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![2-1) Binary phase diagram of Ag-Zn system [22].](profile/Aloke-Paul/publication/242523945/figure/fig11/AS:669490522103822@1536630387803/Fig-32-1-Binary-phase-diagram-of-Ag-Zn-system-22.png)
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Replacement of copper( i ) ions by silver( i ) improves the solid-state photoluminescence properties.
This paper describes the technical details of the development of a high-power solid-state amplifier for Brookhaven Laboratory. The amplifier must withstand short duration events of 100% full-power reflection, and also must guarantee delivery of continuous power into any load impedance at any angle.
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... This voiding could be related to the Kirkendall effect, which was attributed to the unequal diffusion rates of Cu and Sn in the IMC [29] and impurity segregation [30][31][32][33][34]. It is generally believed that Cu is the dominant diffusing species in Cu 3 Sn, a larger diffusion flux of Cu would occur from the Cu substrate [35][36][37]. If the vacancies, left by the diffusing-out of Cu atoms, cannot be occupied, they would gather to form new micro-voids with impurity [30][31][32][33][34]. Consequently, if the unequal diffusion rate between Cu and Sn exists, the voids would increase continuously. ...
The use of scaled-down micro-bumps in miniaturized consumer electronic products has led to the easy realization of full intermetallic solder bumps owing to the completion of the wetting layer. However, the direct contact of the intermetallic compounds (IMCs) with the adhesion layer may pose serious reliability concerns. In this study, the terminal reaction of the Ti adhesion layer with Cu–Sn IMCs was investigated by aging the micro-bumps at 200 °C. Although all of the micro-bumps transformed into intermetallic structures after aging, they exhibited a strong attachment to the Ti adhesion layer, which differs significantly from the Cr system where spalling of IMCs occurred during the solid-state reaction. Moreover, the difference in the diffusion rates between Cu and Sn might have induced void formation during aging. These voids progressed to the center of the bump through the depleting Cu layer. However, they neither affected the attachment between the IMCs and the adhesion layer nor reduced the strength of the bumps. In conclusion, the IMCs demonstrated better adhesive behavior with the Ti adhesion layer when compared to Cr, which has been used in previous studies.
... Prenons l'exemple d'un système théorique A-B, avec la présence d'un IMC β et une solubilité mutuelle des métaux purs A et B considérée comme nulle (figure 1.5-a). [37] Ainsi, dans un couple binaire, chaque composé stable est susceptible d'apparaître et de croître sous forme de couches planes dans la zone d'interdiffusion 2 . Cette succession reprend l'apparition des phases dans le diagramme d'équilibre, comme dans l'exemple du couple de diffusion Cu-Sn (figure 1.6) où se développent les IMC Cu 3 Sn et Cu 6 Sn 5 . ...
... L'ajout de Ni dans le couple de diffusion réduit la taille des grains de Cu 6 Sn 5 . Dans ce cas, la vitesse de croissance de Cu 6 Sn 5 augmente, ce qui semble confirmer que Sn diffuse principalement dans Cu 6 Sn 5 via les joints de grain [37,67]. Les études ont aussi montré une apparition séquentielle des composés intermétalliques : la couche de Cu 6 Sn 5 se développe avant la couche de Cu 3 Sn [68], et ce dernier n'apparaît pas à des température inférieures à 150°C [39,69]. ...
Une technologie de soudage par diffusion à l'état solide, dite par thermodiffusion, a été développée pour miniaturiser les circuits imprimés. Une configuration prometteuse dans laquelle des dépôts d'or et d'étain sont respectivement déposé sur chacune des deux couches de cuivre à assembler a été retenue. La thermodffusion conduit à la formation de composés intermétalliques formant le joint. La microstructure du joint dépend des épaisseurs respectives des métaux d'apport et du chargement thermique (temps - température). La microstructure obtenue en fin de procédé contrôle la tenue mécanique du joint. L'objectif de ce travail est de comprendre l'évolution de la microstructure au cours du cycle thermique et son influence sur la tenue mécanique afin de garantir une fiabilité des interconnexions.Les évolutions de microstructure ont été caractérisées le long de cycles thermiques à 200 et 240°C à partir d'une structure dite optimisée de 1,5 µm d'or et 3 µm d'étain. Les différents composés intermétalliques présents dans les joints ont été identifiés, ainsi que les différentes étapes de diffusion et leurs cinétiques. Lors du maintien en température, des composés binaires se forment rapidement, puis sont remplacés progressivement par un composé ternaire nommé phase B ; dans une dernière étape, la phase B commence à être consommée par des composés binaires riches en cuivre (Cu3Sn, AuCu3 ou AuCu). Un essai in situ sous MET a permis d'observer une diminution des vides de Kirkendall lors de la consommation de la phase B par les composés binaires.Des essais de nanoindentation ont été réalisés pour mesurer les propriétés mécaniques des différentes composés intermétalliques, dont la phase B (avec un module d'Young de l'ordre de 130 GPa et une dureté de 8 GPa). Des essais de cisaillement et de pelage associées à aux analyses des faciès de rupture et à un essai de traction in situ sous MEB a permis d'identifier les mécanismes de rupture. L'interface entre le cuivre et la phase B peut être fragilisée par la présence de cavités et d'intermétalliques nanométriques, ce qui en fait une zone critique.
