Thermodynamic properties of molybdenum borides at temperatures above 300 K

Bolgar, A. S.; Blinder, A. V.; Serbova, M. I.

doi:10.1007/bf00793382

Cited by 7 publications

(9 citation statements)

References 2 publications

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“…3, where a good agreement between the experimental and calculated values can be observed. The calculated enthalpy differences, H(T ) À H(298), for the phases Nb 3 B 2 , NbB, Nb 3 B 4 and NbB 2 reproduce well the values measured by Bolgar et al [20], as shown in Fig. 4.…”

Section: Stoichiometric Phasessupporting

confidence: 78%

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Thermodynamic modeling of the Nb–B system

et al. 2007

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In the present work, the NbeB binary system was thermodynamically optimized. The stable phases in this system are BCC (niobium), Nb 3 B 2 , NbB, Nb 3 B 4 , Nb 5 B 6 , NbB 2 , B (boron) and liquid L. The borides Nb 3 B 2 , NbB, Nb 3 B 4 and Nb 5 B 6 and the B (boron) were modeled as stoichiometric phases and the liquid L, BCC (niobium) and NbB 2 as solutions, using the sublattices model, with their excess terms described by the RedlicheKister polynomials. The Gibbs energy coefficients were optimized based on the experimental values of enthalpy of formation, low temperature specific heat, liquidus temperatures and temperatures of invariant transformations. The calculated NbeB diagram reproduces well the experimental values from the literature.

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Section: Stoichiometric Phasessupporting

confidence: 78%

“…The thermodynamic data available for this system are (i) the entropy of NbB 2 [13], Nb 3 B 2 , NbB and Nb 3 B 4 phases [14]; (ii) the enthalpy of formation of NbB 2 [15e19]; and (iii) the temperature dependence of the enthalpy, H(T ) À H(298 K), for the phases Nb 3 B 2 , NbB, Nb 3 B 4 and NbB 2 in the 1200e2350 K range [20].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic modeling of the Nb–B system

et al. 2007

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“…The heat enthalpy (H 0 τ − H 0 298 ) and entropy values for MoB were taken from the continuous functions provided by Bolgar et al [41], and H 0 f,298,MoB = −103.9 kJ mol −1 is the value reported by Lavut et al [42]. The thermodynamic values for Al were interpolated from the Joint-Army-Navy-Air Force (JANAF) tables [43].…”

Section: Heat Capacity and Thermodynamic Propertiesmentioning

confidence: 99%

“…(iv) A nominal uncertainty of 1.0% was assumed for the values taken from Bolgar et al [41] and the JANAF tables [43].…”

Section: Heat Capacity and Thermodynamic Propertiesmentioning

confidence: 99%

Elastic properties, thermal stability, and thermodynamic parameters of MoAlB

et al. 2017

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MoAlB is the first and, so far, the only transition-metal boride that forms alumina when heated in air and is thus potentially useful for high-temperature applications. Herein, the thermal stability in argon and vacuum atmospheres and the thermodynamic parameters of bulk polycrystalline MoAlB were investigated experimentally. At temperatures above 1708 K, in vacuum and inert atmospheres, this compound incongruently melts into the binary MoB and liquid aluminum metal as confirmed by differential thermal analysis, quenching experiments, x-ray diffraction, and scanning electron microscopy. Making use of that information together with heat-capacity measurements in the 4-1000-K temperature range-successfully modeled as the sum of lattice, electronic, and dilation contributions-the standard enthalpy, entropy, and free energy of formation are computed and reported for the full temperature range. The standard enthalpy of formation of MoAlB at 298 K was found to be −132 ± 3.2 kJ/mol. Lastly, the thermal conductivity values are computed and modeled using a variation of the Slack model in the 300-1600-K temperature range.

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“…Concerning the thermodynamic properties of B-Nb alloys, the majority of experimental investigations deal with determination of the enthalpy change of different borides upon heating [38,39]. Using these data the heat capacity of Nb 3 B 2 , Nb 3 B 4 , NbB 0.99 and NbB 1.96 borides were evaluated as a function of temperature [39,40].…”

Section: The Binary System B-nbmentioning

confidence: 99%