scholarly journals Interactions of Cu-substrates with titanium-alloyed Sn-Zn solders

2006 ◽  
Vol 42 (1) ◽  
pp. 45-56 ◽  
Author(s):  
D. Soares ◽  
J. Barbosa ◽  
C. Vilarinho
Keyword(s):  
Thermal Analyses ◽  
Copper Substrate ◽  
Reaction Times ◽  
Chemical Compositions ◽  
Eutectic Alloys ◽  
Diffusion Couples ◽  
Phase Layer ◽  
Cu Substrates ◽  
Series Of Experiments ◽  
Solid Liquid

The interactions of copper substrate with titanium-alloyed Sn-Zn eutectic solders have been studied. Two series of experiments have been performed. The first one consisted in differential thermal analyses of Sn-Zn nearly eutectic alloys containing from 1.3 to 2.2 wt. % Ti. Diffusion couples consisted of Cu-wires and Sn-Zn-Ti liquid solders, produced at 250 and 275 OC have been prepared in the second series,. The contact times were up to 3600 s. The contact zones have been characterized by optical and scanning electron microscope. Two layers have been found along the interfaces solid/liquid. The first and the second layers are identical, respectively, with ? and ? phases of the Cu-Zn system. No changes of the chemical compositions were detected for the tested temperatures and reaction times. Continuous parabolic growth of the total diffusion zone thickness with the time of diffusion is observed. The growth is due mainly to one the formed layers (? ) while the thickness of the ?-phase layer, stays almost constant for all tested diffusion times and temperatures.

Diffusion Paths for the Formation of Half-Heusler Type Thermoelectric Compound TiNiSn

2008 ◽  
Vol 1128 ◽  
Author(s):  
Chihiro Asami ◽  
Yoshisato Kimura ◽  
Takuji Kita ◽  
Yoshinao Mishima
Keyword(s):  
Thermoelectric Properties ◽  
Single Phase ◽  
Waste Heat ◽  
Electric Energy ◽  
Diffusion Couples ◽  
Phase Layer ◽  
Equilibrium Solidification ◽  
Diffusion Paths ◽  
Solid Liquid ◽  
Ternary Peritectic Reaction

AbstractHalf-Heusler compound TiNiSn is one of the most promising candidates of thermoelectric materials which can be used to directly convert the waste heat to clean electric energy at high temperatures (around 1000 K). Thermoelectric power generation is an appealing approach for conserving energy and preserving the global environment. Half-Heusler compounds have the cubic C1b type ordered structure and show semiconducting behavior when their valence electron count (VEC) is around 18. TiNiSn is the most attractive one not only because it has excellent thermoelectric properties but also it consists of eco-friendly elements which are neither toxic nor costly. However, TiNiSn has a bothersome problem that fabrication of single phase TiNiSn alloy is quite difficult. We have found that TiNiSn phase forms by the ternary peritectic reaction. Thereby, inevitable non-equilibrium solidification results in the formation of impurity coexisting phases which tend to decrease thermoelectric properties. In the present work, to establish the basis of new fabrication processes for TiNiSn alloys, we have started from the investigation on the diffusion paths which are closely related to the formation of TiNiSn phase. The diffusion behavior was evaluated using solid/liquid diffusion couples composed of the binary Ti-Ni intermetallic compounds and Sn liquid phase, where we have selected TiNi, TiNi3 and Ti2Ni as solid phases for instance. The most interesting result is that the single-phase TiNiSn phase layer forms at the TiNi/Sn(L) interface during annealing at 1073 K for only 1 h. Moreover, faceted grains of TiNiSn single-crystal grow at the interface toward the liquid Sn phase. We have confirmed two interesting microstructural features using EBSD analyses. One is that most of these TiNiSn single-crystals have the same crystallographic orientation, and the other is that TiNiSn phase layer formed on the TiNi side of the interface consists of very fine sub-microns grains. While TiNiSn solely forms at the TiNi interface, Heusler TiNi2Sn also forms with TiNiSn at the TiNi3 interface and Ti6Sn5 tends to coexist at the Ti2Ni interface.