... 26 The Cu− Sn phase diagram shows two low-temperature IMCs formed through interdiffusion: an orthorhombic ε-Cu 3 Sn and a monoclinic η-Cu 6 Sn 5 . 27,28 Many experimental results on binary Cu−Sn diffusion couples at low temperatures find that these two phases develop at Cu−Sn interfaces. 29 A number of measured and derived Cu−Sn interdiffusion concentration profiles from the literature appear much the same as the EDS profile near the Cu−Sn interface in Figure 2c, see for example Kumar et al. 30 Another feature of many of these studies of Cu−Sn interdiffusion is the development of microvoids at the interface, which are attributed to the faster diffusion of Cu into Sn than Sn into Cu and the IMC layers. ...
... % according to various sources), to limit Cu outdiffusion and create a stable phase of (Cu, Ni) 6 Sn 5 at room temperature. 27,38 3.1.2. Cu-Plated and Ag-Capped. ...
... One is the interfacial reaction growth, and the other is the ripening growth by annexation of neighboring grains. There are chemical reactions for the growth and transformation of interfacial IMCs in Cu/Sn/Cu microbumps [36,37]. ...
The thickness of the solder, for Cu/Sn/Cu microbumps with dimensions of tens of microns or even a few microns (such as 40 µm, 15 µm, 10 µm, and 6 µm), can have a significant effect on the interfacial transfer and the performance. During the reflow stage, it was found that the grains of Cu6Sn5 showed “staggered growth” phenomenon in some areas of the microbumps with the solder thickness of 6 µm and the thickness of intermetallic compounds’ (IMCs) layer grew the fastest; that the second fastest growth of 40 µm; that the third fastest growth of 15 µm, and that the slowest growth of 10 µm. After thermal aging at 160 °C for 80 h, the thickness of the IMC layer in descending order was the microbumps with the solder thickness of 15 µm, 10 µm, 40 µm, and 6 µm. These results were caused by the difference in the element concentration. In addition, there were four main components in the microbumps: Cu, Sn, Cu6Sn5, and Cu3Sn. The hardness of Cu and Sn was about 1.37 ± 0.3 Gpa and 0.13 ± 0.03 Gpa, respectively. And the hardness of Cu6Sn5 and Cu3Sn was about 6.7 ± 0.3 Gpa and 6.2 ± 0.4 Gpa, respectively. The nanoindentation hardness analysis showed a general increase in the hardness of the microbumps after thermal aging for 80 h, compared with that after reflow. And the thinner the solder thickness was, the more obvious the hardness improvement was.
... where C Al − and C Al + are the concentration of Al in the unaffected left (superalloy) and right-hand (bond coat) side of the diffusion couple. The molar volumes of the phases are taken from Ref. [55]. Once the Matano plane is located, as shown in Fig. 19(a), the loss of Al from the bond coat can be estimated from the area defined by ∫ xm x+ C Al dx, which is equal to the gain of Al by the superalloy as defined by the area ∫ ...
The addition of Pt to the β-NiAl bond coat enhances the service life of the turbine blade in jet engine application. However, it increases the growth of the unwanted precipitate containing an interdiffusion zone between the bond coat and superalloy. The role of Pd and Ir addition is examined in this study by comparing the growth of the interdiffusion zone without compromising the thermal cycle resistance of the oxide layer. The oxide layers on all the bond coats grow with duplex morphology. Ni and Ir-containing precipitates are found inside α-Al2O3 oxide layer on Ir-containing bond coats. The microstructural evolution of the interdiffusion zone is explained with the help of the diffusion path. The addition of Ir is found to decrease the growth of the interdiffusion zone significantly compared to the Pt containing bond coat without compromising the thermal cycle resistance of the oxide layer, which could be considered as an important addition in next-generation turbine blades.
