Wang Changzhen

Interaction coefficients in Fe-C-Ti-i (i = Si, Cr, AI, Ni) systems

Ever since Schroeder and Chipman[10] initiated the application of the silver bath iso-activity method to the study of activity interaction coefficients of components in iron alloys, the method was only applied to some ternary systems in which only one component dissolves in both liquid iron and liquid silver. The authors of the present work proposed a method which enables the silver bath iso-activity method to be utilized to study the activity interaction coefficients of two components simultaneously dissolvable in both liquid iron and liquid silver by establishing an iso-i-j-activity state for several Fe-C-i-j quarternary samples through a common silver bath. This new “quarternary silver bath iso-activity method” was applied to quarternary Fe-C-Ti-i (i = Si,Cr, Al,Ni) melts at 1600 °C and estimated the activity interaction coefficients as follows: εTi¡ = 7.96, ρTi¡ = −6.88, ρsiTi = 0.51, ρTiTi,si = −2.27, ρTiTi,si = −5.66 εTiŗ = 3.46, ρTiŗ = 10.43, ρTiCr,Ti = 17.40 εTiAl = 0.93, ρTiŗ = 10.22, ρTiAl,Ti = 25.11 εTiNi = 2.49, ρTiNi = 9.33, ρTiNi,Ti = 16.37

Interaction coefficients in the iron-carbon-titanium and titanium-silver systems

A liquid Fe-C-Ti system was studied by establishing an iso-titanium-activity state for ternary samples at 1600 °C through the medium of a bath of liquid silver which permits diffusion of titanium only. From the two iso-titanium-activity lines obtained, the self-interaction coefficients of titanium and interaction coefficients of carbon on titanium in liquid iron were estimated:εTiTi = 4.67, ρTiTi = 0.32, εTiC = −11.94, ρTiC = −4.52, ρTiTi,C = −9.96 An experimental study has been made of the distribution of titanium between liquid silver and liquid iron at 1600 °C. By the use of the interaction coefficients of titanium and rTio in liquid iron, the thermodynamic parameters of titanium in liquid silver were determined asrTioAg = 2.44 X 10−3, (εTiTiAg = −6.17, (ρTiTi)Ag = −16.3

Thermodynamic properties of doped lanthanum manganites

The thermodynamic properties of the perovskite compounds La[sub 0.8]Sr[sub 0.2]MnO[sub 3] (LSM), La[sub 0.9]Na[sub 0.1]MnO[sub 3] (LNM), and LaMnO[sub 3] (LM) were studied by use of the solid electrolyte galvanic cell method at 1,000 C, 1,050 C, and 1,100 C. Two samples of each compound were investigated as well as decomposed samples of LSM and LNM. The cell assembly was constructed by means of eight small stabilized zirconia tubes and a common Ni/NiO reference electrode. The equilibrium partial pressures of the samples were calculated form the measured EMF values. The results reveal that the equilibrium pO[sub 2] of LM appears to be one or two orders of magnitude lower than that of LSM and LNM, respectively, which means that LM is more stable than the doped perovskites. The variation in the standard free energy with temperature for the perovskite decomposition reaction was calculated from the pO[sub 2] equilibrium values, i.e. [Delta]G[degree]d (LSM) = 140.86 [minus] 0.05199T kJ/mole and [Delta]G[degree]d (LNM) = 106.06 [minus] 0.02572T kJ/mole. On the basis of the above equations, the reaction enthalpy and entropy changes were calculated. Perovskite oxides have received considerable attention in recent years for their use as cathodes in solid oxide fuel cells.

Thermodynamic properties of the intermetallic compounds Re2Fe14B (Re≡La, Ce, Y)

Abstract The intermetallic compounds Re 2 Fe 14 B (Re La, Ce, Y) with tetragonal structure were prepared. The chemical thermodynamic properties of the compounds were studied by using a galvanic cell with a CaF 2 single crystal as a solid electrolyte having an Re/ReF 3 reference electrode in the temperature range 900–1020 K.

Thermodynamic studies of YFe12−xVx and SmFe12−xVx alloys

Abstract The Invar alloys of YFe12−xVx (x=1.6, 2.0, 2.4, 2.8, 3.2) and SmFe12−xVx (x=2.4, 2.8) were prepared. The activity and the relative partial molar Gibbs free energy of the yttrium and samarium in the alloys were determined by the e.m.f. method using a single crystal of CaF2 as a solid electrolyte at temperatures of 920–1020 K and 900–1000 K respectively.