Solid solution strengthening and deformation behavior of single-phase Cu-base alloys under tribological load

Abstract

The influence of solid solution strengthening on the evolution of the microstructure under cyclic dry sliding is still not fully rationalized. One reason is that alloying needed for solid solution strengthening alters the stacking fault energy at the same time and, hence, the mode of dislocation slip in face-centered cubic metals and alloys. Both aspects determine the details of plastic deformation and, therefore, lead to different results under tribological load. A series of Cu-Mn alloys was investigated in the present investigation, which exhibit wavy slip mode and an almost constant stacking fault energy over a wide solute concentration range. Solid solution strengthening is the main contribution to the hardness in these alloys. The sole impact of changing strength and hardness on the tribological response along with microstructure evolution during tribological load is assessed. After the reciprocating, tribological loading a linear correlation between the wear track width and hardness could be ascertained. Electron microscopy reveals a horizontal discontinuity of the dislocation structure beneath the surface in all alloys at a similar depth. An evaluation of the Hamiltonian elastic stress field model indicates that the depth of the dislocation feature after one sliding pass correlates with the stress distribution as well as the critical stress for dislocation motion. The subsurface microstructure features a transition from the dislocation feature to subgrain formation after about five to ten 2 cycles. Beyond ten cycles, oxide clusters are formed on the sliding surface and the grains elongate in the sliding direction.

Unraveling the Origin of Tribomagnetization in Ferromagnetic Materials

“…Our mechanistic-based model (substituting eq 5 into 4) tells that the development of the depth of the high-ρ GND area is affected by not only ε s but also the wear scar width c. Especially, the increased c leads to the deeper influencing area under sliding by moving the surface dislocations to the deep of the material. This indeed provides experimental evidence to the stress field analysis based on the Hamilton and Goodman elastic model, 40 where the depth of the isostress contours was found to be positively correlated with the wear scar width.…”

“…38 The low shear stress at the interface is not sufficient to drive dislocations into the material. 39,40 However, the dislocations can be transported and multiplied parallel to the sliding direction by following the pin motion. 18,26 The high dislocation density in the localized area close to the surface would result in the formation of a 30 μm refinement layer of grains as illustrated in Figure 4a.…”

Subsurface Microstructural Evolution during Scratch Testing on Bcc Iron

“…This contrast was then referred to as the dislocation trace line (DTL). The occurrence of the DTL, which was also found in arrays of copper alloys and nickel [27,28], was explained through the motion of dislocations in the complex stress field associated with the moving sphere. It was recently observed that this dislocation self-organization is also the location where a localized simple shear of the subsurface material occurs in the sliding direction [24].…”

Extended Shear Deformation of the Immiscible Cu–Nb Alloy Resulting in Nanostructuring and Oxygen Ingress with Enhancement in Mechanical Properties

“…In a tribological setup, the local pressure is relatively low (in the order of MPa), while the repetitive scratching of the surface induces a high strain in the material, which results in microstructural transformation. 5 , 27 − 30 Here, the local pressure, total strain, and deformation rate can be precisely controlled relatively easily. Hence, the tribological setup was used for conducting this study.…”