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Transversal problems such as crowding and crossbite are one of the most common problems dealt with in early orthodontic treatments. Early correction of these problems may ease or even eliminate the future need for treatment. This paper presents the management of 2 cases with transverse discrepancy using the Ni-Ti Memory Leaf Expander----a new compliance-free slow maxillary expansion appliance. The total treatment time for both cases was 9 months. In both cases, the inter-canine, inter-premolar, and inter-molar distances, as well as the arch length, have all increased. [ABSTRACT FROM AUTHOR]

Thermoelectric properties and phase evolution have been studied in biphasic Ti-Ni-Sn materials containing full-Heusler TiNi2Sn embedded within half-Heusler thermoelectric TiNiSn. Materials, prepared by levitation induction melting followed by annealing, were of the nominal starting composition of TiNi1+xSn, with x between 0.00 and 0.25. Phases and microstructure were determined using synchrotron X-ray diffraction and optical and electron microscopy. The full-Heusler phase is observed to be semi-coherent with the half-Heusler majority phase. Differential thermal analysis was performed to determine melting temperatures of the end-member compounds. The thermal conductivity is reduced with the introduction of a dispersed, full-Heusler phase within the half-Heusler material. This leads to an increased thermoelectric figure of merit, ZT, from 0.35 for the stoichiometric compound to 0.44 for TiNi1.15Sn. Beyond x=0.15 ZT decreases due to a rise in thermal conductivity. Density functional theory calculations using hybrid functionals were performed to determine band alignments between the half- and full-Heusler compounds, as well as comparative energies of formation. The hybrid functional band structure of TiNiSn is presented as well. [ABSTRACT FROM AUTHOR]

Systematic experimental work was carried out to understand the growth kinetics of Ni3Sn4 at the Sn–3.5Ag solder/Ni interface. Sn–3.5%Ag solder was reflowed over Ni metallization at 240 °C for 0.5 min and solid-state aging was carried out at 150–200 °C, for different times ranging from 0 to 400 h. Cross-sectional studies of interfaces have been conducted by scanning electron microscopy and energy dispersive x ray. The growth exponent n for Ni3Sn4 was found to be about 0.5, which indicates that it grows by a diffusion-controlled process even at a very high temperature near to the melting point of the SnAg solder. The activation energy for the growth of Ni3Sn4 was determined to be 16 kJ/mol. [ABSTRACT FROM AUTHOR]

Abstract A nanostructured Ni Sn alloy/multi-walled carbon nanotube (MWCNT) composite was successfully synthesized for highly reversible sodium and hydrogen ions storage by using an electrochemical deposition process on porous Cu foam. The surface morphology of the resulting Ni Sn alloy/MWCNT nanocomposite was characterized using a field-emission scanning electron microscope, indicating the formation of sphere-like Ni Sn alloy nanoparticles with an average size of 190 nm. On the other hand, X-ray diffraction analysis, energy dispersive and Fourier transform infrared spectroscopies were employed to determine the crystalline structure, elemental surface and chemical composition of the nanocomposite electrode. The initial sodium discharge capacity of the electrode was maximized at ∼550 mAh g−1 under the current density of 1000 mA g−1, and a high hydrogen discharge capacity of 5200 mAh g−1 was obtained at 1100 mA g−1 after 20 cycles. A comprehensive comparison between the sodium and hydrogen ions capacities in this study and those of the literature for different materials and structures was also performed. Accordingly, the resulting nanocomposite electrode with dual capacity may offer promising applications in both sodium-ion battery and hydrogen storage. Graphical abstract Image 1 Highlights • Ni Sn alloy/MWCNT nanocomposite was synthesized on Cu foam using electrodeposition. • Sodium and hydrogen ions storage of the electrode was investigated by chronopotentiometry. • High sodium and hydrogen discharge capacities of ∼550 and 5200 mAh g−1 were obtained. • Sodium capacity stabilized at 200 mAh g−1 under a current density of 1000 mA g−1. • Enhanced Coulombic efficiency of 98% was achieved for the nanocomposite electrode. [ABSTRACT FROM AUTHOR]

Abstract A coordinate change of conjugation twin boundaries in Ni-Mn-Sn single crystals is studied with scanning electron microscopy. During mechanical training, the so-called orthogonal shear process initiates variant reorientation leading to the replacement of the main with conjugation type I twin boundaries. The experimental data demonstrate that highly organized redistribution of adjacent variants, in the neighboring areas, is then critical for the removal of conjugation boundaries by coordinated secondary twinning. In addition, a more complex variant reorientation mechanism is uncovered and it is found to allow for transitioning between non-conjugate twin systems. The proposed mechanism appears consistent with the orientation relationship between austenite and martensite, which is controlled by a shear deformation and martensite crystallography leading to an equal distribution of martensitic variants. This contribution complements the existing theory of martensite crystallography providing direct evidence for the general nature of the orthogonal shear process as a first step in variant reorganization during mechanical training of martensite. Highlights • Removal of type II twins and type II inter-plate boundaries by a coordinate change of conjugate twin planes. • Orthogonal shear process affects the neighboring colonies allowing transition between non-conjugated twin systems. • Coordinated secondary twinning generates shear-induced rotation reducing the number of orientations from 24 to 12. • All rotations during training procedure are symmetric with respect to austenite orientation. [ABSTRACT FROM AUTHOR]

Abstract Avoiding Sn segregation is vital to produce high performance large scale Cu-Ni-Sn alloys. In this work a low Sn-containing Cu-9Ni-2.5Sn-1.5Al-0.5Si alloy with high strength and ductility was developed by substituting Sn in Cu-Ni-Sn alloy with Al and Si. The results show that Si leads to a bimodal structure, which has coarse unrecrystallization regions with a plenty of <111> fiber texture and fine equaixed recrystallization grains. Such a bimodal structure results into good mechanical properties showing a high tensile strength of 861 MPa and a large elongation of 18%, which is comparable to Cu-15Ni-8Sn alloy. The strengthening effects are ascribed to precipitate strengthening, grain refining and twin boundary strengthening in the fine equaixed recrystallization grains and texture strengthening in the coarse unrecrystallization regions. [ABSTRACT FROM AUTHOR]

