Tribological Behavior of AlCoCrFeNi(Ti0.5) High Entropy Alloys under Oil and MACs Lubrication

The tribological properties of AlCoCrFeNi and AlCoCrFeNiTi0.5 high entropy alloys under gear oil and multiply alkylated cyclopentanes (MACs) lubrication condition have been studied. The equiaxed crystal structure of AlCoCrFeNi alloy is obtained after heat-treatment. The AlCoCrFeNiTi0.5 alloy keeps dendrite structure. Under the gear oil with good lubrication action, AlCoCrFeNiTi0.5 alloy preserves better tribological properties than AlCoCrFeNi alloy. The delamination and crack behaviors tend to occur in the grain boundary of AlCoCrFeNi alloy and along the interdendrite region of AlCoCrFeNiTi0.5 alloy. Under the MACs with relatively poor lubrication action, the applied load slightly influences the wear behavior of AlCoCrFeNi alloy, but seriously impacts the wear mechanism of AlCoCrFeNiTi0.5 alloy. Compared with AlCoCrFeNi alloy, AlCoCrFeNiTi0.5 alloy keeps better wear-resistance at low applied load of 100 N, but preserves less wear-resistance at high applied load of 200 N.