... solder the formation of two intermetallic phases becomes possible: Cu3Sn, also known as thephase, and Cu6Sn5, also known as the -phase. The growth kinetics of the phase was identified as predominant by several experimental and theoretical studies [7,8,9]. Thus, further growth of only the phase is considered. ...
... Hence, there is a vacancy flux of opposite sign and equal in magnitude to the total flux of Cu and of Sn. Differences of these fluxes result in the accumulation of vacancies and, therefore, in the formation of Kirkendall voids [7]. The diffusivity of Cu is greater than of Sn. ...
An analytical model of electromigration and stress affected kinetics of a chemical reaction is investigated based on the notion of the chemical affinity tensor within the small strain approximation. Effects of stresses are accounted for through their influence on the chemical affinity tensor on which the reaction front velocity depends. Electromigration is considered as an additional summand in the total flux of the diffusive constituents. The Mean-Time-To-Failure (MTTF) is estimated based on Black's equation. Then the critical thickness of the IMC layer is calculated and a dimensionless parameter, which characterizes the accumulation of vacancies due to electromigration enhanced diffusion is proposed.
... This phenomenon is only possible if diffusion occurs by an exchange mechanism [34]. An important consideration from the Kirkendall effect is the presence of voids formed during the diffusion process [39]. These porosities occur due to the difference in the diffusion rate of the two alloy species in an attempt to restore equilibrium. ...
The use of shape memory alloys for micro-actuators constitutes a field of application in which copper–aluminum-based alloys find their usefulness because they can reach higher activation temperatures and are easier to produce than titanium-based alloys, particularly by the method proposed in this work. SMA tapes are a two-dimensional structure that offers many design options such as stamping, punching, and deep drawing, but they are also suitable for laser cutting, engraving, stamping, and EDM machining. This work has been made to study the manufacture of copper-based shape memory alloys (SMAs) using the cold co-rolling process also called the cold-roll bonding (CRB) process. In this process, a thin metal sandwich can be produced with a rolling machine. This sandwich consists of layers of CuNiBe master alloy and Al. During the rolling phase, the sandwich has no shape memory effect (SME) or superelastic effect (SE), so thin strips can be easily produced. After the rolling phase, the sandwich is subjected to a complex heat treatment to gain the SME. To validate this process to produce Cu-based SMAs, several alloys with different CuAlNiBe compositions have been tested. The SMAs obtained were characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The martensitic transformation was studied by Differential Scanning Calorimetry (DSC) and SME and SE were studied by three-point bending tests. This work shows that the CRB is a good process for making a wide variety of Cu-based SMA ribbons.
... In most cases, the reaction is not a single occurrence, but a mixed control at the same time. The beginning of reduction is controlled by phase interface chemical reaction, the reduction process is controlled alternately by diffusion and chemical reaction under the influence of reduction conditions, and the later stage of reduction is mainly controlled by diffusion [61][62][63]. ...
The global warming promotes the steel industry to replace part of coke by injecting hydrogen-rich fuel into the blast furnace to reduce CO2 emissions and energy consumption. In this paper, the injected hydrogen-rich fuels and effects of hydrogen-rich smelting on burden reduction and property evolution were introduced, and the hot events related to hydrogen metallurgy were summarized. Increasing hydrogen content changes the thermodynamic and kinetic conditions of chemical reactions, changing the reduction behaviour of iron oxides and affecting the burden properties evolution and soft melting behaviour. Correspondingly the coke solution loss alters due to more H2O existence. In addition, the temperature and gas flow distribution are altered, affecting the iron oxide reduction rate and efficiency of blast furnace operation process. At present, some hydrogen metallurgy projects have been launched, making expected progress, which provides reference and thinking for the large-scale industrial application of hydrogen in blast furnace.
... This may lead to a decrease of the reliability of the joint. In addition, intense diffusion of Cu (from the pad) or Sn atoms through the IMC may lead to void formation due to the Kirkendall effect, see, e.g., Paul [2004]; Dybkov [2010]. ...
... The positive deviation of the molar volume leads to an expansion of the diffusion couple. Considering a linear expansion, we can calculate this from [39] : ...
... The plus and minus signs correspond to the positive and negative deviation leading to expansion or shrinkage of the diffusion couple. It should be noted here that x is also equal to the difference in location of the Matano planes when calculated considering the concentration profiles of Fe and Ga because of non-ideality of the molar volume variation [39] . Our analysis for the Fe/Fe-24 Ga diffusion couple with the interdiffusion zone length ~175 μm indicates that we have an expansion of only 0.2 μm due to such a small positive deviation of molar volume from Vegard's law in this system. ...
