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A. Dębski

Abstract

Li-Si, Ag-Ca, B-Li, Ca-Li and Al-Li belong to the group of application alloys. The Entall database includes experimental data on the enthalpy of formation of the intermetallic phases belonging to the mentioned systems, as well as software for the calculation of other thermodynamic functions. The presented Entall database is the first proposal of a thermodynamic property data, which will be gradually extended by new metal alloy systems. It is a free database, available at www.entall.imim.pl.

Open access

A. Dębski

Abstract

The direct reaction calorimetric method was used for the determination of the formation enthalpy of alloys which concentrations correspond to the: Ga7Li2, Ga9Li5, GaLi, Ga4Li5, Ga2Li3, and GaLi2 intermetallic phases. The obtained experimental values of the formation enthalpy were: −18.1 ±0.8 kJ/mol at., −26.5 ±0.3 kJ/mol at., −34.7 ±0.3 kJ/mol at., −33.5 ±0.5 kJ/mol at., −32.8 ±0.3 kJ/mol at. and −24.6 ±1.4 kJ/mol at., respectively. After the calorimetric measurements, all the samples were checked by way of X-ray diffraction investigations to confirm the structure of the measured alloys. All the measured values of the formation enthalpy of the Ga-Li alloys were compared with literature data and the data calculated with use of the Miedema model.

Open access

W. Gąsior and A. Dębski

The solution calorimetric method was used for the measurement of the formation enthalpy of the binary FeTi and Fe2Ti intermetallic phases and of the FeNiTi2 phase from the region of the ternary B2 one.

The FeNi and FeNiTi2 phases were prepared by levitation melting and the Fe2Ti phase - by melting the metals in a glove-box under high purity argon. The alloys obtained were identified by the X-ray diffraction analysis. The structural study of the alloys with the composition equal to the FeTi and Fe2Ti phase confirmed the mentioned phases mainly in the samples. In the case of the ternary alloy of the composition of the FeNiTi2 phase, a slight amount of iron was also found. The obtained values of the formation enthalpy equal as follows: -27.2±1.3 kJ/mole of atoms, -22.5±1.4 kJ/mole of atoms and -34.2±1.3 kJ/mole of atoms for the Fe2Ti, FeTi and FeNiTi2 phase, respectively.

Open access

A. Debski, R. Debski and W. Gasior

Abstract

This paper presents a new version of the Entall database of the thermodynamic properties of metals and their alloys. The changes are related to the thermodynamic data of new binary and ternary systems as well as the integration of the database with an application for the modeling of the formation enthalpies of intermetallic phases with the use of the Miedema model. Using this tool, calculations of the enthalpies of formation of 38 intermetallic phases from 12 binary systems were performed and a comparative analysis conducted. The results of the analysis clearly showed a weak correlation between the model and experimental data. To improve this correlation, an intermediate method of proportional change was proposed, on the basis of the measurement of the enthalpy of formation for one of the phases. The values for the other phases obtained from this indirect method should not deviate much from the experimental ones provided that before the measurements (dissolving or pulping) or after them (direct synthesis), the phase being examined should undergo structural tests, in order to confirm its dominating amount in the samples.

Open access

W. Gąsior, A. Dębski and R. Major

Abstract

The formation enthalpy of the BLi (B48Li52) intermetallic phase was measured with the use of the water reaction and the direct reaction calorimetric method. The phase was prepared of weighed amounts of B and Li in a glove-box filled with high purity argon. The BLi phase was confirmed with using the X-ray diffraction investigations. The experiments were carried out with the use of a water reaction calorimeter (water reaction calorimetric technique) at 25°C (298 K) in air, as well as a direct reaction calorimeter at 752°C in high purity argon. The formation enthalpy value obtained for the BLi phase in the case of the water reaction calorimetric method equaled -30.3±2.2 kJ/mole of atoms and in the case of the direct synthesis technique - 29.4±2.0 kJ/mole of atoms.

Open access

T. Maciąg, A. Dębski and K. Rzyman

The Studies of Assumptions Accompanying the Calibration of High-Temperature Solution Calorimeter

The main thesis of the research was the problem concerning calibration of high-temperature solution calorimeter with aluminum. The important assumptions applied at calibration of a device with aluminum were verified. Enthalpy values determined during the experiment clearly suggest that the level of deformation and diameters of aluminum samples used for calibration are negligible. The assumption that the temperature of the samples at the moment they reach the bath level is very close to room temperature, is appropriate.

