Abstract

A model is proposed that describes plastic deformation in metal/graphene composites with a bimodal grain size distribution of the metallic matrix. Within the model, dislocation pile-ups are generated in large grains at Frank–Read sources, and their stresses promote dislocation motion within the nanocrystalline/ultrafine-grained phase. Also, the presence of graphene gives rise to the mechanisms of strengthening, such as the load transfer to graphene platelets, thermal-mismatch-induced strengthening and Orowan strengthening, as well as to back stress hardening. We demonstrated that the strengthening and strain hardening in bimodal metal/graphene composites are dominated by the Orowan strengthening and back stress hardening. The results also indicate that regardless of the lateral size of graphene platelets, bimodal metal/graphene composites can simultaneously have high yield strength and large uniform deformation but the values of the yield strength and critical uniform deformation are higher in the case of small graphene platelets.

中文翻译：

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具有双峰粒度分布的金属/石墨烯复合材料的强度和延展性增强模型

抽象的

提出了一个描述金属/石墨烯复合材料中塑性变形的模型，该模型具有金属基体的双峰粒度分布。在该模型中，Frank-Read源的大晶粒中产生了位错堆积，其应力促进了纳米晶/超细晶相内的位错运动。同样，石墨烯的存在引起了增强机制，例如负载转移至石墨烯血小板，热失配引起的增强和Orowan增强，以及背应力硬化。我们证明了双峰金属/石墨烯复合材料的强化和应变硬化主要由Orowan强化和背应力硬化所主导。结果还表明，无论石墨烯血小板的横向尺寸如何，