Ultra-high temperature deformation in TaC and HfC. Issue 16 (December 2018)

• Record Type: Journal Article
• Authors: Smith, Chase J.; Ross, Morgan A.; De Leon, Nicholas; Weinberger, Christopher R.; Thompson, Gregory B.
• Is Part Of: Journal of the European Ceramic Society. Volume 38:Issue 16(2018)
• Page Start: 5319
• Page End: 5332
• Publication Date: 2018-12
• Subjects: Transmission electron microscopy (TEM) -- Transition metal carbides -- Dislocations -- Creep -- TaC -- HfC; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2018.07.017
• Languages: English
• ISSNs: 0955-2219

Abstract

Highlights: Thermo-mechanical testing up to 2900°C. <110>{110} primary slip in TaC and HfC. Experimentally demonstrated grain size controls ultra-high temperature deflection more than ease of available slip systems. 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).