Enthalpy of formation of UZr2 by calorimetry

Ab Initio Enhanced calphad Modeling of Actinide-Rich Nuclear Fuels

“…20, the enthalpy of formation of the δ phase at 298 K is calculated in this work in order to compare with the previous assessments [77,79], ab initio calculations [105] as well as experiments by Nagarajan et al [44]. As noted in section 3.2., there are two choices of the thermodynamic model for the δ phase in the previous assessments.…”

“…The deviation is over 0.8 eV/atom for cohesive energy of αU and mostly over 0.05 eV/atom for enthalpy of formation of other phases (The values are given in Table 1, and their statistics in Table 2). Particularly, for δ(U,Zr) which is stable at low temperature and therefore should have negative enthalpy of formation at 0 K, DFT calculation gives a considerably positive enthalpy of formation, 0.043 eV/atom, while CALPHAD models gave -0.013 [6], -0.045 [42] and 0 eV/atom [43] and an available calorimetry experiment [44] gave -0.04±0.11 eV/atom (-4.0±10.1 kJ/mole). Our DFT result is, however significantly different from Landa et al's DFT result of -0.065 eV/atom [39], which is quite negative.…”

“…[52]; CALPHAD models are from Xiong et al [6], Kurata [42], and Chevalier et al [43] which all use the same SGTE data for pure elements [53] and give the same enthalpy of formation for βU and γU. [44]; the very large error bar is not plotted in c). CALPHAD models are from Xiong et al [6], Kurata [42], and Chevalier et al [43].…”

“…Enthalpy of formation for U-Zr alloy: a) α(U) (6.3 at.% Zr), b) β(U) (3.3 at.% Zr), c) δ(U,Zr) (66.7 at.% Zr) and d) α(Zr) (93.8 at.% Zr), The vertical dash reference line is at U eff =1.24 eV. Experimental enthalpy of formation for δ(U,Zr) -0.04±0.11 eV/atom is from Nagarajan et al [44]; the very large error bar is not plotted in c). CALPHAD models are from Xiong et al [6], Kurata[42], and Chevalier et al [43] Figure 4.…”

“…Comparison of heat capacity of the U-Zr alloys between CALPHAD modelprediction [77,79] and experimental data [92][93][94]103]. (a) Summary of the experimental information provided by different research groups [92][93][94]103] [105], CALPHAD [77,79] and experimental data [44]. In CALPHAD modeling from the present work, case 1A is using the energy difference of (Zr) between hcp and δ structures as 1000 J/mol for model 1 (Zr)1(U,Zr)2, while case 1B is using 527.…”