Optimum Design of Ultrahigh Strength Nanolayered Composites.

Kung, H. ; Embury, D. ; Hoagland, R. ; Misra, A. ; Verdeir, M. ; Hirth, J. ; Nastasi, M. ; Mitchell, T. ; Hundley, M. ; Hawley, M. ; Voter, A. ; Swaninarayan, S.

Technical Information Center Oak Ridge Tennessee

关键词: Composites;    Design;    Microstructure;    Mechanical properties;    Ultrahigh strength;   

RP-ID  :  PB2001103782

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Refinement of the microstructures in metallic multilayers from the micrometer-scale to the nanometer-scale often results in a break down of classical Hall-Petch model relating strength to the microstructural length scale. The critical length scale at which this behavior breaks down is investigated both experimentally and theoretically. We evaluated the microstructure and mechanical properties of Cu/Cr, Cu/Ni, and Cu/Nb multilayers having different shear moduli mismatch between layers and lattice misfit strain between layers by transmission electron microscopy and nanoindentation. Two-dimensional maps showing layer thickness and grain size ranges over which different deformation mechanisms operate were constructed using dislocation theory. The deformation mechanisms responsible for the breakdown of Hall-Petch behavior are discussed. By correlating the deformation mechanism maps with the experimental data, we show that these maps serve as guidelines for interpreting the scale-dependent deformation mechanisms in multilayers. Atomistic simulation was also used to evaluate the interaction between interfaces and glide dislocations to provide atomic scale insights into the deformation mechanisms.