The reaction within Ni/Sn/Cu microjoints has been investigated with a 10 μm initial thickness of Sn so that Sn was quickly consumed in the early stage of the reaction, transforming the joints into full intermetallic joints. Accordingly, the emphasis of the present study is on the materials interactions in such full intermetallic joints. Ni/Sn/Cu sandwiches were prepared by thermal compression bonding. High-temperature storage tests were conducted at 150°C, 180°C, and 200°C for different time periods. The hardness and Young's modulus of the intermetallic joints were measured using nanoindentation. The key finding of this study is that, once Sn was exhausted, the originally planar (Cu,Ni)3Sn grew preferably along the grain boundary of (Cu,Ni)6Sn5, creating a highly nonuniform (Cu,Ni)3Sn growth front. Both the hardness and elastic modulus increased with the Ni concentration in the intermetallics. [ABSTRACT FROM AUTHOR]

Under the simultaneous influence of volume shrinkage and surface solder diffusion, the microstructural evolution in Ni/Sn/Ni microjoints exhibits a conformable tendency among different joint sizes. This conformable tendency is the necking of the Sn layer and the initiation of voids which occur only near the periphery of the Sn layer. The reasons for this joint-size dependency have been theoretically evaluated and proposed in this study. This dependency remains applicable until the Ni3Sn4 layers growing in opposite directions impinge on each other. Afterward, microvoids are able to form everywhere along the centerline of the joints. It is hypothesized that the electrical and mechanical performance of microjoints is significantly related to the microstructures in these joints. With the help of the joint-size dependency proposed in this study, it is expected that the dimensional design of microjoints is capable of being optimized to assure high reliability. [ABSTRACT FROM AUTHOR]

In this paper, novel three dimensional hierarchical porous Sn-Ni (3D-HP Sn-Ni) alloys were investigated as a promising anode for high-performance Li ion batteries (LIBs), which was fabricated by pulse electrodeposition of mesoporous Sn-Ni alloy made of ultrafine nanoparticles on the 3D nanoporous copper substrate from chemical dealloying of as-cast Al 55 Cu 45 (at.%) alloy slices in the HCl solution. The results show that the as-obtained 3D-HP Sn-Ni alloys are typically characteristic of open, bicontinuous, interpenetrating bimodal pore size distribution comprising large-sized (hundreds of nm) ligament-channel network architecture with highly porous channel walls (several nm). Compared to the two dimensional nanoporous Sn-Ni (2D-NP Sn-Ni) thin films, the 3D-HP Sn-Ni alloys as anode for LIBs show superior cycling stability with reversible specific capacity of 0.25 mAh cm −2 and coulombic efficiency of more than 95% up to 200 cycles. Moreover, the reversible capacity as high as 0.22 mAh cm −2 can be achieved even after a series of high-rate charge–discharge cyclings. The satisfactory electrochemical properties can be mainly ascribed to the unique 3D hierarchical porous structure, large contact surface area between active material and electrolyte, as well as good buffer effect of inactive component, which is greatly beneficial to alleviate the huge volume variation, enhance the loading mass of active material, shorten the Li + migration distance and improve the electron conductivity. We believe that this present work can provide a promising anode candidate towards practical application of high-performance LIBs. [ABSTRACT FROM AUTHOR]

Physical properties of Ni 3 Sn x intermetallic compounds as well as the interfacial properties of Ni/Ni 3 Sn interface were investigated by first-principles calculations for studying the crack initiation behavior and mechanism of the novel Nickel-Tin TLPS bonding layer. The results indicated that, for Ni and Ni 3 Sn x intermetallic compounds, Ni 3 Sn 4 intermetallic compound shows the smallest deformation resistance, the largest brittleness and strongest micro-cracks initiation tendency because of the largest average bond length, the biggest crystal asymmetry and the most complex bonding characteristic, so it will be cracking preferentially in all of the Ni 3 Sn x intermetallic compounds under the stress condition. For the Ni/Ni 3 Sn interfaces, Ni (111)/Ni 3 Sn (111) interface with OT stacking sequence shows the weakest interfacial bonding strength with adhesion energy of 3.11 J/m 2 , and it will crack at layer 1′-1 with only 12% imposed strain, so it can be considered as the weakest interface under the stress condition in all of the Ni/Ni 3 Sn interfaces. [ABSTRACT FROM AUTHOR]

The structure, phase transitions, magnetocaloric effect, and exchange bias effect in Mn 49 Ni 42- x Co x Sn 9 ( x  = 0, 1, 3 and 5) ferromagnetic shape memory alloys have been systematically investigated. X-ray diffraction results measured at room temperature reveal that Mn 49 Ni 42- x Co x Sn 9 alloys with x  = 0, 1 present martensite structure, and Mn 49 Ni 42- x Co x Sn 9 alloys with x  = 3, 5 exhibit mixture phases of both martensite and austenite. The martensitic transformation and exchange bias field ( H EB ) are very sensitive to the Co content. In addition, large positive magnetic entropy changes were observed in these alloys due to the magnetic-field-induced transition from the paramagnetic martensitic phase to the ferromagnetic austenitic phase, and a large effective refrigeration capacity of 230.8 J/kg was obtained under the magnetic field change of 70 kOe in Mn 49 Ni 37 Co 5 Sn 9 alloy. We realized a continuous tuning of the H EB from 534.7 Oe to 1113.0 Oe after field cooling in presence of 10 kOe. [ABSTRACT FROM AUTHOR]

