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

10.30544/564 ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 385-394
Author(s):  
Dragan Miroslav Manasijevic ◽  
Ljubiša Balanović ◽  
Tamara Holjevac Grgurić ◽  
Milan Gorgievski ◽  
Ivana Marković ◽  
...  
Keyword(s):  
Solidus Temperature ◽  
Microstructural Analysis ◽  
Nominal Composition ◽  
Scanning Calorimetry ◽  
Eds Analysis ◽  
Heat Effects ◽  
Latent Heat Of Melting ◽  
Diagram Approach ◽  
Prepared Alloy ◽  
Melting And Solidification

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 BiIn and (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.

scholarly journals Thermal characterization of the In–Sn–Zn eutectic alloy

10.30544/456 ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 325-334
Author(s):  
Dragan Manasijević ◽  
Ljubiša Balanović ◽  
Vladan Ćosović ◽  
Duško Minić ◽  
Milena Premović ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Melting Temperature ◽  
Latent Heat ◽  
Eutectic Alloy ◽  
Metallic Phase ◽  
Flash Method ◽  
Nominal Composition ◽  
Scanning Calorimetry ◽  
Latent Heat Of Melting

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.

scholarly journals Effect of Molybdenum Content on the Corrosion and Microstructure of Low-Ni, Co-Free Maraging Steels

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 852
Author(s):  
Asiful H. Seikh ◽  
Hossam Halfa ◽  
Mahmoud S. Soliman
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Alloying Element ◽  
X Ray ◽  
Maraging Steels ◽  
Eds Analysis ◽  
Electroslag Refining

Molybdenum (Mo) is an important alloying element in maraging steels. In this study, we altered the Mo concentration during the production of four cobalt-free maraging steels using an electroslag refining process. The microstructure of the four forged maraging steels was evaluated to examine phase contents by optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Additionally, we assessed the corrosion resistance of the newly developed alloys in 3.5% NaCl solution and 1 M H2SO4 solution through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Furthermore, we performed SEM and energy-dispersive spectroscopy (EDS) analysis after corrosion to assess changes in microstructure and Raman spectroscopy to identify the presence of phases on the electrode surface. The microstructural analysis shows that the formation of retained austenite increases with increasing Mo concentrations. It is found from corrosion study that increasing Mo concentration up to 4.6% increased the corrosion resistance of the steel. However, further increase in Mo concentration reduces the corrosion resistance.

scholarly journals Redox Oxides-Based Solar Thermochemistry and Its Materialization to Reactor/Heat Exchanger Concepts for Efficient Solar Energy Harvesting, Transformation and Storage

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Christos Agrafiotis ◽  
Mathias Pein ◽  
Dimitra Giasafaki ◽  
Stefania Tescari ◽  
Martin Roeb ◽  
...  
Keyword(s):  
Scanning Calorimetry ◽  
Chemical Expansion ◽  
Solar Energy Harvesting ◽  
Cyclic Operation ◽  
Heat Effects ◽  
Carbon Dioxide Splitting ◽  
Oxygen Pumping ◽  
Coefficient Of Linear Expansion ◽  
A Site

Ca-Mn-based perovskites doped in their A- and B-site were synthesized and comparatively tested versus the Co3O4/CoO and (Mn,Fe)2O3/(Mn,Fe)3O4 redox pairs with respect to thermochemical storage and oxygen pumping capability, as a function of the kind and extent of dopant. The perovskites' induced heat effects measured via differential scanning calorimetry are substantially lower: the highest reaction enthalpy recorded by the CaMnO3–δ composition was only 14.84 kJ/kg compared to 461.1 kJ/kg for Co3O4/CoO and 161.0 kJ/kg for (Mn,Fe)2O3/(Mn,Fe)3O4. Doping of Ca with increasing content of Sr decreased these heat effects; more than 20 at % Sr eventually eliminated them. Perovskites with Sr instead of Ca in the A-site exhibited also negligible heat effects, irrespective of the kind of B site cation. On the contrary, perovskite compositions characterized by high oxygen release/uptake can operate as thermochemical oxygen pumps enhancing the performance of water/carbon dioxide splitting materials. Oxygen pumping via Ca0.9Sr0.1MnO3–δ and SrFeO3–δ doubled and tripled, respectively, the total oxygen absorbed by ceria during its re-oxidation versus that absorbed without their presence. Such effective pumping compositions exhibited practically no shrinkage during one heat-up/cool-down cycle. However, they demonstrated an increase of the coefficient of linear expansion due to the superposition of “chemical expansion” to thermal-only one, the effect of which on the long-term dimensional stability has to be further quantified through extended cyclic operation.

scholarly journals Physical Properties of Copper Based MMC Strengthened with Alumina

