Experimental investigation of friction behaviors for CrCoNi medium entropy alloy in reciprocating sliding.

Medium/high entropy alloys have some excellent properties, such as high strength, high plasticity, high toughness, high wear resistance, etc., which are better than those of traditional metal alloys. The mechanical properties of medium/high entropy alloys have always been the focus of academic research, but research on their interface mechanical behaviors is still missing. In this paper, we have designed a fretting friction and wear testing system, whose accuracy has been verified. A series of friction experiments have been carried out on the medium entropy alloy–steel friction pair. The friction responses have been investigated, and the factors affecting the friction coefficient have been revealed. Results show that the friction coefficient increases with the increase in the maximum horizontal displacement and decreases with the increase in the normal pressure. The sliding velocity and the normal load together affect the friction coefficient between the friction pairs. Compared with the commonly used titanium alloy and nickel alloy, the friction coefficient between the medium entropy alloy–steel friction pair is smaller during the fretting cycle process. Despite the experimental results, a theoretical model is also proposed to qualitatively explain the corresponding experimental phenomena. Our research sheds light on revealing the interfacial mechanical properties of the medium entropy alloy and provides a basis for tribological design and its internal mechanism. [ABSTRACT FROM AUTHOR]