THERMOPHYSICAL PROPERTY CORRELATIONS FOR THE NIOBIUM-1-PERCENT ZIRCONIUM ALLOY
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Correlations were developed for the temperature dependence of specific heat (cp), enthalpy (h), entropy (s), Gibbs free energy (G), free energy function (FEF), mean coefficient of linear thermal expansion (), density () and lattice parameter (a) of niobium-1% zirconium. The specific heat and thermal expansion correlations were developed as empirical fits to experimental data. The enthalpy, entropy and free energy correlations were derived from the specific heat correlation, and the density and lattice parameter correlations were derived from the thermal expansion correlation. cp = 0.2441 + 5.105 10-5(T) + 2.784 109 T2 exp(- 2.295 104 T) kJ/kg K, h(T) - h(298K) = -75.01 + 0.2441(T) + 2.553 10-5(T)2 + 1.213 105 exp(- 2.295 104 T) kJ/kg, s = 0.2441 In(T) + 5.105 10-5(T) - 0.9947 kJ/kg K, G = 1.2388(T) - 2.552 10-5(T)2 - 0.2441(T) In(T) + 1.213 105 exp(- 2.295 104 T) kJ/kg, FEF = - 1.2388 + 0.2441 In(T) + 2.552 10-5(T) + 75.01 T - 1.213 105 T exp(- 2.295 104 T) kJ/kg K, m = 6.62 + 3.64 10-4(T) + 2.75 10-7(T)2 10-6/K, = 8637 - 0.200(T) kg/m3, a = 3.293 + 2.622 10-5(T) A . The specific heat correlation has a relative standard deviation of 0.98% and is valid over the temperature range 298 to 2700 K. The enthalpy, entropy and free energy correlations have the same temperature range of validity as the specific heat correlation. Statistical methods were employed to determine the propagation of error from the specific heat correlation to estimate the uncertainty associated with each of the derived correlations. The relative standard deviation of the thermal expansion correlation is 0.96% and it has a valid temperature range of 575 to 1627 K. The density and lattice parameter correlations are valid over the temperature range 297 to 1627 K. The propagation of error introduced by the derivation of the density and lattice parameter correlations was calculated in the same manner as for the derived thermodynamic correlations. 1990.
