Jean-Claude Gachon

Thermodynamic investigation of the aluminum-chromium system

In the course of a thorough investigation of the Al-Cr-Nb ternary system, the intermetallic compounds of the Al-Cr system were investigated by direct reaction calorimetry at high temperatures. New enthalpies of formation were determined and compared with literature data. X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), and differential thermal analysis (DTA) were carried out on calorimetric products as well as on heat-treated alloys. A eutectoid decomposition of the Al11Cr2 phase

Calorimetric study of the aluminium-titanium system

\left( {Al_{11} Cr_2 \leftrightarrow Al_7 Cr + Al_4 Cr} \right)

A thermodynamic study of the Al–Cr–Nb ternary system

was discovered. The eutectic nature of the equilibrium involving Al7Cr with Al solid solution was verified and this contradicts the published phase diagram. The hexagonal (Al4Mn structure type) of Al4Cr was confirmed.

Calorimetric study and optimization of the ruthenium-zirconium phase diagram

Abstract The enthalpies of formation of the intermetallic compounds of the Al–Nb system were measured by direct reaction calorimetry at high temperatures. Results were compared with the available experimental values based on calorimetric and vapor pressure measurements and computed values based on the semiempirical model of Miedema. X-ray Powder Diffraction and Electron Microprobe Analysis techniques were used to verify the crystal structures and compositions of the phases under scrutiny.

New results about the osmium-zirconium system

Abstract The intermetallic compounds of the Al–Ti system were investigated by direct reaction calorimetry at high temperatures. New enthalpies of formation were determined and compared with the available experimental values based on calorimetric measurements and with the predicted values from Miedema’s semi-empirical model. X-ray powder diffraction (XRD) and electron probe microanalysis (EPMA) were used to check the crystal structure and the homogeneity of the calorimetric products.

Calorimetric study of the Hf–Os and Os–Ti systems

A new assessment of the Nb-Sn system is proposed considering the Nb3Sn phase stable down below room temperature. The Gibbs energy of formation of the solution and compound phases in the Nb-Sn syste ...

Optimization of the binary Ce–Ru system

Abstract The Al–Cr–Nb isothermal section at 1000°C was studied by thermal analysis, X-ray diffraction and electron microprobe analysis. The enthalpies of formation of the different compounds were determined by direct reaction calorimetry. Results are presented and discussed.

Enthalpies of formation of the AlNb intermetallic compounds

Abstract The Ru-Zr system has been investigated by direct reaction calorimetry at high temperature. The enthalpies of formation of both intermetallic compounds have been measured: ΔfH(Ru0.50Zr0.50; 1753 K) = −55800 ± 2300 J/mol; and ΔfH(Ru0.67Zr0.33; 1743 K) = −32000 ± 900 J/mol. These results, together with the available experimental phase diagram data have been used to obtain a thermodynamic optimization of this system. Copyright