For high-temperature-resistant packaging of new generation power chip, a chip packaging simulation structure of Ni/Ni-Sn/Ni was bonded by a transient liquid-phase sintering process. High-temperature aging experiments were carried out to investigate joint heat stability. The microstructural evolution and mechanism during aging, and mechanical properties after aging were analyzed. The results show that the 30Ni-70Sn bonding layer as-bonded at 340°C for 240 min is mainly composed of Ni3Sn4 and residual Ni particles. When aged at 350°C, because of the difficulty of nucleation for Ni3Sn and quite slow growth of Ni3Sn2, the bonding layer is stable and the strength of that doesn’t change obviously with aging time. When aging temperature increased to 500°C, however, the residual Ni particles were gradually dissolved and the bonding layer formed a stable structure with dominated Ni3Sn2 after 36 h. Meanwhile, due to the volume shrinkage (4.43%) from Ni3Sn2 formation, a number of voids were formed. The shear strength shows an increase, resulting from Ni3Sn2 formation, but then it decreases slightly caused by voids. After aging at 500°C for 100 h, shear strength is still maintained at 29.6 MPa. In addition, the mechanism of void formation was analyzed and microstructural evolution model was also established. [ABSTRACT FROM AUTHOR]

C u 2 NiSn S 4 is a non-toxic earth abundant material and a promising quaternary semiconductor compound. Due to its optimum direct band gap, it has been considered as a suitable absorber material for photovoltaic cells. It is a conspicuous and suitable class of material for the fabrication of low cost and high efficiency thin film devices. This paper presents numerical modeling for the efficiency enhancement of C u 2 NiSn S 4 based experimental photovoltaic cells. In this work, the experimental cell results were reproduced in the SCAPS software. These simulated results are validated and compared with the experimental reference cell. C u 2 O as the hole transport layer is also proposed for further efficiency enhancement of the photovoltaic cell. After optimization of cell parameters, the power conversion efficiency of an optimized device is increased up to 4.60%. By applying the hole transport layer and analyzing the minority carrier life time, the conversion efficiency increases up to 10.35%. This work presents a novel concept in numerical modeling by analyzing the experimental solar cell, which will categorically offer new directions for the fabrication of high efficiency photovoltaic devices. [ABSTRACT FROM AUTHOR]

Broad ranges of cooling rates ( T ˙) 0.8–30.5 and 0.4–5.0 K s−1 are attained during directional solidification of eutectic Sn–0.2 wt% Ni and hypereutectic Sn–0.5 wt% Ni alloys, respectively. A reverse high cooling rate cell‐to‐dendrite transition occurs for the eutectic composition and a transition from high cooling rate cells to plate like cells for the hypereutectic alloy. High cooling rate β‐Sn cells are associated with cooling rates >5.5 and >2.7 K s−1 for eutectic and hypereutectic compositions, respectively. A processing diagram, relating the ‘ T ˙–Ni content’ space with the microstructural morphology, is proposed. A combination of plate like cells and plate NiSn4 eutectic phase results in higher ductility. [ABSTRACT FROM AUTHOR]

In this work, Cu-15Ni-8Sn components were manufactured by selective laser melting (SLM) with a near full density of about 99.4%. The microstructures and phase precipitation of the as-fabricated Cu-15Ni-8Sn alloy were characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), electron back-scattered diffraction (EBSD), and transmission electron microscope (TEM). It was demonstrated that the as-fabricated Cu-15Ni-8Sn alloy shows α-phase with γ-precipitates by XRD and TEM. The size of the grains of α-phase is in the range of 5~20 μm with random orientation distribution. The γ-precipitate is a Sn- and Ni-rich phase distributed dispersedly in matrix and accumulatively in grain boundary. The as-fabricated Cu-15Ni-8Sn alloy exhibited yield strength of 522 MPa, ultimate tensile strength of 653 MPa, and elongation of 17%. The excellent mechanical performance of the as-fabricated Cu-15Ni-8Sn alloy is caused by the local laser melting mode including rapid cooling rate and reduplicative fusing from the subsequent layer melting, which leads to refined grains and limited Sn segregation in micron-size within the matrix. [ABSTRACT FROM AUTHOR]

Spinodal decomposition in Cu-9.4at%Ni-3.1at%Sn alloy was elucidated with the new insight from the experimental EXAFS analysis supported by ab initio total energy calculations suggesting the strong influence of the first near-neighbour atoms. Enthalpy of mixing was calculated for all crystallographically unique first near-neighbour configurations and finally an average positive enthalpy of mixing of 1604 J/mol was obtained. Combination of ab initio results, XRD and EXAFS analysis indicate that one of the daughter phase becomes rich in Ni and Sn than the other phase; in contrary to the earlier proposition that Cu/Ni ratio remains constant in both daughter phases. It is also shown that the present thermodynamic description requires further refinement to extend the miscibility gap towards lower Ni content in Cu-Ni-Sn system. [ABSTRACT FROM AUTHOR]

Copper-Nickel-Tin (Cu-Ni-Sn) spinodally decomposable alloy of composition Cu-7Ni-4Sn was prepared by using sand casting process. The specimens required for microscopic examination, micro-hardness and wear tests were prepared from heat treated (homogenization, solution and ageing) cast rods. The microscopic examination results revealed that the as-cast dendrite structure was disappeared during the homogenization, solution and ageing processes and forms grains of various sizes with respect to ageing time. The hardness of the alloy was increased from 206 HV at solution treated condition to 235 HV at four hours of ageing. By using pin-on-disc wear tester in dry sliding condition an adhesive wear test was conducted as per L9 orthogonal array by taking parameters of applied load, sliding speed and ageing time. An optimum level of parameter for each case was determined through S/N ratio investigation by considering "smaller-the-better". From this investigation, it was found that the parameter ageing time was the dominant as compared to other two parameters. The significant parameter that affect the response was indicated by the results obtained from ANOVA and these results were agreed with S/N analysis. The developed linear regression equation was validated through confirmation experiments. The wear mechanism was observed on worn out surfaces by selecting appropriate specimens considering applied load and sliding speed for both normal and optimum parameter specimens using scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Utilizing five groups of bulk diffusion couples together with electron probe microanalysis technique, the composition-dependent ternary interdiffusion coefficients in fcc Cu–Ni–Sn alloys at 1023 K were determined via the Whittle and Green method. The presently obtained interdiffusion coefficients at 1023 K as well as our previously measured ones at 1073 K were combined with the slightly modified thermodynamic descriptions of the fcc Cu–Ni–Sn phase to explore atomic mobilities of Cu, Ni and Sn in fcc Cu–Ni–Sn alloys within the CALPHAD framework. In order to be consistent with the thermodynamic description, atomic mobilities in binary fcc Ni–Sn alloys were re-evaluated in the present work. The quality of the assessed kinetic characteristics was confirmed by the comprehensive comparisons between various model-predicted diffusion behaviors and the experimental ones, including concentration profiles and diffusion paths. [ABSTRACT FROM AUTHOR]

