Ni3Sn4 Phase Research Articles

Effect of Ni interlayer on microstructure and mechanical properties of Sn-based alloy/steel bimetallic materials via liquid-solid compound casting

Tin-based alloys have been widely used as an excellent bearing material. However, preparing of Tin/steel bimetallic materials with sound metallurgical interfaces has proven challenging. Importantly, a large number of brittle intermetallic compounds inevitably form at the interface, affecting the material's bonding properties. In this study, an electroplated Ni layer was used for the first time as an intermediate layer in Tin/steel bimetallic composites. It solves the problems of steel surface oxidation and poor wettability. Additionally, the introduction of the electroplated Ni layer impedes the formation of brittle phases, thereby improving interfacial bond strength. The results show that the Tin/steel interface of the Ni interlayer consists mainly of a large number of Ni3Sn4 phases rather than the commonly known FeSn2 phase. A thin layer of residual Ni plating also exists between the steel and the diffusion layer. Furthermore, the properties of Ni3Sn4 and FeSn2 phases were calculated using first-principles calculations. A Tin/steel bimetallic interface achieved a maximum shear strength of 58.63 MPa in the presence of the Ni intermediate layer. At that time, the residual thickness of the Ni layer was 1.5 μm, and the thickness of the diffusion layer was 4.8 μm.

Investigation of bio-corrosion behavior, structural and thermal properties of Ni20Ti50Sn30 high-temperature shape memory alloy

In this study, Ni20Ti50Sn30 (atomic %) sample was prepared using the arc melting method. Some thermodynamic parameters (phase transformation temperatures, PTT; enthalpy, ΔH; and phase transformation hysteresis, H) obtained from the phase transformations of the alloy were determined using differential scanning calorimetry (DSC). The sample exhibited high-temperature shape memory alloy (HTSMA) properties. X-ray (XRD) analysis was performed to determine the crystal structure properties at the alloy. The presence of B2, B19′, Ti2Ni, β-Ti, Ni3Sn4, TiNiSn and Ti3Sn phases was identified through X-ray analysis of the alloy. Scanning electron microscopy (SEM) was used to examine the pre- and post-corrosion surface morphologies of the sample, with EDX analysis being performed to reveal chemical structure determinations (matrix phases, precipitates and weathering zones). The presence of dendritic arms was observed, while martensite plates were absent in all SEM images. Particularly in the SEM image taken after corrosion, it was noted that the TiO2 layer placed on the surface of the matrix rich in Ti elements altered the surface morphology of the alloy. The presence of Ti and O elements in the post-corrosion EDX analysis confirmed the existence of this layer. Biocompatibility studies of the alloy were conducted using potentiodynamic corrosion tests and electrochemical impedance spectroscopy (EIS) methods. It was determined that the NiTiSn sample was in the excellent stability class according to corrosion standards.

Exceptional load-bearing capability of Al FPCB/Cu FPCB lap joints using instantaneous laser-based large area facial soldering: Experimental and numerical investigations

This study introduces a novel method for integrating aluminum flexible printed circuit boards (FPCBs) and copper FPCBs into battery management systems (BMS) using and instantaneous large area facial laser source soldering. Achieving a robust bonding strength of 65 MPa involved applying 600 W of laser power for 2 s, enhancing atom diffusion and promoting intermetallic compound (IMC) growth. Finite Element Method (FEM) simulations revealed variations in heat transfer between Al and Cu, affecting IMC thickness at interfaces. Formation of the (Cu, Ni)3Sn4 phase within solder, and variations in laser output significantly influenced solder joint orientation and Al electrode nucleation. Excessive laser power (>800 W) caused critical damage, such as delamination at the Al-PI interface, altering fracture modes and bonding strength. Furthermore, with a detailed examination of the laser soldering phenomenon through both experimental and numerical investigations, this study provides a thorough understanding of the different soldering mechanisms in conventional reflow soldering compared to instantaneous uniform large-area heat source laser soldering. These insights provide new design and material considerations to replace the conventional wiring harness with Al/Cu FPCB lap joints which optimize the circuitry and reducing BMS volume.

