Tribological Properties Of Al_0.6CoCrFeNi High-Entropy Alloy In Different Conditions

In recent years,high-entropy alloys have attracted the attention of a large number of scholars due to their simple structure and excellent performance.However,most of their research points focus on optimizing the microstructure of high-entropy alloys and their mechanical and mechanical properties.Little attention has been paid to the surface properties of high-entropy alloys,especially friction and wear properties.In this paper,the friction and wear properties of Al_0.6CoCrFeNi high-entropy alloy in various environments are studied.The as-cast high-entropy alloy Al_0.6CoCrFeNi was prepared by vacuum arc melting method,and a set of samples was annealed to study its high temperature and normal temperature performance.The friction and wear test was carried out at room temperature using a ball-type high-speed reciprocating wear test device?MFT-R4000?.The experimental environment was dry,deionized water,acid rain,and simulated seawater.The reciprocating frequencies are 2,3,4,and 5 Hz,respectively.The high temperature test was carried out under dry conditions using a high temperature ball disc type friction and wear tester?HT-4001?.The temperatures were set to 20,100,200,300,400,500 and 600?,respectively.In addition,GCr15 was used as a comparative material.During the experiment,atomic force microscopy?AFM?,Vickers hardness tester,XRD,scanning electron microscopy?SEM?analyzer with EDS,3D white light diffractometer,XPS and other instruments were used to analyze the surface properties,microstructure and surface morphology of the alloy.The research results show that:?1?The as-cast high-entropy alloy Al_0.6CoCrFeNi has a typical dendritic phase and interdendritic phase.It consists of a simple FCC and BCC/B2 phase with a Vickers hardness of 278 HV.After heat treatment,Al_0.6CoCrFeNi still has a typical dendritic phase and interdendritic phase,but a new phase is formed.The phase structure is FCC+B2+?phase,and its Vickers hardness rises to 480 HV.And the precipitated?phase provides a more stable high temperature structure and higher strength for Al_0.6CoCrFeNi.?2?At room temperature,the wear rate and friction coefficient of the alloy decrease first and then increase with the increase of frequency.In addition,the wear rate of the as-cast alloy is higher than that of the liquid environment under dry conditions.The lowest wear rate was reached in seawater.?3?The main wear mechanisms of as-cast alloys in dry air are severe abrasive wear,delamination wear and oxidative wear;the main wear mechanism in deionized water is abrasive wear with delamination and slight adhesive wear.The wear mechanisms in acid rain and seawater are mainly abrasive wear,oxidative wear,adhesive wear and corrosion wear.In addition,the corrosion resistance of Al_0.6CoCrFeNi in seawater is better than that in acid rain.?4?The oxide films of Al_0.6CoCrFeNi HEAs are mainly Al₂O₃,Cr₂O₃ and Fe₂O₃,and the volume fraction tends to be stable at 400?.In addition,its antioxidant and high temperature softening properties are far superior to GCr15.?5?With the increase of temperature,the friction coefficient of Al_0.6CoCrFeNi gradually decreases and is more stable,which is attributed to the oxide film formed at high temperature.In addition,when the temperature is lower than 200?,the wear rate of Al_0.6CoCrFeNi is higher than that of GCr15;when it is above 300?,the growth rate of wear rate is very slow and tends to a stable value.However,as the temperature increases,the wear rate of GCr15 increases rapidly.?6?Oxidation occurs in all temperature ranges.At room temperature and 100?,the dominant wear mechanism is abrasive wear.At 200?,the main wear mechanism changes from abrasive wear to delamination and plastic deformation.Above 300?,the wear mechanism is mainly oxidative wear and delamination wear.