Direct solution coating technique has emerged as a promising economically viable process for earth abundant chalcogenide absorber materials for photovoltaic applications. Here, direct ethanol based dip coating of earth abundant Cu 2 NiSnS 4 (CNTS) films on soda lime glass (SLG), molybdenum coated glass (Mo), and fluorine doped tin oxide coated glass (FTO) substrates is investigated. The structural and morphological properties of pre-annealed and sulfurized CNTS films coated on SLG, FTO, and Mo substrates are reported. The influence of dipping cycles on composition and optoelectronic properties of pre-annealed and sulfurized CNTS films deposited on SLG substrate is presented. Energy dispersive spectroscopy (EDS) and X-ray fluorescence (XRF) analysis reveal how changes in thickness and elemental composition affect morphology and optoelectronic properties. The obtained absorption coefficient, optical bandgap, resistivity and mobility of pre - annealed and sulfurized films are found to be 10 4 cm −1 , 1.5 eV, 0.48 Ωcm, 3.4 cm 2 /Vs and 10 4 cm −1 , 1.29 eV, 0.14 Ωcm, 11.0 cm 2 /Vs, respectively. These properties are well suited for photovoltaic applications and lead to the conclusion that the direct ethanol based dip coating can be an alternative economically viable process for the fabrication of earth abundant CNTS absorber layers for thin film solar cells. [ABSTRACT FROM AUTHOR]

In situ digital image correlation (DIC) and in situ X-ray diffraction (XRD) are applied to investigate the effect of temperature on martensitic transformation and plastic deformation in superelastic NiTi shape memory alloy. Via in situ DIC, two well-known deformation modes of NiTi are identified at various temperatures: (A) localized forward and reverse transformations with little residual strain (< 1%); (B) localized forward transformation and homogenous reverse transformation with considerable residual strain (> 1%). As temperature increases from 25 °C to 120 °C, the mechanical response of NiTi gradually transits from Type A to Type B. We verify that plastic strain accumulates concurrently as the traverse of the front of localized deformation band. Via in situ XRD observation, we conclude that it is material plasticity rather than retained martensite that plays a dominant role in the irreversibility of NiTi. The experimental results provide both macroscopic and lattice level scenarios to understand the temperature dependence of complicated thermomechanical coupling and plasticity in superelastic NiTi. [ABSTRACT FROM AUTHOR]

Ni–Sn alloy intermetallic coatings with different Sn contents, were electrodeposited on Vanadis 23 steel substrates. Structural and chemical characterisation of these coatings was performed by x-ray diffraction, scanning electron microscopy and electron dispersive x-ray analysis. The as-plated Ni–Sn coatings were found to consist of a crystalline Ni solid solution with dispersed Ni–Sn intermetallic phases, whereas in certain cases bulk intermetallic coatings were obtained. The addition of Sn as an alloying element into electrolytic Ni coatings led to a significant increase of hardness and Young’s modulus of these coatings. In addition, the effect of a post-deposition heat treatment at 400°C for 1 h on the microstructure and mechanical characteristics of these electrolytic Ni–Sn alloy coatings was investigated. [ABSTRACT FROM AUTHOR]

The effects of Cu concentration ( x ) on the interfacial microstructure between a molten Sn-3Ag- x Cu alloy and an electrolytic Au/Ni/Cu multilayer and its mechanical reliability were investigated via transmission electron microscopy (TEM) and high-speed ball shear (HSBS) testing. The x values were 0, 0.3, 0.4, 0.5, 0.7, and 1.0 (wt%). An increase in x caused an interfacial intermetallic compound (IMC) transition from a dense (Ni,Cu) 3 Sn 4 layer ( x = 0 and 0.3) to the coexistence of (Ni,Cu) 3 Sn 4 and (Cu,Ni) 6 Sn 5 ( x = 0.4 and 0.5), and to a dense (Cu,Ni) 6 Sn 5 layer ( x = 0.7 and 1.0) after soldering reaction at 250 °C for 2 min. An increase in the reaction time enhanced the IMC growth and induced the nucleation of a (Ni,Cu) 3 Sn 4 nanolayer beneath (Cu,Ni) 6 Sn 5 in the high x case. The TEM and HSBS characterizations showed that a single, thin (Ni,Cu) 3 Sn 4 layer grown at the interface possessed better shear resistance than a single (Cu,Ni) 6 Sn 5 layer, and the presence of a dual layer structure of (Cu,Ni) 6 Sn 5 /(Ni,Cu) 3 Sn 4 substantially degraded the mechanical properties of the joint interface. These observations indicated that the Cu concentration in Sn-3Ag- x Cu alloy plays a crucial role in the interfacial reaction, which, in turn, dominates the mechanical reliability of microelectronic joints. [ABSTRACT FROM AUTHOR]

