ELASTIC PROPERTIES AND THERMAL EXPANSION OF NIOBIUM MONOCARBIDE TO HIGH TEMPERATURES

The temperature dependence of Young's modulus of polycrystalline NbC0.969, with a density of 95.8% of theoretical, follows Wachtman's equation and may be expressed as E = 4.6039 × 1012 -5.7289 × 108 T exp(-200.5/T) dynes/cm2 from 285 ° to 2173 °K. The temperature dependence of the shear modulus is linear and may be expressed as G = 1.9286 × 1012 -2.4848 × 108 T dynes/cm2 from 284 ° to 2173 °K. Above 2173 °K the moduli decrease rapidly, possibly due to viscous grain boundary slip. This temperature corresponds to 0.56 of the absolute melting point maximum for niobium monocarbide. The dilatometric linear thermal expansion was found to be 2.04% from 17 ° to 2447 °C. © 1969.