Single layer graphene controlled surface and bulk indentation plasticity in copper

Abstract

The impact of graphene reinforcement on the mechanical properties of metals has been a subject of investigation over the last decade in surface applications to mitigate the impact of tribological loadings or for strengthening purposes when dispersed into a bulk material. Here, the effect on the plastic indentation response of a single graphene layer grown on Cu is analyzed for two configurations: one with graphene at the surface, the other with graphene sandwiched under a 100 nm thick Cu cap layer.Nanoindentation under both displacement and load control conditions show both earlier and shorter popin excursions compared to systems without graphene. Atomic force microscopy reveals much smoother pile-ups with no slip traces in the presence of a surface graphene layer. The configuration with the intercalated graphene layer appears as an ideal elementary system to address bulk hardening mechanisms by indentation testing. Transmission electron microscopy (TEM) cross-sections below indents show more diffuse and homogenous dislocation activity in the presence of graphene. 3D dislocation dynamics simulations allow unraveling of the origin of these 3D complex phenomena and prove that the collective dislocation mechanisms are dominantly controlled by the strong back stress caused by the graphene barrier. These results provide a quantitative understanding of the impact of graphene on dislocation mechanisms for both surface and bulk applications, but with an impact that is not as large as anticipated from other studies or general literature claims.

How Good Are the Performances of Graphene and Boron Nitride Against the Wear of Copper?

“…They showed that the experimentally observed effects could be rationalized based on the large back-stress induced by the graphene layer that acts as an impermeable barrier and leads to the delocalization of plasticity events. While these results agree with the ones presented in Reference [20], the authors in Reference [21] also found that the onset of plastic deformation of copper occurs at a lower load level in the presence of a graphene monolayer. This is in contrast to results in References [19,20].…”

“…There, sudden jumps in the friction force signal were observed upon graphene rupture that was preceded by plasticity events in underlying platinum. The load-carrying effect of graphene grown on copper has further been simulated and measured during nanoindentation experiments [20,21]. In Reference [20], the authors performed molecular dynamic simulations of nanoindentation to better understand the effects of graphene on the plastic deformation of copper.…”

“…Furthermore, the authors explained their observations based on the impermeability of the graphene-copper interface to dislocations that inhibit the formation of slip steps on the surface. In Reference [21], the authors showed that the presence of graphene on copper reduces the average pop-in length during indentation and results in a more homogeneous distribution of dislocations below an indent and less prominent pile-ups around an indent. The authors further performed three-dimensional dislocation dynamics simulations.…”

Промислове Нанесення Покриттів На Втулку Підшипника За Технологією Електроіскрового Легування

“…Graphene has been used to improve tribological property due to its extraordinary properties [18][19][20]. Graphene oxide (GO) is considered as a promising material for reducing friction and wear, owing to its structural features [21].…”

Delamination of MoS2/SiO2 interfaces under nanoindentation

“…29,30 So far, the mechanical behaviour of graphene mounted on various substrates has been widely investigated using nanoindentation experiments and simulations. [31][32][33][34][35][36][37] The results have shown that the interaction between graphene and the substrate can greatly affect the mechanical properties of graphene and its applications. Thus, it is reasonable to expect that the substrate may similarly have an impact on the mechanical behaviour and failure mechanisms of supported MoS 2 .…”