conditions. Hence, in this study, we use in-situ TEM heating experiments, atomistic modeling along with elevated temperature compression tests on a thermally stabilized nanostructured Cu–10 at.% Ta alloy to assess the microstructural manifestations caused by changes in temperature. Results reveal the thermal stability attained in NC Cu-10 at.% Ta diverges from those observed for conventional coarse-grained metals and other NC metals. Macroscopically, the microstructure, such as Cu grain and Ta based cluster size resists evolving with temperature. However, local structural changes at the interface between the Ta based clusters and the Cu matrix have a profound effect on thermo-mechanical properties. The lattice misfit between the Ta clusters and the matrix tends to decrease at high temperatures, promoting better coherency. In other words, the misfit strain was found to decrease monotonically from 12.9% to 4.0% with increase in temperature, leading to a significant change in flow stress, despite which (strength) remains greater than all known NC metals. Overall, the evolution of such fine structures is critical for developing NC alloys with exceptional thermo-mechanical properties.
KW - Atomistic
KW - In situ TEM
KW - Misfit strain
KW - Nanocrystalline
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U2 - 10.1016/j.matdes.2016.10.020
DO - 10.1016/j.matdes.2016.10.020
M3 - Article
AN - SCOPUS:84991693272
SN - 0264-1275
VL - 113
SP - 178
EP - 185
JO - Materials and Design
JF - Materials and Design
ER -