Microstructure and Wear Performance of High-Entropy Tribaloy Alloys

The material design concept of high-entropy alloy (HEA) is proposed for Tribaloy alloys. In this research, three HEAs are created by mixing Co-based T-800 and Ni-based T-700 Tribaloy alloys in different ratios and fabricated via spark plasma sintering (SPS) process. The phase transformation behavior of the mixed powders of T-800 and T-700 is investigated with differential scanning calorimetry (DSC) analysis. The microstructures of the SPS specimens and solidified DSC samples of the created HEAs are studied using SEM and XRD, showing that they consist of fcc Co, Mo, and Ni solid solution with minor hcp Co solid solution, various Laves phase, mainly Co 3 Mo 2 Si, CoMoSi, Ni 3 Mo 2 Si, Mo 2 Si, and CrSi 2 , and complex intermetallic compounds. The hardness and dry-sliding wear resistance of the created SPS HEAs are evaluated and compared with the initial alloys (T-800 and T-700). It is shown that the hardness and wear resistance of T-800 are much higher than that of T-700, which is attributed to the excellent properties of element Co; the created HEAs exhibit better hardness and wear performance than T-700 but worse than T-800. The HEA having an equal mixture ratio of T-800 and T-700, with the largest configurational entropy of 1.58R, performs the best in wear resistance among the HEAs.