Achieving outstanding mechanical property after long-cycle thermal shock of reflow/ultrasonic-assisted Kovar/SnSb10 interfaces

The present study analyzed the microstructure evolution corresponding to the mechanical properties of reflow/ultrasonic-assisted Kovar/SnSb10/Fe joints after long-cycle thermal shock (TS). The results indicate that the thickness of interfacial intermetallic compounds (IMCs) at Kovar/SnSb interface with ultrasonication was less than 1 μm even after 2000 cycles, and almost no defects were detected, exhibiting superior microstructure stability. The ultimate shear strength with and without ultrasonication reached 58 MPa and 45 MPa, respectively. From TEM analysis, the nanoprecipitates inside Sn or IMC region primarily consisted of Ni3Sn4 and Ni3Sn phases. The ultimate outstanding mechanical property after long-cycle TS was attributed to dispersed strengthening and dislocation strengthening. This work provides valuable insights into the stability and reliability of the Kovar/SnSb10 system.

Effect of Sn addition on microstructure, hardness and corrosion behavior of CoCrFeNiSnx high entropy alloys in chloride environment

The microstructure, hardness and corrosion behavior of CoCrFeNiSnx (x = 0, 0.1, 0.5 and 1.0) HEAs were investigated in this work. The increase of the Sn addition resulted in the improvement of hardness (reached 424.9 HV) which attributed to the increase of the Ni3Sn2 phase with higher hardness. Adding Sn with molar ratio of 0.1 promoted the pitting initiation due to the potential difference between the two phases. CoCrFeNiSn0.5 and CoCrFeNiSn1.0 exhibited enhanced corrosion resistance compared to the alloy without Sn, which ascribed to the increase in cathode area (Ni3Sn2 phase) leading to a decrease in pitting sensitivity of FCC phase.

Effect of Sn addition on the low temperature shrinkage of Ni nanoparticles

In this study, in-situ formation of intermetallic compound (IMC) was proposed to reduce the sintering shrinkage mismatch between Ni electrode and dielectric material for multilayer ceramic capacitors (MLCCs). Tin (Sn) was selected as an alloying element and introduced in the form of SnCl2 into Ni nanopowder. The Sn precursor was decomposed at ∼450 °C and a cubic Ni3Sn intermetallic phase was formed at 500 °C, which was gradually transformed to a hexagonal Ni3Sn phase at 700 °C and thereafter thermally decomposed above 800 °C forming the Ni–Sn solid solution. The Sn addition shifted the shrinkage onset temperature of Ni electrode to a higher temperature by 300–400 °C and effectively retarded the low temperature densification through in-situ formation of Ni3Sn intermetallics by inhibiting the inter-diffusion between Ni nanoparticles. Furthermore, the sintered Sn added Ni (Ni–3Sn) electrode exhibited an electrical conductivity comparable to that of pure Ni electrode, demonstrating its suitability as an alternative electrode for MLCCs.

Metallic Honeycomb Catalysts for Methane Steam Reforming: Effect of the Bimetallic Surface Coating on Catalytic Properties

Metallic honeycomb catalysts are promising candidates for fuel cell and small-scale onsite hydrogen production applications. In this study, high-cell-density Ni honeycomb catalysts coated with a series of bimetallic surface layers were synthesized. Their catalytic performance for CH4 steam reforming was investigated under a low steam-to-carbon ratio of 1.36 and a gas hourly space velocity of 6400 h-1 in the temperature range of 400–700°C. The catalysts coated with Ni-Mg and Ni-Zr showed excellent catalytic performance, reaching a high CH4 conversion and CO selectivity close to the equilibrium values within the test temperature range. The enhanced catalytic performance of the Ni-Mg and Ni-Zr coatings was attributed to the formation of oxide-supported fine Ni particles. In contrast, the catalysts coated with Ni-Fe and Ni-Sn exhibited an extremely low activity, which was lower than that of the catalyst coated with only Ni. The low activity of the Ni-Fe and Ni-Sn coatings is supposed to be due to the formation of aggregated Ni3Fe, Ni3Sn, and Ni3Sn2 phases.

