Strengthening in Metal/Graphene Composites: Capturing the Transition from Interface to Precipitate Hardening

Abstract

A promising materials engineering method for improving the strength of crystalline materials is to add obstacles to dislocation motion that induce interface hardening (IH) or precipitate hardening (PH). In this study, molecular dynamics simulations are performed for Ni/graphene composites, revealing for the first time that graphene can strengthen the Ni matrix not only strictly via IH or PH but also through a continuous transition between the two. When graphene behaves like an interface, dislocation pileups form, whereas when it behaves as a precipitate, complex Orowan looping occurs by dislocation cross-slip. IH transitions to PH when the integrity of the graphene-dislocation configuration (GDC) deteriorates, leading to a reduced strengthening effect. Furthermore, the deformation of graphene is found to be an effective signature to indicate the real-time strengthening. This observation relates the graphene strengthening effect on metals to a combination of parameters, such as the GDC integrity, graphene deformation, and dislocation evolution, opening an avenue to tune the mechanical properties by controlling the dislocation movements and manipulating the dislocation–obstacle interaction mechanisms.

Machine Learning-Based Prediction of Mechanical Properties and Performance of Nickel–Graphene Nanocomposites Using Molecular Dynamics Simulation Data

“…In our case, dislocation absorption predominates. Several studies 45,46 also support the occurrence of dislocation absorption-induced hardness reduction, even when graphene reinforcement is predominant. In addition, this phenomenon might be influenced by the crystal type of the composite material.…”

Microstructure Evolution of Graphene and the Corresponding Effect on the Mechanical/Electrical Properties of Graphene/Cu Composite during Rolling Treatment

“…In addition, the degree of graphene dispersion is higher and more uniform at low temperature rolling. Fei [ 39 , 40 , 41 ] and Zhao [ 14 , 42 ] et al found that graphene has a hindering effect on the movement of dislocations in the metal matrix. When the degree of graphene dispersion is higher, the locking effect on dislocations is more obvious, which also contributes more to the hardness enhancement of the material.…”

Graphene Oxide-Induced Substantial Strengthening of High-Entropy Alloy Revealed by Micropillar Compression and Molecular Dynamics Simulation

“…Then, the nanopillars were compressed along the z -axis by a virtual rigid plane at a rate of 12 m/s under the canonical (NVT) ensemble. Notably, such a virtual plane was realized by the repulsive force model, as shown in Equation ( 2 ), which has been extensively employed in previous studies [ 19 , 35 , 43 ]. For comparison, the pure HEA nanopillar was compressed under the same simulation conditions.…”