EFFECT OF Mg AND TEMPERATURE ON Fe–Al ALLOY LAYER IN Fe/(Zn–6%Al–x%Mg) SOLID–LIQUID DIFFUSION COUPLES

2017 ◽  
Vol 24 (Supp01) ◽  
pp. 1850010
Author(s):  
LIU LIANG ◽  
YA-LING LIU ◽  
YA LIU ◽  
HAO-PING PENG ◽  
JIAN-HUA WANG ◽  
...  
Keyword(s):  
Diffusion Couple ◽  
Alloy Layer ◽  
Al Alloy ◽  
Diffusion Couples ◽  
Phase Layer ◽  
Liquid Diffusion ◽  
Time Period ◽  
Phase Layers ◽  
Diffusion Temperature ◽  
Solid Liquid

Fe/(Zn–6%Al–[Formula: see text]%Mg) solid–liquid diffusion couples were kept at various temperatures for different periods of time to investigate the formation and growth of the Fe–Al alloy layer. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were used to study the constituents and morphology of the Fe–Al alloy layer. It was found that the Fe2Al5Znxphase layer forms close to the iron sheet and the FeAl3Znxphase layer forms near the side of the melted Zn–6%Al–3%Mg in diffusion couples. When the Fe/(Zn–6%Al–3%Mg) diffusion couple is kept at 510[Formula: see text]C for more than 15[Formula: see text]min, a continuous Fe–Al alloy layer is formed on the interface of the diffusion couple. Among all Fe/(Zn–6%Al–[Formula: see text]%Mg) solid–liquid diffusion couples, the Fe–Al alloy layer on the interface of the Fe/(Zn–6% Al–3% Mg) diffusion couple is the thinnest. The Fe–Al alloy layer forms only when the diffusion temperature is above 475[Formula: see text]. These results show that the Fe–Al alloy layer in Fe/(Zn–6%Al–[Formula: see text]%Mg) solid–liquid diffusion couples is composed of Fe2Al5Znxand FeAl3Znxphase layers. Increasing the diffusing temperature and time period would promote the formation and growth of the Fe–Al alloy layer. When the Mg content in the Fe/(Zn–6%Al–[Formula: see text]%Mg) diffusion couples is 3%, the growth of the Fe–Al alloy layer is inhibited. These results may explain why there is no obvious Fe–Al alloy layer formed on the interface of steel with a Zn–6%Al–3%Mg coating.

scholarly journals Nanotribological Performance Factors for Aqueous Suspensions of Oxide Nanoparticles and Their Relation to Macroscale Lubricity

Lubricants ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 49 ◽  
Author(s):  
Biplav Acharya ◽  
Tyler N. Pardue ◽  
Liangliang Su ◽  
Alex I. Smirnov ◽  
Donald W. Brenner ◽  
...  
Keyword(s):  
Initial Study ◽  
Atomic Scale ◽  
Frictional Drag ◽  
Friction Coefficients ◽  
Materials Properties ◽  
Performance Factors ◽  
Aqueous Suspensions ◽  
Series Of Experiments ◽  
Motional Resistance ◽  
Solid Liquid

Quartz crystal microbalance (QCM) measurements of nanotribological properties of statistically diverse materials combinations of nanoparticles and substrate electrodes in aqueous suspensions are reported and compared to macroscale measurements of the same materials combinations for a subset of the nanoparticle combinations. Four ceramic nanoparticles, TiO2, SiO2, Al2O3, and maghemite (γ-Fe2O3) and ten substrate materials (Au, Al, Cr, Cu, Mo, Ni, Pt, SiO2, Al2O3, and SS304) were studied. The QCM technique was employed to measure frequency and motional resistance changes upon introduction of nanoparticles into the water surrounding its liquid-facing electrode. This series of experiments expanded prior studies that were often limited to a single nanoparticle - solid liquid combination. The variations in QCM response from one nanoparticle to another are observed to be far greater than the variation from one substrate to another, indicating that the nanoparticles play a larger role than the substrates in determining the frictional drag force levels. The results were categorized according to the direction of the frequency and motional resistance changes and candidate statistical performance factors for the datasets were generated. The performance factors were employed to identify associations between the QCM atomic scale results and the macroscale friction coefficient measurements. Macroscale measurements of friction coefficients for selected systems document that reductions (increases) in motional resistance to shear, as measured by the QCM, are linked to decreases (increases) in macroscale friction coefficients. The performance factors identified in the initial study therefore appear applicable to a broader set of statistically diverse samples. The results facilitate full statistical analyses of the data for identification of candidate materials properties or materials genomes that underlie the performance of nanoparticle systems as lubricants.

scholarly journals Inhibitory and Facilitatory Cueing Effects: Competition between Exogenous and Endogenous Mechanisms

