A dislocation-based, strain–gradient–plasticity strengthening model for deformation processed metal–metal composites
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Deformation processed metal–metal composites (DMMCs) are high-strength, high-electrical conductivity composites developed by severe plastic deformation of two ductile metal phases. The extraordinarily high strength of DMMCs is underestimated using the rule of mixture (or volumetric weighted average) of conventionally work-hardened metals. In this article, a dislocation-density-based, strain–gradient–plasticity model is proposed to relate the strain-gradient effect with the geometrically necessary dislocations emanating from the interface to better predict the strength of DMMCs. The model prediction was compared with the experimental findings of Cu–Nb, Cu–Ta, and Al–Ti DMMC systems to verify the applicability of the new model. The results show that this model predicts the strength of DMMCs better than the rule-of-mixture model. The strain-gradient effect, responsible for the exceptionally high strength of heavily cold worked DMMCs, is dominant at large deformation strain since its characteristic microstructure length is comparable with the intrinsic material length.
KeywordsStrain Gradient Taylor Factor Intrinsic Material Length Entire Strain Range Conventional Plasticity Theory
The authors appreciate the financial support of the Iowa State University Research Foundation, the Electric Power Research Center of Iowa State University, and the Department of Energy through Ames Laboratory contract no. DE-AC02-07CH11358.
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