2014 ◽  
Vol 14 (2) ◽  
pp. 85-90 ◽  
Author(s):  
J. W. Kaczmar ◽  
K. Granat ◽  
A. Kurzawa ◽  
E. Grodzka
Keyword(s):  
Physical Properties ◽  
Squeeze Casting ◽  
Liquid Copper ◽  
Microstructural Analysis ◽  
Copper Matrix ◽  
Ceramic Particles ◽  
Casting Technique ◽  
Eds Analysis ◽  
Alumina Particles ◽  
Porous Compacts

Abstract The aim of this work is the development of Cu-Al2O3 composites of copper Cu-ETP matrix composite materials reinforced by 20 and 30 vol.% Al2O3 particles and study of some chosen physical properties. Squeeze casting technique of porous compacts with liquid copper was applied at the pressure of 110 MPa. Introduction of alumina particles into copper matrix affected on the significant increase of hardness and in the case of Cu-30 vol. % of alumina particles to 128 HBW. Electrical resistivity was strongly affected by the ceramic alumina particles and addition of 20 vol. % of particles caused diminishing of electrical conductivity to 20 S/m (34.5% IACS). Thermal conductivity tests were performed applying two methods and it was ascertained that this parameter strongly depends on the ceramic particles content, diminishing it to 100 Wm-1K-1 for the composite material containing 30 vol.% of ceramic particles comparing to 400 Wm-1K-1 for the unreinforced copper. Microstructural analysis was carried out using SEM microscopy and indicates that Al2O3 particles are homogeneously distributed in the copper matrix. EDS analysis shows remains of silicon on the surface of ceramic particles after binding agent used during preparation of ceramic preforms.

Microstructure of Sn-20In-2.8Ag solder and mechanical properties of joint with Cu

2019 ◽  
Vol 31 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Fen Peng ◽  
Wensheng Liu ◽  
Yunzhu Ma ◽  
Chaoping Liang ◽  
Yufeng Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Eutectic Reaction ◽  
Scanning Calorimetry ◽  
Good Reliability ◽  
Content Type ◽  
Dsc Measurements ◽  
Lap Shear ◽  
Evolution Characteristics ◽  
Three Phase ◽  
Melting And Solidification

Purpose To explore substitutes for traditional Sn-Pb solder, Sn-20In-2.8Ag was considered because of its appropriate melting temperature, good reliability and high ductility at less than 100°C. However, the mechanical properties of Sn-20In-2.8Ag were not satisfactory. The reason for the poor mechanical properties of the Sn-20In-2.8Ag/Cu joint was revealed, and a way to solve the problem was found. Design/methodology/approach The microstructure evolution, characteristics of melting and solidification and joining performance with Cu were investigated using scanning electron microscopy (SEM), electron probe microanalysis, differential scanning calorimetry (DSC) and mechanical testing. Findings SEM results showed that the microstructure of Sn-20In-2.8Ag was composed of coarse dendritic Ag2In and γ phases, with Ag2In distributed at the grain boundaries. DSC measurements revealed that small amount of low temperature eutectic reaction, L → Ag2In + β + γ, occurred at 112.9°C. This reaction was caused by the segregation of indium, which is a process that has a strong driving force. In the lap-shear testing, a crack propagated along the grain boundary of the solder, and failure showed an intergranular fracture. This failure was connected with the three-phase eutectic and coarse Ag2In. Thus, to improve the mechanical properties, segregation of indium should be reduced and coarsening of Ag2In should be prevented. Originality/value The reason for the unsatisfactory mechanical properties of Sn-20In-2.8Ag was revealed via microstructural observations and solidification analysis, and the way to solve this problem was found.

scholarly journals Measuring Enthalpies of Formation Using Thick Multilayer Foils and Differential Scanning Calorimetry

1995 ◽  
Vol 382 ◽  
Author(s):  
T.P. Weihs ◽  
T.W. Barbee ◽  
M.A. Wall
Keyword(s):  
Differential Scanning Calorimetry ◽  
Diffusion Constant ◽  
Enthalpies Of Formation ◽  
Nominal Composition ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Two Phases ◽  
Sputter Deposited ◽  
Multi Phase

ABSTRACTThe exothermic, solid state reaction of Al and Zr has been studied in thick AL/Zr multilayers using Differential Scanning Calorimetry and X-ray diffraction. The multilayersamples were magnetron sputter deposited into highly textured alternate layers of Al and Zr with nominal composition A13Zr. The samples used in this study were 47μm thick with a 427Å period. When samples were isochronally scanned from 25º to 725ºC, a large exotherm at ˜350ºC was followed by one or two smaller exotherms at ˜650ºC. The first exotherm is dominated by a diffusionbased reaction of Al and Zr that produces two phases in isochronal scans: amorphous AI-Zrand cubic A13Zr, and two additional phases in isothermal anneals: A12Zr and tetragonal AI3Zr. The exothermic heat from this multi-phase reaction is measured using isochronal scans and isothermal anneals, and the heat flow is analyzed using a l-D diffusion based model. An average activation energy and a diffusion constant are determined. In the isothermal scans, the total exothermic heat increases linearly with √ime, and layer thicknesses vary linearly with heat.

