Sliding wear behavior of fully nanotwinned Cu alloys

Abstract

Highly nanotwinned (NT) metals have advantages such as high strength, good ductility, favorable corrosion resistance, and thermal stability. It has been demonstrated that the introduction of high density NT microstructures can enhance the tribological properties of metals. However, the influence of the microstructure and the composition of NT alloys on the tribological behavior are not clear. In this work, the sliding wear behavior of fully NT materials, specifically Cu-Al and Cu-Ni alloys, are studied by a nanoscratch technique using a nanoindenter. The effects of microstructure and chemical composition on the wear properties are also studied. The results show that the chemical composition has an obvious influence on the wear resistance and microstructural deformation. For NT Cu-Al alloys, the hardness and sliding wear resistance improve with increased Al content from Cu-2wt.%Al to Cu-6wt.%Al. NT Cu-10wt.%Ni alloy shows even better wear resistance than Cu-6wt.%Al. The microstructural analysis shows that NT Cu alloys with higher wear resistance correspond to a smaller deformation-affected zone. The improvement of sliding wear properties of Cu-Al alloys with higher Al content may be ascribed to their decreased stacking fault energy. NT Cu-Ni alloy shows better wear resistance than Cu-Al alloy, this may be related to the formation of intermetallic compounds in Cu-Al system. This study broadens the knowledge about tribological properties of NT materials and provides a potential method to optimize their sliding wear resistance by altering the chemical composition of NT Cu alloys.

Microstructures, mechanical properties, and grease-lubricated sliding wear behavior of Cu-15Ni-8Sn-0.8Nb alloy with high strength and toughness

“…In general, the deformation inhomogeneity and stress concentration are both small when the grains are fine, increasing the difficulty of cracking the alloy. Moreover, a large number of twists at the grain boundaries in the fine grains will be unfavorable to the propagation of cracks, making the grains bear a large plastic deformation before fracture [31,32]. Therefore, the addition of Nb realizes simultaneous improvements in the strength and toughness of Cu-15Ni-8Sn alloy through refining the grains.…”

A low-to-high friction transition in gradient nano-grained Cu and Cu-Ag alloys

“…Usually, it is intractable to preserve or prolong the intrinsic low friction state of metals during sliding, and the consequent high friction stage inevitably reduces the energy efficiency and makes these materials unusable in tribological applications. Among the reasons for the swift low-to-high friction transition, sliding-induced shear instability near the surface is the primary factor that triggers surface roughening [3,4] in the initial stage, distinct microstructure discontinuity from the underlying bulk metallic material [5][6][7][8][9], and subsequent subsurface cracking and delamination under tribological loading [10,11]. For instance, there is a clear correlation between the friction transition and the increasing surface roughness in a tungsten-carbon tribo-system sliding for an initial 100 cycles [12].…”

Multiscale frictional behaviors of sp2 nanocrystallited carbon films with different ion irradiation densities

“…Therefore, a transfer layer is required to achieve a low friction coefficient and prominent mechanical behaviors to ensure suitable contact pressure at the macroscale. For tribological applications at the microscale, the mechanism of low friction coefficient is to reduce the overall strength of the contact interface [19][20][21][22][23][24][25]. Good mechanical properties contribute to nanoscratch resistance [20]; for example, the hardness prevents scratching and elasticity helps the film recover from deformation [21,22].…”

“…For tribological applications at the microscale, the mechanism of low friction coefficient is to reduce the overall strength of the contact interface [19][20][21][22][23][24][25]. Good mechanical properties contribute to nanoscratch resistance [20]; for example, the hardness prevents scratching and elasticity helps the film recover from deformation [21,22]. Low surface roughness also plays an indispensable role in achieving low and stable friction [23,24], and the ratio of roughness to the penetration depth during a nanoscratch test had a significant effect on the friction coefficient [25].…”