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The effect of submicron grain size on thermal stability and mechanical properties of high-entropy carbide ceramics |
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| Authors: | Fei Wang Xiang Zhang Xueliang Yan Yongfeng Lu Michael Nastasi Yan Chen Bai Cui |
| Affiliation: | 1. Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE, USA;2. Department of Electrical & Computer Engineering, University of Nebraska–Lincoln, Lincoln, NE, USA;3. Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE, USA
Nebraska Center for Energy Sciences Research, University of Nebraska–Lincoln, Lincoln, NE, USA Nebraska Center for Materials and Nanoscience, University of Nebraska–Lincoln, Lincoln, NE, USA;4. Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA |
| Abstract: | (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)C high-entropy ceramics (HEC) with a submicron grain size of 400 to 600 nm were fabricated by spark plasma sintering using a two-step sintering process. Both X-ray and neutron diffractions confirmed the formation of single-phase with rock salt structure in the as-fabricated (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)C samples. The effect of submicron grain size on the thermal stability and mechanical properties of HEC was investigated. The grain growth kinetics in the fine-grained HEC was small at 1300 and 1600°C, suggesting high thermal stability that was possibly related to the compositional complexity and sluggish diffusion in HEC. Compared to the coarse-grain HEC with a grain size of 16.5 µm, the bending strength and fracture toughness of fine-grained HEC were 25% and 20% higher respectively. The improvement of mechanical properties in fine-grained HEC may be attributed to micromechanistic mechanisms such as crack deflection. |
| Keywords: | grain size high-entropy ceramics mechanical properties spark plasma sintering thermal stability |