Thermal transport, thermomechanical, and dielectric properties of chalcogenide Se98–xAg2Inx (x = 0, 2, 4, 6) system

2014 ◽  
Vol 92 (7/8) ◽  
pp. 648-653
Author(s):  
C. Dohare ◽  
N. Mehta
Keyword(s):  
Dielectric Constant ◽  
Electron Microscope ◽  
Dielectric Loss ◽  
Thermal Transport ◽  
Microstructural Analysis ◽  
Thermomechanical Properties ◽  
X Ray Diffraction ◽  
Glassy System ◽  
Scanning Calorimetry ◽  
Transmission Electron

The present work reports a detailed study of some physical properties of some novel glasses of Se98–xAg2Inx (x = 0, 2, 4, 6) system. Measurements of thermal transport properties (i.e., thermal conductivity, κ, and thermal diffusivity, χe) have been carried out using the transient plane source technique. Specific heat measurements have been done by differential scanning calorimetry. Thermomechanical properties (i.e., Vickers hardness, Hv, and modulus of elasticity, E) have been evaluated by the indenter test. The minimal energy for formation of microvoids, Eh, and microvoids volume, Vh, of the previously mentioned glassy system are discussed in terms of microhardness, Hv. Temperature and frequency dependence of dielectric constant, ε1, and dielectric loss, ε2, for the same system were measured in the frequency (50 Hz – 1000 kHz) and temperature (303–338 K) range. The experimental results illustrate that the values of dielectric constant, ε1, and dielectric loss, ε2, are decreased with frequency and increased with temperature. The maximum barrier height, Wb, is calculated using the dielectric measurements according to the Guintini equation. The morphology and microstructural analysis of as-prepared alloys are confirmed by X-ray diffraction, scanning electron microscope, and transmission electron microscope.

scholarly journals Synthesis and characterisation of (La,Pr) monazite solid solution series

2014 ◽  
Vol 70 (a1) ◽  
pp. C1106-C1106
Author(s):  
Antje Hirsch ◽  
Andreas Neumann ◽  
Anja Wätjen ◽  
Julia Heuser ◽  
Anja Thust ◽  
...  
Keyword(s):  
Solid Solution ◽  
Nuclear Waste ◽  
Linear Increase ◽  
Nominal Composition ◽  
Gravimetric Analysis ◽  
Solid Solution Series ◽  
Scanning Calorimetry ◽  
Average Deviation ◽  
X Ray ◽  
Solution Series

Monazite type ceramics are considered as potential ceramic storage materials for high level nuclear waste. Natural monazite is a host for radioactive elements like U and Th without becoming metamict due to radiation damage. Monazites are also known for their chemical flexibility and thermal stability. In this context, a solid solution series of (La,Pr)PO4 was synthesised as powders and single crystals and characterised by PXRD (Powder X-Ray Diffraction analysis), EMPA (Electron Microprobe Analysis), TGA (Thermal Gravimetric Analysis) and DSC (Differential Scanning Calorimetry). La and Pr were used as inactive surrogates for the minor actinides Am, Cm and Np, which represent major challenges in nuclear waste management due to their long half-life and high radiotoxicity. The powder samples were prepared following the protocol of [1]. Ln2O3 were mixed with NH4H2PO4 in excess. Powders were ground, pressed, and heated for one day at 12500C in air. X-Ray laboratory and synchrotron data showed that all samples were single phase. A decrease in the lattice parameters and volume with increasing Pr content was observed as expected due to the smaller radius of Pr3+ with respect to La3+ in nine fold coordination. The monoclinic angle β showed a linear increase. Using EMPA, the composition of all samples was determined. The average deviation from the nominal composition was calculated to be about 4 mol% which covers both, sample inhomogeneity and, more importantly, experimental challenges due to grain shape and porosity. In TGA and DSC curves, similar behaviour for all samples was observed, except for the Pr end member. This unsolved issue is currently under investigation. Complementary IR and Raman spectroscopic data showed the expected linear trends [2]. This behaviour was also reported for LnPO4 (Ln = La-Gd) [3]. The author gratefully thanks the BMBF (02 NUK 021E) for financial funding.

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