The grain morphology evolution and mechanical strength change of the intermetallic joints formed in a Ni/Sn/Cu system by the transient liquid phase (TLP) soldering at 260 °C, 300 °C and 340 °C were investigated. The grain morphology evolution of the (Cu, Ni) 6 Sn 5 intermetallic compounds (IMCs) was highly correlated with the Ni concentration gradient across the joints and strongly affected by the soldering temperatures, which was analyzed in detail from the aspect of thermodynamics. The shear strengths of the three types of intermetallic joints were 49.8 MPa, 50.3 MPa and 42.7 MPa, respectively. The correlation between the grain morphology evolution and the mechanical strength change of the intermetallic joints was revealed. [ABSTRACT FROM AUTHOR]

The microstructure evolution of Cu-15Ni-8Sn-0.8Nb alloy during prior cold deformation by rotary swaging (RS) and subsequent aging treatment was investigated. Electron back scattered diffraction (EBSD) results indicated that the deformed microstructure mainly consisted of refined and elongated grains. Discontinuous precipitates appeared at previous grain boundaries (PGBs) and shear bands after deformation of 45 pct reduction. Transmission electron microscope (TEM) studies revealed that the transformation kinetics of both DO 22 ordered phases and discontinuous precipitates were significantly accelerated by prior deformation, and the transformation from DO 22 to L1 2 ordering was suppressed to a certain degree. The maximum yield strength of the specimens with 45 pct reduction reached to about 1230 MPa after aging treatment, but the corresponding ductility was poor due to the rapid growth of discontinuous precipitates. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of the Cu-15Ni-8Sn-1.0Zn- 0.8Al-02Si alloy treated with different thermo-mechanical processes in 3.5 wt% NaCl solution was investigated by electrochemical test, electron microscopy and XPS analysis. Compared with single-stage thermo-mechanical treatment (cold rolling by 60% reduction and then aging at 450 °C for 0.5 h), the alloy with two-stage treatment (pre-aging at 400 °C for 0.5 h, cold rolling by 60% reduction and then aging at 450 °C for 0.5 h) had finer ordered precipitates and less coarse, discontinuous precipitates, resulting in better corrosion resistance performance. The corrosion product layer was mainly a mixture of Cu 2 O, CuO, NiO, Ni(OH) 2 , SnO, SnO 2 , ZnO and Al 2 O 3 , with a transition from Cu 2 O to CuO and Cu(OH) 2 occurring during the corrosion process. [ABSTRACT FROM AUTHOR]

Nanoporous networks of tin-based alloys immobilized within carbon matrices possess unique structural and compositional superiorities toward lithium-storage, and are expected to manifest improved strain-accommodation and charge-transport capabilities and thus desirable anodic performance for advanced lithium-ion batteries (LIBs). Herein, a facile and scalable hybrid aerogel-derived thermal-autoreduction route has been developed for the construction of nanoporous network of Sn Ni alloy immobilized within carbon/graphene dual matrices (Sn Ni@C/G network). When applied as an anode material for LIBs, the Sn Ni@C/G network manifests desirable lithium-storage performances in terms of specific capacities, cycle life, and rate capability. The facile aerogel-derived route and desirable Li-storage performance of the Sn Ni@C/G network facilitate its practical application as a high-capacity, long-life, and high-rate anode material for advanced LIBs. [ABSTRACT FROM AUTHOR]

Aim To assess the effect of 90°-oscillatory instrumentation with hand files on several morphological parameters (volume, surface area and uninstrumented surface) in C-shaped root canals after instrumentation using a single-file reciprocation system (Reciproc; VDW, Munich, Germany) and a Self-Adjusting File System ( SAF; ReDent Nova, Ra'anana, Israel). Methodology Twenty mandibular second molars with C-shaped canals and C1 canal configurations were divided into two groups ( n = 10) and instrumented with Reciproc and SAF instruments. A size 30 NiTi hand K-file attached to a 90°-oscillatory motion handpiece was used as final instrumentation in both groups. The specimens were scanned using micro-computed tomography after all procedures. Volume, surface area increase and uninstrumented root canal surface were analysed using CTAn software (Bruker-micro CT, Kontich, Belgium). Also, the uninstrumented root canal surface was calculated for each canal third. All values were compared between groups using the Mann-Whitney test and within groups using the Wilcoxon's signed-rank test. Results Instrumentation with Reciproc significantly increased canal volume compared with instrumentation with SAF. Additionally, the canal volumes were significantly increased after 90°-oscillatory instrumentation (between and within group comparison; ( P < 0.05)). Regarding the increase in surface area after all instrumentation protocols, statistical analysis only revealed significant differences in the within groups comparison ( P < 0.05). Reciproc and SAF instrumentation yielded an uninstrumented root canal surface of 28% and 34%, respectively, which was not significantly different ( P > 0.05). Final oscillatory instrumentation significantly reduced the uninstrumented root canal surface from 28% to 9% (Reciproc) and from 34% to 15% ( SAF; P < 0.05). The apical and middle thirds exhibited larger uninstrumented root canal surfaces after the first instrumentation that was significantly reduced after oscillatory instrumentation ( P < 0.05). Conclusions The Reciproc and SAF system were associated with similar morphological parameters after instrumentation of mandibular second molars with C-shaped canals except for a higher canal volume increase in the Reciproc group compared to the SAF. Furthermore, the final use of 90°-oscillatory instrumentation using NiTi hand files significantly decreased the uninstrumented canal walls that remained after Reciproc and SAF instrumentation. [ABSTRACT FROM AUTHOR]