Effect of Undercooling on the Microstructure and Mechanical Properties of Hyper-eutectic Ni–Sn Alloy

In this study, container-less solidification of hyper-eutectic Ni–Sn alloy has been performed by using the electromagnetic levitation technique. The effect of undercooling on the formed microstructure and on the mechanical properties have been investigated. Growth velocities were determined by high-speed video-imaging of the solidification process. A step change in the growth velocities that are increasing with increasing undercooling is observed. This aligns with an observed first change in the microstructure between low and intermediate undercoolings. At the lower undercoolings, a pro-eutectic Ni3Sn phase along with lamellar eutectic structure in the inter-dendritic region is found. At intermediate undercooling of 100–150 K, a divorced eutectic microstructure is observed whereas at undercoolings above 165 K α-Ni precipitates are observed within β-Ni3Sn dendrites. Microhardness testing revealed higher strength for the lamellar phase as compared to the non-lamellar phase. Nano-indentation has been performed to determine the hardness and strength of individual phases in the microstructure.

Effect of Nanosized Ni Reinforcements on the Structure of the Sn-3.0Ag-0.5Cu Alloy in Liquid and After-Reflow Solid States

The Sn-Ag-Cu (SAC) alloy family is commonly used in lead-free solders employed in the electronics industry, for instance, SAC305, SAC387, SAC405, etc. However, the trend in manufacturing small electronic products and device miniaturization faces some disadvantages in terms of mechanical properties and their higher melting temperatures compared to Pb-Sn solders, prompting new research relating to the reinforcement of existing SAC solders. The current study presents structural features of nanocomposite (Sn-3.0Ag-0.5Cu)100−x(nanoNi)x solders with 0.5 wt.%, 1.0 wt.%, and 2.0 wt.% Ni. Structural analysis of the investigated samples were performed by means of X-ray diffraction in a liquid state and scanning electron microscopy (SEM). SEM showed the mutual substitution of Ni and Cu atoms in the Cu6Sn5 and Ni3Sn4 phases, respectively. The performed structural studies in liquid and solid states provided essential information concerning the structural transformations of liquid Sn-3.0Ag-0.5Cu alloys caused by minor additions of nanosized Ni powder. The melting point and degree of undercooling of the samples were investigated by DTA analysis.

Synergistic effects of alloy elements on the structural stability, mechanical properties and electronic structure of Ni3Sn4: Using first principles

Ni3Sn4 and Ni3Sn4-based ternary phases play an important role in the interfacial connection in solder joints. In this study, we provide a detailed investigation of the structural stability, mechanical properties and electronic structures of Ni3-xMxSn4 (M = Co, Pd, Pt and Cu，x = 0–1.5) and Ni3Sn4-xNx (NIn, Ge, Pb and Sb，x = 0–1.5) using first-principles methods. The calculated formation enthalpies reveal that the alloy elements (Pd, Pt, Ge and Sb) can improve the structural stability of Ni3Sn4, but Co, Cu, In and Pb do the opposite. The elastic constants (Cij) of Ni3-xMxSn4 and Ni3Sn4-xNx structures are typically lower than those of Ni3Sn4. Cu and Sb elements are detrimental to the ductility of Ni3Sn4, and the elements of Ge and Pb can improve the ductility of Ni3Sn4. The rest of elements (In, Co, Pd and Pt) have less influence on the ductility and brittleness of Ni3Sn4. Electronic structure analysis shows that the trend of the Fermi Level values (Ef) are consistent with the formation enthalpies (Hf) of Ni3-xMxSn4 and Ni3Sn4-xNx. The orbitals hybridization between Ni-d, M-d, Sn-p and N-p have a significant effect on Ni3Sn4. Finally, the bulk modulus (B), shear modulus (G), Young's modulus (E), Poisson's ratio (ν), and differential charge density are calculated completely.

Mechanistic Insights into the Formation of Thermoelectric TiNiSn from In Situ Neutron Powder Diffraction.

