Thermophysical Properties of α‐Tungsten Carbide

Upper and lower bounds for the thermal expansion of polycrystalline tungsten carbide (α-WC) are predicted at ultrahigh temperatures from low-temperature experimental data. The lower bound is obtained from an α V K T V model, where α V is the volume thermal expansion, K T the isothermal bulk modulus for a randomly oriented polycrystalline sample, and V the molar volume. For many materials, the α V K T V product approaches a constant value that is similar to the specific heat at the highest temperatures. The upper bound uses Griineisen's rule with a constant Gruneisen parameter γ at temperatures >1.3θ D (where θ D is the Debye temperature) and experimental data below that temperature. Literature data for the thermophysical properties of α-WC have been reviewed and used in our α V K T V model to calculate a lower bound for the thermal expansion at temperatures >2θ D and to calculate the temperature dependence of the bulk modulus. The ultrahigh-pressure thermal expansion has been calculated from the lower bound. Model predictions of the thermophysical properties of WC are given for an extended temperature range.

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