Plastic flow and dislocation structures in tantalum carbide: Deformation at low and intermediate homologous temperatures

• Published in: Acta metallurgica et materialia Vol. 42; no. 7; pp. 2291 - 2301
• Main Authors: Kim, C., Gottstein, G., Grummon, D.S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 01.07.1994
• Subjects: 360202 - Ceramics, Cermets, & Refractories- Structure & Phase Studies; 360203 - Ceramics, Cermets, & Refractories- Mechanical Properties; CARBIDES; CARBON COMPOUNDS; CREEP; CRYSTAL DEFECTS; CRYSTAL STRUCTURE; DATA; DEFORMATION; DISLOCATIONS; EXPERIMENTAL DATA; INFORMATION; LINE DEFECTS; MATERIALS SCIENCE; MECHANICAL PROPERTIES; MICROSTRUCTURE; NUMERICAL DATA; PLASTICITY; REFRACTORY METAL COMPOUNDS; TANTALUM CARBIDES; TANTALUM COMPOUNDS; TEMPERATURE RANGE; TEMPERATURE RANGE 0273-0400 K; TRANSITION ELEMENT COMPOUNDS
• ISSN: 0956-7151; 1873-2879
• DOI: 10.1016/0956-7151(94)90308-5

Dislocation structures and plastic flow in TaC 0.99 have been studied in material deformed by microindentation at 20°C, and in specimens crept at temperatures between 0.37 and 0.43 T m (1300–1500°C). Extensive local plastic deformation occurred during indentation, accomplished mainly by the motion of a 2 edge dislocations gliding on {111}. The resulting defect structure consisted primarily of long screw dislocations, suggesting a relatively high mobility for edge segments and a large Peierls stress for screw dislocation motion. This {111} slip system also operated in specimens crept at 0.37–0.43 T m. Thermal activation apparently increased the mobility of screw segments, resulting in substructures containing mixed dislocations with no preferred orientation. Microstructural observations, and analysis of kinetic data for power-law creep, suggest that intermediate temperature creep deformation of TaC 0.99 occurs mainly by climb-controlled grain boundary sliding with severely limited intergranular accommodation.