Open access

A. Dębski, M. H. Braga and W. Gąsior

The standard enthalpy of formation of the B78Li22 alloy was measured with the use of the water reaction calorimetric method at 25 °C (298 K). An X-ray diffraction study of the prepared sample was conducted. The obtained diffraction pattern was different from the patterns for the B3Li and B14Li3 phases. The standard enthalpy of formation obtained for the B78Li22 alloy was -39.0 ± 0.7 kJ/mole of atoms. This value corresponds well with the formation enthalpies of the phases from the boron-lithium system. Theoretical calculations of the standard enthalpy of formation were conducted for the B78Li22 alloy and the phases from B-Li system, which were investigated earlier. A discussion of the deviations observed between both sets of data (experimental and calculated) was performed. Additionally, DTA studies were performed for 14 alloys of the concentrations from 40 to 100 at. % of Li.

Open access

B. Onderka, A. Dębski and W. Gąsior

Abstract

A thermodynamic description of the entire ternary Bi-In-Zn system was obtained by the CALPHAD modelling of the Gibbs energy of the liquid phase. The experimental data on the phase equilibria and the thermodynamic properties published and complemented by the authors’ own experiments were taken into account. In order to verify the phase equilibria in the Bi-In-Zn system, 15 different samples were studied in the temperature range of 300-900 K by the DTA technique during heating and cooling cycles. Coexisting phases and their composition were analyzed by the SEM and EDX techniques for 9 distinct samples after their thermal equilibration at 373 K and 473 K.

Assessment and selected phase equilibrium calculations were performed with ThermoCalc and Pandat softwares, and compared with experimental data. The obtained results reproduce well the experimental data on both the phase equilibria and the thermodynamic properties in the optimized system.

Open access

B. Debski, M. Gralak, A. Gronowska-Senger and M. Gornicka

The influence of α-tocopherol supplementation on plasma concentration of this vitamin and insulin in sedentary or physically trained rats

Male young growing rats of Wistar strain (n=54) were fed a vitamin E deficient diet for 3 days of adaptation period and then 10 days of experimental period. After adaptation half of the rats ran, once per a day, on a treadmill with a rate of 2.0 m/s for 15 minutes for the following 10 days. Animals were given orally 0, 0.5, 1.0 or 4.0 mg/d/rat of α-tocopherol. The aim of the study was to evaluate the influence of physical training on tocopherol and insulin concentrations in the blood plasma of rats treated with different doses of vitamin E. The concentrations of α-tocopherol (HPLC-UV method used) and insulin (rat insulin specific RIA method used) were estimated in the blood plasma. Lower concentration of vitamin E in physically trained animals was observed, which may suggest increased needs of organisms for antioxidants, as a result of increased free radical production. In trained rats a lower concentration of plasma insulin was also observed. This effect is probably related to improvement in insulin action observed in organisms under physical exercise. The most significant impact on plasma α-tocopherol was due to its supplementation level. The treatment of rats with different doses of α-tocopherol was found to be not related to insulin concentration in plasma. A significant increase in feed conversion factor was noted in vitamin E treated animals. The obtained results suggest that the increased requirement of trained rats for antioxidants might be covered by α-tocopherol supple-mentation.

Open access

K. Kubok, L. Litynska-Dobrzynska, J. Wojewoda-Budka, A. Góral and A. Debski

Alloys of nominal composition Mg-3Zn-xCa (x = 0, 0.2, 0.5, 0.7, 1.0, 1.3) wt.% have been prepared by resistance melting and casting into graphite mould under argon atmosphere. All investigated alloys have revealed α(Mg) dendritic microstructures with intermetallic phases distributed in interdendritic spacing. The Mg4Zn7 has been identified as the main phase which coexists with α(Mg) in the Mg-Zn alloy. Calcium addition causes the formation of ternary Ca2Mg6Zn3 hexagonal phase, denoted also as Ca3MgxZn15-x . The increase of Mg/Zn ratio from 0.59 in Mg-3Zn-0.2Ca wt.% alloy to 2.72 in Mg-3Zn-1.3Ca wt.% alloy in this phase is connected with an increase in the lattice parameters. The microhardness of the Ca containing alloys increases up to 67 HV (for the alloy containing 1.3 wag.% Ca) compared to the 50 HV for Mg-3Zn wt.% alloy.