Experimental determination and thermodynamic modeling of the phase diagrams of Ge-Sb-Ag and Ge-Sb-In ternary systems

The results of experimental investigation and thermodynamic calculation of phase diagrams of Ge-Sb-Ag and Ge-Sb-In ternary systems are presented in this doctoral dissertation. Experimental part of the work includes preparation of the samples of selected compositions and their investigation using methods of differential thermal analysis (DTA), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), optical microscopy (LOM), measuring the hardness, microhardness and electric conductivity of alloys. Based on the obtained results characteristic phase transition temperatures, structural characteristics, phase compositions, mechanical properties and electric conductivity of the investigated alloys were determined. Calculation of phase diagrams of ternary Ge-Sb-Ag and Ge-Sb-In systems was performed using CALPHAD method and the corresponding thermodynamic software (Pandat ver. 8.1). Calculated results include liquidus projections, invariant reactions, characteristic vertical and isothermal sections for both investigated ternary systems.U doktorskoj disertaciji su izloţeni rezultati eksperimentalnog ispitivanja i termodinamiĉkog proraĉuna ravnoteţnih dijagrama stanja trojnih Ge-Sb-Ag i Ge-Sb-In sistema. U eksperimentalnom delu doktorske disertacije izvršena je priprema legura odabranih sastava koje su zatim ispitivane primenom metoda diferencijalno termijske analize (DTA), skenirajuće elektronske mikroskopije sa energo-disperzivnom spektrometrijom (SEM-EDS), X-ray difraktometrije (XRD), optiĉke mikroskopije (LOM), kao i merenjem tvrdoće, mikrotvrdoće i elektroprovodljivosti. Na osnovu dobijenih rezultata utvrĊene su karakteristiĉne temperature faznih transformacija, strukturne karakteristike, fazni sastav ispitivanih legura, mehaniĉke osobine i elektroprovodljivost legura. Proraĉun ravnoteţnih dijagrama stanja Ge-Sb-Ag i Ge-Sb-In sistema je izvršen primenom CALPHAD metode i odgovarajućeg termodinamiĉkog programa (Pandat ver. 8.1). Rezultati obuhvataju proraĉunate likvidus projekcije, invarijantne reakcije, karakteristiĉne vertikalne i izotermalne preseke za oba trojna sistema

Thermal characterization of the In–Sn–Zn eutectic alloy

Thermal properties, including melting temperature, latent heat of melting, specific heat capacity and thermal conductivity, of a low-melting In–Sn–Zn eutectic alloy were investigated in this work. The In–Sn–Zn eutectic alloy with nominal composition 52.7In-44.9Sn-2.4Zn (at.%) was prepared by the melting of pure metals under an argon atmosphere. The conducted assessment consisted of both theoretical and experimental approaches. Differential scanning calorimetry (DSC) was used for the measurement of melting temperature and latent heat, and the obtained results were compared with the results of thermodynamic calculations. The measured melting temperature and the latent heat of melting for the In–Sn–Zn eutectic alloy are 106.5±0.1 °C and 28.3±0.1 Jg-1, respectively. Thermal diffusivity and thermal conductivity of the In–Sn–Zn eutectic alloy were studied by the xenon-flash method. The determined thermal conductivity of the investigated eutectic alloy at 25 °C is 42.2±3.4 Wm-1K-1. Apart from providing insight into the possibility for application of the investigated alloy as the metallic phase-change material, the obtained values of thermal properties can also be utilized as input parameters for various simulation processes such as casting and soldering.Djordje Drobnjak - Memorial Issu

Experimental Investigation of Phase Equilibria in the Bi-Cu-Ge System

Phase diagram of the Bi-Ce-Ge ternary system has been investigated experimentally and thermodynamically extrapolated by using Pandat software. Experimental results were obtained using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray powder diffraction (XRD) methods. Examined ternary samples belong to two isothermal sections at 400 and 600 °C as well as three vertical sections Bi-CuGe, Cu-BiGe, and Ge-BiCu. No ternary compound has been detected in the equilibrated samples from the selected isothermal sections. Based on the presented experimental data and available literature data, description of the ternary system has been developed. A reasonable agreement between the experimental data and the calculated phase equilibria was obtained. As an example, ternary Cu80Bi10Ge10 alloy was selected for solidification simulations according to Scheil and Lever Rule assumptions as well as for simulation of the total fraction of each solid at different temperatures, latent heat, and total heat

