Research to Determine the Mechanisms Controlling the Brittle-Ductile Behavior of Refractory Cubic Carbides

摘要

Plastic flow at high temperatures in single crystals of the transition metal monocarbides has been studied by determining the influence of temperature, strain rate, surface condition, and carbon/metal ratio on the compressive yield stress. Yielding in the carbides is apparently controlled by lattice friction. A study of the influence of carbon vacancies on the resistivity, P, and Hall coefficient of TiC has shown that the added resistivity/atomic per cent vacancies is 16 milliohm cm and that the value of P for stoichiometric TiC is 70 = 10 milliohm cm. Literature values for magnetic susceptibility and Hall coefficient of TiC, and new measurements of its Seebeck coefficient, are discussed in terms of a plausible band structure. The possibility of a transfer of electrons from carbon to titanium atoms is suggested, and the implications of the resulting ionic character are discussed for the elastic moduli and the cohesive energy. (Author)