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

• Published in: Journal of alloys and compounds Vol. 815; p. 152345
• Main Authors: Shamsipoor, A., Farvizi, M., Razavi, M., Keyvani, A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 30-01-2020; Elsevier BV
• Subjects: Carbides; Cr2AlC MAX phase; Hardness; Interdiffusion; Mechanical properties; Microstructure; Oxidation; Plasma sintering; Process parameters; Spark plasma sintering; Spark Plasma Sintering (SPS); Tribology; Wear; Wear mechanisms; Wear resistance; Weight; Cr2AlC MAX phase; Spark Plasma Sintering (SPS); Microstructure; Hardness; Wear
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.152345

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 °C to 1300 °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 °C to 68.05 wt% at 1300 °C. Due to the better wear performance of SPS-processed samples at 1100 °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 Cr7C3 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 °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.
•High-purity Cr2AlC MAX phase can be produced by a combination of MA-SPS methods.•Cr7C3 phase has been evolved as the impurity phase in the SPS-processed samples.•Increment of milling times has a positive impact on the purity of Cr2AlC MAX phase.•Milling for 8 h and SPS process at 1100 °C led to the highest purity of Cr2AlC phase.•Higher the content of Cr2AlC phase, better the wear resistance of samples.