Vision ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 40 ◽  
Author(s):  
Alfred Lim ◽  
Vivian Eng ◽  
Caitlyn Osborne ◽  
Steve M. J. Janssen ◽  
Jason Satel
Keyword(s):  
Behavioral Inhibition ◽  
Inhibition Of Return ◽  
Reaction Times ◽  
Target Onset ◽  
Saccadic Reaction Times ◽  
Series Of Experiments ◽  
Endogenous Activity ◽  
Onset Asynchrony ◽  
Delayed Responses

Inhibition of return is characterized by delayed responses to previously attended locations when the cue-target onset asynchrony (CTOA) is long enough. However, when cues are predictive of a target’s location, faster reaction times to cued as compared to uncued targets are normally observed. In this series of experiments investigating saccadic reaction times, we manipulated the cue predictability to 25% (counterpredictive), 50% (nonpredictive), and 75% (predictive) to investigate the interaction between predictive endogenous facilitatory (FCEs) and inhibitory cueing effects (ICEs). Overall, larger ICEs were seen in the counterpredictive condition than in the nonpredictive condition, and no ICE was found in the predictive condition. Based on the hypothesized additivity of FCEs and ICEs, we reasoned that the null ICEs observed in the predictive condition are the result of two opposing mechanisms balancing each other out, and the large ICEs observed with counterpredictive cueing can be attributed to the combination of endogenous facilitation at uncued locations with inhibition at cued locations. Our findings suggest that the endogenous activity contributed by cue predictability can reduce the overall inhibition observed when the mechanisms occur at the same location, or enhance behavioral inhibition when the mechanisms occur at opposite locations.

scholarly journals Back-Diffusion In Crystal Growth. Eutectics

2015 ◽  
Vol 60 (3) ◽  
pp. 2403-2407 ◽  
Author(s):  
W. Wołczyński
Keyword(s):  
Differential Equation ◽  
Crystal Growth ◽  
Current Model ◽  
Solute Segregation ◽  
Solidification Path ◽  
Back Diffusion ◽  
Eutectic Alloys ◽  
Equilibrium Solidification ◽  
Solid Liquid ◽  
Non Equilibrium

Abstract Solute segregation/redistribution model for some eutectic alloys is presented. The differential equation for the solute micro-segregation during solidification accompanied by the back-diffusion is formulated. The solution to this equation results in the definitions of: solidification path, solid/liquid (s/l) interface path and redistribution path. An equation for the estimation of the amount of equilibrium and non-equilibrium precipitates is also delivered. It is proved that the current model is universal one. Thus, the model reduces perfectly, mathematically to both description of diffusion-less solidification and model of equilibrium solidification.

ELECTROCATALYTIC ACTIVITY OF Ni–Mn–Sn ALLOY FOAMS FOR OXYGEN EVOLUTION REACTION (OER)

2019 ◽  
Vol 27 (03) ◽  
pp. 1950122
Author(s):  
NILOOFAR TAHERIAN ◽  
SOHRAB SANJABI
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Copper Substrate ◽  
Grazing Incidence ◽  
Alkaline Media ◽  
Chemical Compositions ◽  
X Ray ◽  
Sulfate Bath ◽  
Surface Morphologies

This study carried out to examine electrocatalytic activity of Ni–Mn–Sn alloy foams for oxygen evolution reaction (OER) in alkaline media. As the first step, Ni–Mn–Sn alloy foams were prepared of sulfate bath on copper substrate. Next, after optimization of electrodeposition condition by cyclic voltammetry (CV) test, foams were electrodeposited at different current densities 100, 120, 140 and 180[Formula: see text]mA[Formula: see text]⋅[Formula: see text]cm[Formula: see text]. Then, they were characterized by field emission scanning electron microscopy (FE-SEM) along with energy disperse x-ray spectroscopy (EDS) to investigate surface morphologies and chemical compositions. According to FE-SEM results, it was revealed that formation of foam like structures were due to the presence of dynamic hydrogen bubbles template (DHBT). To survey their structure, grazing incidence X-ray diffractometer (GIXRD) analysis was performed. The resulted diffraction pattern determined not only FCC nickel structure of foams, but also mixed phases composed. Following this, Ni–Mn–Sn alloy foams were placed in 0.1 M KOH and related CV tests were applied to measure their electrocatalytic activity for OER. This study demonstrated good electrocatalytic activity for Ni–Mn–Sn alloy foams by showing favorable oxygen evolution overpotenitals and Tafel slopes.