Eksperimentalno ispitivanje i termodinamička analiza Bi-Ni-Pb faznog dijagrama

The article presents an experimental study of a phase diagram of a ternary Bi-Ni-Pb system using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray powder diffraction (XRD) analysis. The investigated ternary alloys were selected from three vertical sections (x(Bi)=0.75, x(Ni)=0.1 and x(Pb)=0.9) and two isothermal sections at 100 and at 300°C. The obtained experimental results were compared with the thermodynamically extrapolated phase diagram of the Bi-Ni-Pb ternary system based on the thermodynamic parameters for the constitutive binary systems available in literature. Reasonably close agreement between the experimental data and the calculated phase diagram was obtained.U ovom radu je predstavljeno eksperimentalno ispitivanje faznog dijagrama Bi-Ni-Pb ternarnog sistema uz pomoć diferencijalne termijske analize (DTA), skenirajućeg elektronskog mikroskopa (SEM) sa energijsko disperzivno spektrometrijom (EDS) i rentgenskom difrakcijom praha (XRD). Ispitivane ternarne legure su izabrane iz tri vertikalna preseka (x(Bi)=0.75, x(Ni)=0.1 i x(Pb)=0.9), i dva izotermalna preseka na 100 i 300°C. Rezultati eksperimenta su upoređeni sa termodinamički ekstrapolisanim faznim dijagramom Bi-Ni-Pb ternarnog sistema na osnovu termodinamičkih parametara sastavnih binarnih sistema koji su dostupni u literaturi. Utvrđeno je dobro slaganje između eksperimentalnih rezultata i proračunatog faznog dijagrama

Experimental Evaluation of 300 degrees C section of Cu-In-Ni Phase Diagram, Hardness and Electrical Conductivity of Selected Alloy

The paper reports comparative experimental and thermodynamic calculation of a Cu-In-Ni ternary system. An isothermal section of the Cu-In-Ni system at 300 degrees C was extrapolated using optimized thermodynamic parameters for the constitutive binary systems from literature. Microstructural and phase composition analysis were carried out using scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) and X-ray powder diffraction (XRD) technique. Brinell hardness and electrical conductivity of a selected number of alloy samples with compositions along three vertical sections (Cu-In0.5Ni0.5, In-Cu0.8Ni0.2, and x(In) = 0.4) of the studied Cu-In-Ni system were experimentally determined. Based on the obtained experimental results and by using appropriate mathematical models values of hardness and electrical conductivity for the whole ternary system were predicted. A close agreement between calculations and experimental results was obtained both in case of thermodynamic, electrical conductivity and hardness predictions

The influence of chemical composition on microstructure, hardness and electrical conductivity of Ag-Bi-In alloys at 100 °C

Considering possible applications and scarceness of literature data, Ag-Bi-In system was investigated in terms of microstructure, mechanical and electrical properties of ternary alloys from an isothermal section at 100oC. Based on the experimentally obtained results hardness and electrical conductivity of all ternary alloys from the ternary Ag-Bi-In system at 100oC were predicted. In addition, the selected isothermal section was further thermodynamically assessed and experimentally studied using scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), X-ray powder diffraction (XRD) analysis and light optical microscopy (LOM). Phase transition temperatures of alloys with overall compositions along vertical sections x(Ag)=0.5 as well as liquidus temperatures were experimentally determined by DTA. The experimentally obtained results were compared with literature data and with the results of thermodynamic calculation of phase equilibria based on CALPHAD method and corrected data for Ag-In binary system. Calculated liquidus projection, invariant equilibria and phase diagram of the Ag-Bi-In ternary system are presented as well