Ni–Sn porous metals with different concentrations of Sn were prepared as potential current collectors for solid oxide fuel cells (SOFCs). The weight increase of these species was evaluated after heat-treatment under elevated temperatures in air for thousands of hours to evaluate the long-term oxidation resistance. Ni–Sn porous metals with 5–14 wt% of Sn exhibited excellent oxidation resistance at 600 °C, although oxidation became significant above 700 °C. Intermetallic Ni 3 Sn was formed at 600 °C due to phase transformation of the initially solid solutions of Sn in Ni in the porous metals. For the porous metal with 10 wt% of Sn, the oxidation rate constant at 600 °C in air was estimated to be 8.5 × 10 −14 g 2 cm −4 s −1 and the electrical resistivity at 600 °C was almost constant at approximately 0.02 Ω cm 2 up to an elapsed time of 1000 h. In addition, the gas diffusibility and the power-collecting ability of the porous metal were equivalent to those of a platinum mesh when applied in the cathode current collector of a SOFC operated at 600 °C. Ni–Sn porous metals with adequate contents of Sn are believed to be promising cathode current collector materials for SOFCs for operation at temperatures below 600 °C. [ABSTRACT FROM AUTHOR]

A kinetic Monte Carlo approach is used to study the influence of Cr, Fe, Al, or Mg addition on the precipitation in a Cu-Ni-Si alloy. The simulation method is based on a vacancy diffusion model. The crucial parameters of this method are the pairwise mixing energies of all contained elements which are determined by ab initio calculations. The number of dissolved atoms in equilibrium state is used to estimate the influence of Cr, Fe, Al, or Mg on the electrical conductivity. In order to estimate the influence of the alloying elements on strength ab initio calculations of misfit strain at the [ABSTRACT FROM AUTHOR]

Ni-30wt%Sn alloy powder beds were remelted using a laser beam to examine regular eutectic and anomalous eutectic growth behavior. The remelted microstructure mainly consisted of primary α-Ni dendrites and refined regular lamellar eutectic in the interdendrite space. At the top of the molten pool, the competition between primary α-Ni dendrites and the regular lamellar eutectic can be explained by the maximum interface temperature criterion. Anomalous eutectic was observed at the bottom of the molten pool. The remelting of primary α-Ni dendritic arms formed in the first laser remelting scan had an important effect on the formation of the anomalous eutectic in the second laser remelting scan. This effect led to the formation of globular α-Ni particles with similar Euler's angles in the anomalous eutectic. [ABSTRACT FROM AUTHOR]

We propose the optimal composition of a polyligand ammonium-chloride-fluoride electrolyte and a mode of electrolysis for the deposition of functional coatings formed by tin-nickel alloys. The tin-nickel alloy with a tin content of 65 wt.% and a nickel content of 35 wt.% proves to be the most promising for microelectronics in the case of its application instead of gold coatings. It is shown that the obtained coatings are suitable for soldering with the use of low-temperature solders and acid-free fluxes and for the ultrasonic spot welding. The electrolytic deposits of tin-nickel alloys are investigated as the anodes of lithium-ion batteries by the potentiodynamic and galvanostatic cycling methods. It is shown that the deposits obtained from an alkaline tartrate-trilonate electrolyte are characterized in the first cycles by a high specific capacity of up to 700 mA ∙ h/g. In the course of cycling, this parameter decreases to 500 mA ∙ h/g. The obtained tin-nickel alloys guarantee high densities of charge-discharge currents without mechanical fracture. [ABSTRACT FROM AUTHOR]

In this work, Sn-Ni alloy coatings were developed onto the surface of copper from a newly formulated electrolytic bath by a simple and cost-effective electrodeposition technique using gelatin as an additive. The electrocatalytic behavior of coatings deposited at different current densities (c.d.'s) for water-splitting applications, in terms of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), has been researched. The experimental results showed that the electrocatalytic activity of Sn-Ni coatings has a close relationship with its composition, surface morphology, and phase structure depending on the c.d. used, supported by scanning electron microscopy (SEM-EDX) and X-ray diffraction (XRD) analyses. Cyclic voltammetry and chronopotentiometry techniques have demonstrated that Sn-Ni alloy deposited at 4.0 A dm (having 37.6 wt pct Ni) and 1.0 A dm (having 19.6 wt pct Ni) exhibit, respectively, the highest electrocatalytic behavior for HER and OER in 1.0-M KOH solution. Sn-Ni alloy coatings were found to be stable under working conditions of electrolysis, confirmed by electrochemical corrosion tests. High electrocatalytic activity of Sn-Ni alloy coatings for both HER and OER is specific to their composition, surface morphology, and active surface area. [ABSTRACT FROM AUTHOR]

The structural damage induced by huge volume change during lithiation/delithiation results in poor cycle stability of tin-based anode materials, which becomes the major obstacle to their practical application. In this work, we fabricated three-dimensional (3D) porous bowl-shaped carbon cages interspersed with carbon coated Ni–Sn alloy nanoparticles (Ni3Sn2 and Ni3Sn4; 10–30 nm) by a freeze-drying method with self-assembled NaCl as a template followed by annealing. Both Ni3Sn2/C and Ni3Sn4/C exhibit excellent electrochemical performance as anode materials for lithium-ion batteries. In particular, the Ni3Sn4/C nanocomposites exhibit superior rate capability (735, 661, 622, 577, 496, and 377 mA h g−1 at 0.1, 0.2, 0.5, 1, 2, and 5 A g−1, respectively) and excellent cycling stability (568 mA h g−1 at 0.5 A g−1 for the second cycle and gradually increased to 732 mA h g−1 after 200 cycles). The superior electrochemical performance is attributed to the synergetic effect of Ni–Sn alloy nanoparticles and 3D porous bowl-shaped carbon networks. The uniformly embedded Ni–Sn alloy nanoparticles can effectively alleviate the absolute stress/strain and shorten the Li+ diffusion path, and Ni in the Ni–Sn alloy acts as a buffer to suppress the volume expansion. Moreover, the 3D bowl-shaped carbon networks with high conductivity can provide abundant space for volume expansion, suppress the agglomeration of Ni–Sn nanoparticles, ensure the structural integrity, and facilitate lithium-ion diffusion as well as electron transportation. [ABSTRACT FROM AUTHOR]