scholarly journals Morphological Development of Sub-Grain Cellular/Bands Microstructures in Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1204 ◽  
Author(s):  
Xihe Liu ◽  
Xin Zhou ◽  
Ben Xu ◽  
Jing Ma ◽  
Congcong Zhao ◽  
...  
Keyword(s):  
Surface Tension ◽  
Selective Laser Melting ◽  
Single Layer ◽  
Liquid Interface ◽  
Morphological Development ◽  
Eutectic Alloys ◽  
Laser Melting ◽  
Submicron Scale ◽  
Solid Liquid Interface ◽  
Solid Liquid

In this paper, single-layer and bulk 316 L selective laser melting (SLM) experiments were conducted, fine submicron-scale geometric symmetrical cellular (hexagonal, pentagonal and square), elongated cellular and bands solidification morphologies were found in the laser-melt top surface. Meanwhile, morphological developed sub-grain patterns with quasi-hexagonal cellular, elongated cellular and bands structures (size ~1 μm) coexisting inside one single macro-solidified grain were also identified. This demonstrated the transitions from quasi-hexagonal-cells to elongated cells/bands, and transitions reverse, occurred in the whole bulk under some circumstances during SLM. Based on the experimental realities, these morphologies are formed by the local convection and Bénard instabilities in front of the solid/liquid interface (so-called mushy zones) affected by intricate temperature and surface tension gradients. Quasi-hexagonal cellular convective fields are then superimposed on macro-grain solidification to form the sub-grain patterns and micro-segregations. This explanation seems reasonable and is unifying as it can be expanded to other eutectic alloys with face center cubic (FCC) prevenient phase prepared by SLM, e.g., the Al-Si and Co-Cr-Mo systems.

Solid–Liquid Diffusion and Phase Growth Kinetics in Mg-Ca Binary System

2015 ◽  
Vol 816 ◽  
pp. 418-423
Author(s):  
Xin Li ◽  
Bin Jiang ◽  
Hong Yang ◽  
Xiang Sheng Xia ◽  
Jia Hong Dai ◽  
...  
Keyword(s):  
Activation Energy ◽  
Diffusion Layer ◽  
Diffusion Mechanism ◽  
Dendritic Structure ◽  
Diffusion Time ◽  
Diffusion Couples ◽  
Phase Growth ◽  
Liquid Diffusion ◽  
Solid Liquid ◽  
Exponential Relation

The solid–liquid diffusion between Mg and Mg-10 at.% Ca alloy was studied at a temperature range of 570°C to 630°C for 10, 20, 30min, respectively. Only one compound, Mg2Ca, was observed in the diffusion couples. As the diffusion time increased, the dendritic structure of the diffusion layer became coarser. The thickness of the diffusion layer had an exponential relation to the experimental temperature. The Mg2Ca phase was observed to follow parabolic growth with diffusion time, which suggested that the growth of the Mg2Ca phase was controlled by diffusion mechanism. The activation energy was determined to be 111.28 kJ/mol.

scholarly journals Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3609 ◽  
Author(s):  
Balázs Illés ◽  
Tamás Hurtony ◽  
Olivér Krammer ◽  
Bálint Medgyes ◽  
Karel Dušek ◽  
...  
Keyword(s):  
Thin Films ◽  
Layer Thickness ◽  
Layer Structure ◽  
Intermetallic Layer ◽  
Copper Substrate ◽  
Substrate Roughness ◽  
Cu Substrate ◽  
Layer Deposition ◽  
Cu Substrates ◽  
Effect Of Copper

The effect of copper substrate roughness and tin layer thickness were investigated on whisker development in the case of Sn thin-films. Sn was vacuum-evaporated onto both unpolished and mechanically polished Cu substrates with 1 µm and 2 μm average layer thicknesses. The samples were stored in room conditions for 60 days. The considerable stress—developed by the rapid intermetallic layer formation—resulted in intensive whisker formation, even in some days after the layer deposition. The developed whiskers and the layer structure underneath them were investigated with both scanning electron microscopy and ion microscopy. The Sn thin-film deposited onto unpolished Cu substrate produced less but longer whiskers than that deposited onto polished Cu substrate. This phenomenon might be explained by the dependence of IML formation on the surface roughness of substrates. The formation of IML wedges is more likely on rougher Cu substrates than on polished ones. Furthermore, it was found that with the decrease of layer thickness, the development of nodule type whiskers increases due to the easier diffusion of other atoms into the whisker bodies.

Sign in / Sign up

Export Citation Format

Share Document