Thermal and microstructural analysis of the low-melting Bi-In-Pb alloy

Low-melting alloys, based on bismuth and indium, have found commercial use in soldering, safety devices, coatings, and bonding applications. In this respect, the accurate knowledge of their thermal properties such as melting and solidification temperatures, latent heat of melting, supercooling tendency, etc. is of large importance. In the present research, low-melting alloy with nominal composition Bi40In40Pb20(at. %) was investigated by means of scanning electron microscopy(SEM) with energy dispersive X-ray spectrometry (EDS) and by differential scanning calorimetry (DSC). Microstructural and chemical (SEM-EDS) analysis has revealed the existence of two coexisting phases in the prepared alloy, which was identified as BiInand (Pb). Melting and solidification temperatures and the related heat effects were measured by the DSC technique. The solidus temperature obtained from the DSC heating curves was 76.3 °C and the solidus temperature obtained from the corresponding DSC cooling runs was 61.2 °C. The experimentally obtained results were compared with the results of thermodynamic calculation according to CALPHAD (calculation of phase diagram) approach, and a close agreement was noticed.Milan Jovanović - Memorial Issu

Geochemistry of the cretaceous-tertiary boundary (Fish clay) at Stevns Klint (Denmark): Ir, Ni and Zn in kerogen

Geochemical analyses of trace metals (Ir, Ni and Zn) in the kerogen of the black marl of the Cretaceous-Tertiary boundary succession (Fish Clay) at Stevns Klint (Hojerup Church) were undertaken. The data for this kerogen were in accordance with a previous hypothesis(1) that this (insoluble) geoorganic polymer was derived from humic substances (mainly humic acids) of a nearshore soil. Substantial proportions of Ir, Ni and Zn within the kerogen structure were probably contained in these substances arriving at the sedimentary site. It is proposed that these humics were probably transported by acid surface waters (induced by the KT asteroid impact) into the shallow marine basin of Stevns Klint. It is also suggested that local leaching/weathering of the asteroidal impact fallout oil the land near these waters played an important role in providing Ir, Ni and Zn for these substances. Apparently, Ir, Ni and Zn of the kerogen were created by the chondritic component of the impact ejecta fallout

Study of microstructure and thermal properties of as-cast high carbon and high chromium tool steel

This work aims to investigate the microstructural and thermal properties of as-cast high carbon and high chromium cold work tool steel. The microstructure was investigated by using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) method. It was determined that at room temperature the microstructure of the investigated tool steel includes a lamellar network of M7C3 carbide precipitates along grain boundaries of ferrite grains in the base. Thermal diffusivity, specific heat capacity and thermal conductivity of the investigated steel alloy were determined in the temperature interval from 25 to 400 °C by using the laser-flash method. Thermal conductivity increases from 24.9 at 25 °C to 26.9 W/m·K at 400 °C. Phase transition temperatures in the temperature region from room temperature to 1250 °C were experimentally determined using differential scanning calorimetry (DSC). One endothermic effect in the temperature interval from 803 to 820 °C, corresponding to the ferrite/austenite phase transformation, was detected during sample heating. Experimental results were compared with the results of phase equilibria calculations obtained from the ThermoCalc software and TCFE6 database

The effect of silver addition on microstructure and thermal properties of the Cu–10%Al–8%Mn shape memory alloy

The influence of Ag addition on microstructure and thermal properties of the Cu-10%Al–8%Mn alloy was investigated in this work. Two alloys with designed compositions Cu-10%Al–8%Mn and Cu-10%Al–8%Mn-4%Ag (in wt.%) were prepared by induction melting of pure metals. Microstructures of the prepared samples were investigated in the as-cast state, after homogenization annealing and after quenching. The effects of different methods of heat treatment on the microstructure and transformation temperatures of the investigated Cu-10%Al–8%Mn and Cu-10%Al–8%Mn-4%Ag alloys were investigated using SEM-EDS and DSC techniques.It was determined that after induction melting microstructure of the both investigated alloys are primarily composed of martensite and a small amount of α-phase precipitates.Fully martensitic structure in both investigated alloys was obtained after direct quenching from the 850 °C into the ice water. Based on the DSC cooling curves it was determined that two-step martensite transformation for the both investigated alloys occur in the temperature interval from about 30 to -40 °C