Effect Of Surface Texturing On Tribological Behavior Of CoCrNi And CoCrFeMnNi Alloys

As a new type of alloy with excellent properties and wide potential applications,the research on tribological behavior of high entropy alloys(HEAs)has been a hot topic.At present,the HEAs mainly as substrate or coating tribological behavior,while few researches are available in the literatures of the combined with surface treatment technology.At the same time,surface texturing treatment technology in improving the tribological performance has a significant effect on the material surface.Therefore,CoCrFeMnNi high entropy alloy with good mechanical properties was applied as the investigate object in the work,and compared with CoCrNi medium entropy alloy,and the influence of surface texturing on the tribological behavior of CoCrNi and CoCrFeMnNi alloys were explored.In this work,the laser processing technology was applied in the CoCrNi medium entropy alloy and CoCrFeMnNi high entropy alloy surfaces to fabricated dimple-shape texture of the different process parameters.The effect of different process parameters of surface texturing on mass loss of two alloys was evaluated by using orthogonal experimental design method.The materials characterizations of the before and after treated two alloys was analyzed.The tribological behavior of substrate and surface textured two alloys was explored under the dry friction condition.The main research contents and results are follows:(1)The combination of different process parameters of surface texturing was arranged by using orthogonal experimental design method and the effect of texture shape,texture area as well as texture space on mass lass of CoCrNi and CoCrFeMnNi alloys was investigated.While the optimal process parameters for two alloys:texture shape was square,texture area was 70686?m²,texture interval was 1200?m.In addition,CoCrNi and CoCrFeMnNi alloys were face-centered cubic solid solutions with a single FCC phase,with the lattice constants of?3.561(?)and?3.592(?),respectively.And the microhardness of CoCrNi and CoCrFeMnNi alloys substrate was 268.66 HV_0.05and 204.38 HV_0.05,respectively,while the microhardness of the alloy substrates after surface texturing treatment was increased slightly by about 11.63%and 11.25%,respectively,which was mainly related to the mechanism of laser ablation processing technology.(2)Under dry friction condition,the contrast samples of the different parameters treatment indicated slight high friction coefficient than those of CoCrNi and CoCrFeMnNi substrates as they was sliding against Si₃N₄ ceramic ball,which showed the dimples texture no friction-reduction effect,which main related to the surface roughness increase after surface texturing treatment.However,the mass loss and specific wear rate of the treated contrast samples were lower than those of CoCrNi and CoCrFeMnNi substrates,which exhibited the better wear resistance.Among them,the mass loss and specific wear rate of CoCrNi medium entropy alloy after surface texturing treatment were the least reduced,reaching 34.46%and10.49%,respectively,while the mass loss and specific wear rate of CoCrFeMnNi high entropy alloy after surface texturing treatment were the least reduced,reaching 28.16%and13.97%,respectively,which was main related to the mechanism of action of surface texturing.Specifically,the existence of dimples texture played an important role in capturing wear debris and reducing the contact area under dry friction condition,therefore effectively reducing the wear damage of CoCrNi and CoCrFeMnNi alloys surface.(3)Under dry friction condition,the surface appeared continuous wear tracks when the CoCrNi and CoCrFeMnNi alloys were sliding against Si₃N₄ ceramic ball,but the surface of the treated samples did not existence continuous wear tracks,which was attributed to the existence of dimple texture to break the continuity of wear tracks.Moreover,under dry friction condition,the wear mechanism of CoCrNi and CoCrFeMnNi substrates and treated contrast samples was abrasive wear,adhesive wear,fracture wear and oxidation wear.However,the wear damage degree of the two alloys was different,and the wear damage degree of the treated samples was lower than that of the substrates.In conclusion,laser processing technology had a slightly positive effect on improving the mechanical properties for CoCrNi and CoCrFeMnNi alloys,and the surface texturing had a significant positive effect on enhancing the wear resistance of CoCrNi and CoCrFeMnNi alloys.