Structural and mechanical properties of some aluminum-based binary alloys

The purpose of this study is to investigate structural and mechanical properties of some aluminum-based alloys. Microstructures of the Al-Sn and Al-Zn binary alloys were examined using optic microscopy. The mechanical properties - Vickers hardness and micro hardness tests were investigated according to standard procedure

Mechanical and magnetic properties of composite materials with polymer matrix

Many of modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloys, ceramics, and polymeric materials. Material property combinations and ranges have been extended by the development of composite materials. Development of Nd-Fe-B/polymer composite magnetic materials has significantly increased interest in research and development of bonded magnets, since particles of Nd-Fe-B alloys are proved to be very suitable for their production. This study investigates the mechanical and magnetic properties of compression molded Nd-Fe-B magnets with different content of magnetic powder in epoxy matrix. Mechanical properties were investigated at ambient temperature according to ASTM standard D 3039-00. The obtained results show that tensile strength and elongation decrease with an increase of Nd-Fe-B particles content in epoxy matrix. The modulus of elasticity increases, which means that in exploitation material with higher magnetic powder content, subjected to the same level of stress, undergoes 2 to 3.5 times smaller deformation. Scanning Electron Microscopy (SEM) was used to examine the morphology of sample surfaces and fracture surfaces caused by the tensile strength tests. The results of SQUID magnetic measurements show an increase of magnetic properties of the investigated composites with increasing content of Nd-Fe-B particles

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

Phase diagram investigation and characterization of alloys in Bi-Ga10Sb90 section of Ga-Bi-Sb system

The results of phase equilibria investigation and characterization of the alloys in the Bi-Ga10Sb90 section of Ga-Bi-Sb system are presented in this paper. Phase diagram of the mentioned section has been calculated according to CALPHAD model, using Pandat software. In the frame of alloys characterization, structural, mechanical and electrical characteristics were determined using SEM-EDX analysis, microhardness and electroconductivity measurements

Phase transformations and thermal conductivity of the In-Ag alloys

Phase transformations and thermal conductivity of three In-Ag alloys with 5, 15, and 45 wt.% of Ag were experimentally investigated in the present work. Phase transition temperatures were measured using differential scanning calorimetry (DSC). DSC heating scans were compared with the equilibrium and non-equilibrium solidification paths, calculated by using optimized thermodynamic parameters from literature and calculation of phase diagrams (CALPHAD) method.  The flash method was employed for the determination of thermal diffusivity and thermal conductivity of the investigated alloys in the temperature range from 25 to 100 °C. It has been found that an increase in silver content does not lead to an increase in the thermal conductivity of the investigated alloys. Thermal conductivities for all three investigated In-Ag alloys slightly decrease with temperature increasing

EFFECT OF PARTICLE SHAPE AND SIZE OF COPPER POWDERS ON THE PROPERTIES OF SINTERED PARTS

The particle shape and size of the starting powders represent the most important physical properties, on which the quality of the compacts and final sintered products depends. Two types of powder were analyzed in the paper - electrolytic copper powder with a dendritic particle shape and water-atomized copper powder with an irregular particle shape. The starting powders were sieved through a sieve system with openings of 45 μm, 80 μm, and 120 μm. The characterization of the obtained fractions of both powders was performed by determining the shape and dimensions of the particles using SEM microscopy in combination with ImageJ software, and the apparent density and flow rate were determined using the Hall flowmeter funnel. Pressing of each powder fraction was done using a pressure of 600 MPa. The compacts were further sintered at 1000°C for 2 hours to obtain the final sintered parts. After sintering, their density, hardness, and electrical conductivity were determined and their microstructure was analyzed. The results indicate a great influence of the characteristics of the starting powders on the properties of the final parts obtained by the powder metallurgy route. The particle shape of the powders had a more pronounced influence compared to the particle size

Thermal transport properties and microstructure of the solid Bi-Cu alloys

Thermal transport properties of solid Bi-Cu alloys have been investigated over a wide composition range and temperature range ranging from 25 to 250 °C. The flash method was used to determine thermal diffusivity. Thermal diffusivity was discovered to decrease continuously with increasing temperature and bismuth content. The indirect Archimedean method was used to determine the density of the Bi-Cu alloys at 25 °C. The obtained results show that the density of the studied alloys decreases slightly as the copper content increases. Thermal conductivity of the alloys was calculated using measured diffusivity, density, and a calculated specific heat capacity. The thermal conductivity of the studied Bi-Cu alloys decreases with increasing temperature and bismuth content, similar to thermal diffusivity. SEM with energy dispersive X-ray spectrometry (EDS) and differential scanning calorimetry (DSC) were used to examine the microstructure and melting behavior of Bi-Cu alloys, respectively. The eutectic temperature was measured to be 269.9±0.1 °C, and the measured phase transition temperatures and heat effects were compared to thermodynamic calculations using the CALPHAD method

Structural and mechanical properties of some aluminum-based binary alloys

The purpose of this study is to investigate structural and mechanical properties of some aluminum-based alloys. Microstructures of the Al-Sn and Al-Zn binary alloys were examined using optic microscopy. The mechanical properties - Vickers hardness and micro hardness tests were investigated according to standard procedure

Characterization of the Ga-InSb system: experimental investigation of thermal, structural, mechanical and electrical properties

The materials based on gallium-antimonide are widely used in electronic industry in the production of various electronic devices. The results of characterization of selected alloys in the Ga-InSb system obtained by experimental investigation of some thermal, structural, mechanical and electrical properties are presented in this paper. Applied experimental techniques included: differential thermal analysis, light optical microscopy, scanning electron microscopy with EDX, hardness, micro hardness and electrical conductivity measurements

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