Influences of processing parameters on the microstructure and wear performance of Cr2AlC MAX phase prepared by spark plasma sintering method

In this study, the influences of processing parameters such as milling time of starting materials and spark plasma sintering (SPS) temperature on the microstructural aspects, and tribological and mechanical properties of Cr2AlC MAX phase were investigated. It was found that in the samples milled for 2 h, the increment of SPS temperature from 1000 degrees C to 1300 degrees C, only slightly enhanced the weight percentage of Cr2AlC phase, and the content of this MAX phase was increased from 64.17 wt% at 1000 degrees C to 68.05 wt% at 1300 degrees C. Due to the better wear performance of SPS-processed samples at 1100 degrees C, this temperature was selected as the optimum sintering temperature. According to microstructural studies, 2 h of milling was not enough for reducing the diffusion distance between the particles, and as a consequence, a considerable amount of undesired Cr7C 3 carbide remained in the system. Therefore, to facilitate the interdiffusion process, the milling time was extended to 4 h and 8 h. By increasing milling time up to 8 h, the weight percentage of the carbide phase was considerably decreased, and the content of Cr2AlC phase was increased to the maximum quantity (97.24 wt%). The results of wear tests showed that there is a direct relationship between the content of Cr2AlC phase and wear resistance of samples, and the sample milled for 8 h and SPS-processed at 1100 degrees C, which contains highest MAX phase exhibits the best wear performance among all samples. The microstructural studies from the worn surfaces of prepared samples confirmed the occurrence of oxidation, delamination and adhesion mechanisms during wear processes. (C) 2019 Elsevier B.V. All rights reserved.