Ultra-high temperature deformation in TaC and HfC |
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| Authors: | Chase J Smith Morgan A Ross Nicholas De Leon Christopher R Weinberger Gregory B Thompson |
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| Affiliation: | 1. The University of Alabama, Department of Metallurgical and Materials Engineering, 401, 7th Avenue, 285 Hardaway Hall, Tuscaloosa, AL 35487, USA;2. Colorado State University, Department of Mechanical Engineering, 1374 Campus Delivery, Fort Collins, CO 80523-1374, USA;3. Colorado State University, School of Advanced Materials Discovery, Fort Collins, CO 80523-1374, USA |
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| Abstract: | TaC and HfC bars were thermo-mechanically tested up to 2900?°C using a non-contact loading method based on the Lorentz force. It was observed that HfC deflected more than TaC up to 2300?°C, which has been contributed to a difference in grain size facilitating diffusional creep, either Nabarro-Herring or Coble creep. Above 2500?°C, TaC continued to deflect more with temperature whereas HfC showed a reduced deflection. This reduced deflection was found to be an artifact of a preload plastic deformation response. Though both sets of samples were identified to have a prevalence of <110>{110} slip, at elevated temperatures, it appears that mass transport and diffusional creep mechanisms dominate evident by porosity in the grain boundaries. The activation energies of TaC were found to be 946?±?157?kJ/mol (between 2500–2700?°C) and HfC to be 685?±?54?kJ/mol (between 2100–2300?°C). |
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| Keywords: | Transmission electron microscopy (TEM) Transition metal carbides Dislocations Creep TaC HfC |
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