Ljubiša Balanović

Comparative thermodynamic analysis and phase diagram prediction of the Ga-Sn-Zn system

Abstract The results of comparative thermodynamic analysis and phase diagram prediction of the Ga – Sn – Zn system are presented in this work. The thermodynamic study was done experimentally – using Oelsen calorimetry, for the section Ga – SnZneut, and analytically – according to the general solution model, for the whole system. Main thermodynamic quantities – integral and partial molar Gibbs excess energies, activities and activity coefficients were calculated over a wide temperature range. Additionally, the phase diagram of the section Ga – SnZneut was investigated using differential thermal analysis and predicted using the CALPHAD method. Comparison with available literature data showed reasonable agreement. The liquidus projection of the ternary Ga – Sn – Zn was also calculated.

Thermodynamics and characterization of shape memory Cu−Al−Zn alloys

Abstract The thermodynamic properties and the microstructure, hardness and electrical conductivity of shape memory alloys (SMAs) belonging to ternary Cu–Al–Zn system were studied by Muggianu model and experiment, respectively. The isothermal section of phase diagram at 293 K was calculated using Thermo-Calc software. Experiments were conducted by X-ray diffraction, light optic microscopy, scanning electron microscopy with energy dispersive X-ray spectrometry, hardness and electrical conductivity measurements. The calculated values of thermodynamic properties indicate that Cu shows good miscibility with Al and Zn in all investigated alloys. The microstructural analysis of samples reveals that the structure consists of large and polygonal grains.

Characterization of Au-Ga Alloys with Low Gold Content

Abstract The results of an experimental investigation of structural, mechanical and electrical characteristics of the alloys in Au-Ga system are presented in this paper. Selected alloys AuxGay (x = 0.1 — 0.3) were examined using light microscopy and SEM-EDX analysis as well as hardness, microhardness and electroconductivity measurements.

Study of microstructure and thermal properties of the low-melting Bi–In eutectic alloys

This study reports the results of microstructure and thermal analysis of low-melting Bi–In alloys with potential for commercial application in the field of phase change materials. Three eutectic alloys Bi–47.44In, Bi–66.33In, Bi–77.92In (all in at.%) were prepared and investigated by means of scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS) and differential scanning calorimetry (DSC). Microstructure of the prepared eutectic alloys was analysed using SEM–EDS, and identification of co-existing phases was done. Melting temperatures and latent heats of eutectic melting were measured using DSC technique. Experimentally obtained results were compared with the results of thermodynamic calculation according to CALPHAD (calculation of phase diagram) method, and good mutual agreement was noticed.

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.

Thermal and structural characteristics of a eutectic Au-Ge alloy

Abstract The Au-Ge alloy is useful for bonding applications in microelectronic and optoelectronic packages. Also, recent investigations show that Au-Ge system could present a lead-free solder candidate. The results of characterization of the eutectic alloy from binary Au-Ge system are presented in this paper. Experimental research was done using thermal analysis (differential thermal analysis, DTA) and structural investigation by light optic microscopy (LOM) and scanning electron microscopy with EDS (SEM-EDS). The eutectic temperature of 359 °C was detected using thermal analysis, while eutectic structure was confirmed using microstructural analysis. Obtained results were compared with recent literature references and good mutual agreement was noticed.

The effect of zinc on the microstructure and phase transformations of casting Al-Cu alloys

Copper is one of the main alloying elements for aluminum casting alloys. As an alloying element, copper significantly increases the tensile strength and toughness of alloys based on aluminum. The copper content in the industrial casting aluminum alloys ranges from 3,5 to 11 wt.%. However, despite the positive effect on the mechanical properties, copper has a negative influence on the corrosion resistance of aluminum and its alloys. In order to further improve the properties of Al-Cu alloys they are additional alloyed with elements such as zinc, magnesium and others. In this work experimental and analytical examination of the impact of zinc on the microstructure and phase transformations of Al-Cu alloys was carried out. In order to determine the effect of the addition of zinc to the structure and phase transformations of Al-Cu alloys two alloys of Al-Cu-Zn system with selected compositions were prepared and then examined using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX). The experimental results were compared with the results of thermodynamic calculations of phase equilibria.

Mechanical and electrical properties of Sb-Ga50Au10In40 alloys

Abstract In this publication, results are presented which have been obtained by investigation of mechanical and electrical properties of alloys belonging to Sb-Ga50Au10In40 section of quaternary Au-Ga-In-Sb system, which is the basis for the development of new lead-free solder materials. The experiments were conducted using Brinell method for hardness measurement, apparatus PTM-3 for microhardness measurement and instrument Foerster SIGMATEST 2.069 for measuring of electrical conductivity. The microstructure of samples was analyzed using optical microscopy.