Revealing the toughening mechanisms in graphene/tungsten nanocomposites with hierarchical nacre-like structures

Abstract

The integration of traditional “brick-and-mortar” structure with graphene additives demonstrates remarkable efficiency for enhancing the toughness of metal matrix composites. This study proposes five different types of graphene/tungsten (Gr/W) nanocomposites that incorporate hierarchical nacre-like structures, leveraging the tensile toughness benefits of both nacre and graphene in metal matrix composites. To evaluate the mechanical properties and microstructure evolution process of Gr/W nanocomposites, series of atomistic simulations are carried out. It is found that Gr/W nanocomposites with hierarchical nacre-like structures possess superior tensile toughness compared to pure W, albeit at the cost of partial strength reduction. The presence of Gr “mortars” between W “bricks” is crucial in improving toughness through shear deformation accommodation. A larger volume percentage of Gr “mortars” will promote the tensile toughness increment of Gr/W nanocomposites. In contrast to pure W, the Gr/W samples exhibit no twin boundary migration, as the shear strain in W bricks is negligible. And the tensile toughness of Gr/W nanocomposites exhibits a negative correlation with temperature. Specifically, with the temperature increases from 300 to 1500 K, the toughness decreases from 0.971 to 0.304 GJ/m3. The proposed hierarchical nacre-like structures could provide valuable insights for the design of other metal matrix composites with robust performances.