Influence of TiC on the microstructure and wear resistance of AlCoCrFeNi2.1 eutectic high-entropy alloy composite coatings by laser cladding
Ran Ji, Pengfei Jiang, Chao Huo, Minghao Nie, Jinze Teng, Xue Han, Daitong Yu, Tailin Yue, Zhihui Zhang
Abstract
With the aim of enhancing the mechanical properties and wear resistance of eutectic high-entropy alloys (EHEAs) by laser cladding (LC), ceramic reinforcement phases are introduced into the alloy system to achieve the microstructural design of the materials. It is essential to determine the appropriate content of ceramic particles to be added to the matrix alloy. In order to explore the appropriate concentration window, the fabrication of EHEA coatings of AlCoCrFeNi 2.1 with different TiC reinforcement contents on 316L stainless steel by LC has been achieved. The influences of TiC addition amount on the constituent phases, microstructure, elements composition, microhardness and wear behavior of the AlCoCrFeNi 2.1 - x TiC ( x =0, 3, 5, 7 wt%) composite coatings were analyzed. The results show that the EHEA composite coatings are constituted of face-centered cubic (FCC), body-centered cubic (BCC) and TiC phases. With the increase of TiC content in the EHEA composite coatings, the microstructure of the composite coatings is continuously refined and the TiC dendrites gradually increase. The AlCoCrFeNi 2.1 -3wt%TiC composite coating exhibits the highest microhardness of 378.2 HV 0.3 among all the coatings. It also demonstrates the best wear resistance, with an average coefficient of friction (COF) of 0.829 and a wear rate of 6.29×10 -4 mm 3 /Nm under a load of 20 N, and an average COF of 0.701 and a wear rate of 4.16×10 -4 mm 3 /Nm under a load of 40 N. Moreover, when the addition of TiC in the composite coatings reaches 5wt% and 7wt%, the average microhardness and wear behavior of the composite coatings decrease compared to the coating with no TiC added. The wear mechanism of the 3wt% TiC coating primarily manifests as adhesive wear and oxidative wear under a load of 20 N, while it primarily manifests as abrasive wear and oxidative wear under a load of 40 N. The research results are of great significance to extend the service life of EHEA composite coatings under extreme working conditions.