The thermodynamic optimization of the Ni-Sn-Bi ternary system was performed using the Calphad method and experimental data obtained by Differential Scanning Calorimetry and Scanning Electron Microscopy. The ternary phase was described using a three-sublattice model. The previously reported new ternary compound and the solubility of the third element in two binary systems (Bi in Ni-Sn and Sn in Bi-Ni) were included in the optimization. Four isothermal sections were calculated using Thermi-Calc software and compared with the experimentally obtained ones. A miscibility gap in the ternary system was found at 1610 K. [ABSTRACT FROM AUTHOR]

The transformations of a Cu-10wt%Ni-5.5wt%Sn alloy as a function of the aging time in the range from room temperature up to 600 °C have been followed by Differential Scanning Calorimetry (DSC). The results obtained have shown that this alloy undergone two overlapping exothermic phase transitions with DSC peaks at 208 °C and 305 °C, respectively, followed by an endothermic phase transformation with a DSC peak at 526 °C. The structural analysis by TEM, ED, EDX and XRD of the intermediates phases previously discriminated by DSC suggests that the first exothermic peak is associated to the spinodal decomposition of the sample, while the second one is associated to the segregation of a DO 22 (Cu x Ni 1−x ) 3 Sn tetragonal phase coherent with the α-Cu structure of the starting alloy. The endothermic peak has been associated to the precipitation of cubic DO 3 nanocrystals from the DO 22 phase previously formed. The microhardness measurements carried out in combination with the structural characterization demonstrate that the aging hardening of the alloy under study is exclusively due to the formation of the coherent DO 22 phase. The DO 22 → DO 3 transition leads to a dramatic drop of the hardness of the alloy. [ABSTRACT FROM AUTHOR]

A new approach is developed to fabricate single-crystal Sn solder joints with a line-type structure. The primary purpose is to investigate the diffusion characteristics of Ni in single-crystal Sn with four different grain orientations during electromigration. An interesting new experimental phenomenon that Ni 3 Sn 4 forms on the surfaces of single-crystal Sn with regularity occurs which should be attributed to the extremely anisotropic diffusion property of Ni in single-crystal Sn. Besides, the diffusion velocity of Ni in single-crystal Sn during electromigration is ranked as followed: (001)> (101)> (301)> (100). Experimental observations are in good agreement with kinetic analysis. [ABSTRACT FROM AUTHOR]

During thermal stabilization, the (Ni 3 Sn 2 +liquid) and (Ni 3 Sn 4 +liquid) mushy zones were formed between the complete liquid zone and the non-molten zone due to the imposed temperature gradient. The morphology of the interface between these mushy zones changed during thermal stabilization. A thin liquid film which gradually disappeared was formed between the mushy zones at the initial of thermal stabilization. Due to the solute diffusion through the liquid channels by temperature gradient zone melting (TGZM), the triple junctions at T P gradually moved upwards, leading to serrated interface. If the thermal stabilization time is long enough, this interface is smoothed. [ABSTRACT FROM AUTHOR]

The time-consuming of transient-liquid-phase is a big challenge for the die bonding. In this paper, a novel rapid bonding method plus alloying design was proposed to cheaply fabricate Sn Ni intermetallic joint for high temperature electronic packaging. The ultrasonic effect and the evolution of the joint microstructures, shear strength as a function of Ni content were systemically investigated. The amount of Ni 3 Sn 4 in the joint increased with the addition of Ni, and when the Ni content reached 24 wt.%, the joint consisted of nearly sole Ni 3 Sn 4 with a high shear strength of 43.4 MPa was achieved. After aging at 300 °C for 72 h in air, the shear strength of the joint obtained with smaller Ni content solder showed great improvement because of the phase transformation of residual Sn to Ni 3 Sn 4 , but for the Sn-24 wt.%Ni and Sn-30 wt.%Ni, it showed a little decrease due to the grains coarsening of Ni 3 Sn 4 . The acoustic cavitation and streaming effects dramatically accelerates the reaction of Ni and Sn during the ultrasonic-assisted soldering. The joint obtained by the Sn-24 wt.%Ni solder has the best potential to be applied in the power electronic packaging. [ABSTRACT FROM AUTHOR]

Although long nanotubes with a large specific surface area are desirable in many applications, it is difficult to produce long Ni-Ti-O nanotubes on nearly equiatomic NiTi alloy in fluoride (F)-containing ethylene glycol (EG) by anodization. In this work, a new electrolyte composed of EG, H 2 O, and HCl is designed and adopted to fabricate long nanopores rather than nanotubes on the NiTi alloy. By applying an anodization voltage of 10 V to the EG solutions containing 5.0–11.0 vol% H 2 O and 0.125–0.75 M HCl, Ni-Ti-O nanopores with a diameter of about 70 nm are produced. The nanopore length increases almost linearly with anodization time and by optimizing the experimental conditions, nanopores with a length of 160 μm can be prepared. [ABSTRACT FROM AUTHOR]

The aim of this article is to analyze the elastocaloric effect of a commercial Ni-Ti plate for its application in a cooling device. In the first part, the article shows numerical results of the cooling characteristics of a regenerator-based elastocaloric cooling device with different thickness of the Ni-Ti plates based on a previously developed numerical model. It is shown that such a device (with a plate thickness of 0.1 mm) can produce a specific cooling power up to 7 kW/kg and coefficient of performance values up to 5 at the 30 K of the temperature span. In the second part of the article, a testing and analysis of the elastocaloric effect of the Ni-Ti plate using infrared thermography is shown. Prior to the elastocaloric testing, the sample was mechanically polished and subjected to 200 loading–unloading cycles at a slow strain-rate and 10,000 loading–unloading cycles at high strain-rate to stabilize its superelastic behavior and evaluate its fatigue life. When the functional and structural stability was reached and relatively good fatigue resistance was proven, the elastocaloric effect of the sample was studied with an infrared camera as a function of strain-rate and applied strain. It is shown that the adiabatic conditions are well approximated at strain-rates above 0.1 s−1. The largest adiabatic temperature change of 14 K during loading and 12.5 K during unloading were measured at the applied strain of 4.2% (at a strain-rate of 0.33 s−1). The homogeneity of the elastocaloric effect and the temperature irreversibilities during unloading are presented and discussed. It can be concluded that thin Ni-Ti plates with suitable austenitic finish temperature are good candidates to be applied in a proof-of-concept regenerator-based cooling device. [ABSTRACT FROM PUBLISHER]

The Ni–Sn alloy was synthesized using borohydride assisted chemical reduction method. The composition of the synthesized alloy was determined using atomic absorption spectroscopy which revealed that the observed composition of Sn is high when compared to the initial composition. The ultrafine particles are clearly observed from field emission scanning electron microscope for all the sample. The X-ray diffraction measurement confirmed that the as-synthesized samples are of amorphous like nature while the samples annealed at 773 K showed crystalline nature. The Fourier transform infrared spectroscopy confirmed metallic bond stretching in the alloy samples. The crystallization and phase transition temperature was observed from differential scanning calorimetry. The shift in the crystallization temperature of Ni with increasing percentage of Sn was observed. The vibrating sample magnetometer was employed to understand the magnetic behavior of the Ni–Sn alloy. As-synthesized alloy samples showed paramagnetic nature while the annealed ones exhibit the soft ferromagnetic, antiferromagnetic and paramagnetic nature. The saturation magnetization value and magnetic ordering in the Ni–Sn alloys depend on the percentage of Sn present in the alloy. [ABSTRACT FROM AUTHOR]

Microsegregation is influenced by many factors during solicitation while the coupling effects of some important factors have been dismissed. During directional solidification of Sn–36at.%Ni peritectic alloys under high temperature gradient, melting/solidification of both the primary and peritectic phase caused by temperature gradient zone melting has been observed. An analytical model has been proposed to analyze the effect of temperature gradient zone melting on microsegregation of interdendritic melt in peritectic alloys. The coupling influences of peritectic reaction, coarsening process and solid state back-diffusion have all been included in this model. Both the experimental and theoretical analyses have demonstrated that melting/solidification of both the primary and peritectic phase could be accelerated by temperature gradient zone melting during peritectic solidification. Thus, microsegregation of interdendritic melt is restricted by temperature gradient zone melting during peritectic solidification. The analytical model in the present work shows inherent consistence with our previous models. [ABSTRACT FROM AUTHOR]

The grain growth and thermal stability after recrystallization in as-solidified highly undercooled Ni-3at.%Sn alloy melt were investigated. As for undercooled Ni-3at.%Sn alloy, a transition from dendritic to granular crystals occurred when Δ T ≥Δ T * , which was induced by the plastic deformation of dendrites and subsequent recrystallization. On this basis, the subsequent grain growth and solute segregation accompanying recalescence were calculated by a recently proposed thermo-kinetic model, which showed close agreement with the experimental results. It is concluded that the grain growth process was interrelated to recalescence, solute trapping and solute segregation of Sn atoms captured by solute trapping, which was responsible for the reduction of grain boundary energy and improvement of thermal stability. [ABSTRACT FROM AUTHOR]

A systematic study on the phase transformation behavior in a polycrystalline Ni–Ti–Fe shape memory alloy is reported. The investigation was carried out through series of differential scanning calorimetry (DSC) tests on three different samples with distinctly different microstructures of the alloy processed through different thermo-mechanical routes. The applied procedures involved cold rolling and marforming (rolling in liquid nitrogen) followed by short annealing treatments to recover the cold worked microstructure. These treatments altered the microstructure in terms of grain size, misorientation (defects) and texture. Three different microstructures were generated through adopted deformation processes (i) lower degree of texture, (ii) textured and (iii) refined grains with texture. The influence of the microstructural parameters on the phase transformations in terms of transformation temperature (TT) and associated energy of absorption/release was investigated. Temperature of transformation (TT) between different samples was affected predominantly by the grain size difference while enthalpy of transformation (austenite ↔ martensite) was mainly due to differences in texture, stored energy and in-grain misorientation. Though the differences in TT and enthalpy were not very significant, these results form a guideline for microstructure tailoring of bulk scale manufacturing of these alloys. [ABSTRACT FROM AUTHOR]

The electronic structure and magnetic properties of Hg 2 CuTi-type Mn 2 NiSn have been studied by performing the first-principle calculations. It is found that the phase transformation from the cubic to the tetragonal structure reduces the total energy, indicating that the martensitic phase is more stable and the phase transition from austenite to martensite may happen at low temperature for Hg 2 CuTi-type Mn 2 NiSn. Concerning the magnetism of Hg 2 CuTi-type Mn 2 NiSn, both austenitic and martensitic phases are suggested to be ferrimagnets. Furthermore, martensitic transformation decreases the magnetic moment per formula unit compared with austenitic phase. The results are helpful to accelerate the use of Mn 2 NiSn alloys in the series for magnetic shape memory applications. [ABSTRACT FROM AUTHOR]

Ni-Sn alloys have been prepared by electrodeposition technique on nickel net substrates from pyrophosphoric acid solution system. The morphology, chemical compositions and catalytic properties for hydrogen evolution reaction (HER) of the Ni-Sn alloys are found to be sensitive to the electrodepositing potentials, while the crystalline phases of the electrodeposits are almost unchanged regardless of the potentials according to the X-ray diffraction (XRD) results. The Ni-Sn alloy deposited at −1.5 V exhibits the hydrogen overpotential of 161 mV when the polarization current density of 300 mA cm −2 at 25 °C, which is lower than that of 341 mV for the Raney-Ni electrode. In addition, the Ni-Sn alloy shows high durability in 30 wt% KOH solution for at least 3 months. The results imply that the deposited Ni-Sn alloys can be applied in practical as cathode in industrial water electrolyzer. [ABSTRACT FROM AUTHOR]

Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases NiSn and NiSn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging. [ABSTRACT FROM AUTHOR]