Half-Heusler alloys are leading contenders for application in thermoelectric generators. However, reproducible synthesis of these materials remains challenging. Here, we have used in situ neutron powder diffraction to monitor the synthesis of TiNiSn from elemental powders, including the impact of intentional excess Ni. This reveals a complex sequence of reactions with an important role for molten phases. The first reaction occurs upon melting of Sn (232 °C), when Ni3Sn4, Ni3Sn2, and Ni3Sn phases form upon heating. Ti remains inert with formation of Ti2Ni and small amounts of half-Heusler TiNi1+ySn only occurring near 600 °C, followed by the emergence of TiNi and full-Heusler TiNi2y'Sn phases. Heusler phase formation is greatly accelerated by a second melting event near 750-800 °C. During annealing at 900 °C, full-Heusler TiNi2y'Sn reacts with TiNi and molten Ti2Sn3 and Sn to form half-Heusler TiNi1+ySn on a timescale of 3-5 h. Increasing the nominal Ni excess leads to increased concentrations of Ni interstitials in the half-Heusler phase and an increased fraction of full-Heusler. The final amount of interstitial Ni is controlled by defect chemistry thermodynamics. In contrast to melt processing, no crystalline Ti-Sn binaries are observed, confirming that the powder route proceeds via a different pathway. This work provides important new fundamental insights in the complex formation mechanism of TiNiSn that can be used for future targeted synthetic design. Analysis of the impact of interstitial Ni on the thermoelectric transport data is also presented.

Understanding the non-monotonic variation in the corrosion rate of Sn-Ni coatings with Ni addition by the analysis of texture and grain boundary constitution of the matrix phase and spatial distribution of the intermetallic phase in the coating microstructure.

Sn-Ni coatings (0–13 wt% Ni) were electrodeposited on mild steel. The highest (Rp = 18,561.1 Ω·cm2) and the lowest (Rp = 4756.7 Ω·cm2) corrosion resistance was observed for Sn-6 wt% Ni and Sn-13 wt% Ni coating, respectively. Higher corrosion resistance of Sn-6 wt% Ni coating was due to low energy (100) surface texture, low energy CSL boundaries and formation of Ni3Sn4 phase at grain boundaries. Higher corrosion rate of Sn-13 wt% Ni coating was due to highest fraction of high energy high angle grain boundaries, higher matrix strain and higher volume fraction of cathodic Ni3Sn4 phase.

Effect of Ag and Cu co-addition on the microstructure evolution, interface behavior and mechanical properties of Sn-5Sb based solder joints subjected to different thermal aging conditions

In this work, the effect of Ag and Cu co-addition on the microstructure evolution, interface behavior and mechanical properties of Sn-5Sb based solder joints subjected to different thermal aging conditions were studied. It was found that in the joint of Sn-5Sb/ENIG, the solder matrix consisted of Ni3Sn4 phase, and the interface reaction product was Ni3Sn4 phase. In the joint of Sn-5Sb-0.7Ag-0.5Cu/ENIG, the Ag3Sn and (Ni, Cu)3Sn4 phases were observed in the solder matrix, and the interface was (Ni, Cu)3Sn4 phase. The co-addition of Ag and Cu reduced intermetallic compound (IMC) growth rate (0.85 × 10−14 cm2/s for Sn-5Sb, 0.37 × 10−14 cm2/s for Sn-5Sb-0.7Ag-0.5Cu at 175 °C), and improved the shear properties of the solder joints.

Study of Wettability and Solderability of SiC Ceramics with Ni by Use of Sn-Sb-Ti Solder by Heating with Electron Beam in Vacuum.

The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 °C. The solder consists of a tin matrix where the Ti6(Sb,Sn)5 and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33° was obtained in a vacuum at the temperature of 950 °C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi2 and Ti3Ni5Si6 phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni3Sn2 and Ni3Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 °C.

Investigation of phase equilibria of the Au–Ni–Sn ternary system and interfacial reactions in the Au/Sn/Ni/Cu multilayer couple

Au and Ni are widely used in the under-bump metallization, whereas Sn and Cu serve as common bonding materials and substrates, respectively. Solder joints consisting of an Au/Sn/Ni/Cu multilayer structure are widely found in the electronic packaging. Both phase equilibria of the Au–Ni–Sn ternary alloys and interfacial reactions of the Au/Sn/Ni/Cu multilayer structure were applied to the solid/solid-state reaction couple technique. The results showed that the Ni3Sn2 and AuSn4 phases respectively had a great solubility of the third element and the ternary AuNi2Sn4 phase existing in the Au–Ni–Sn ternary alloys was formed at 180 and 240 °C. The Sn/Ni/Cu multilayer structure was prepared by electroplating Sn/Ni layers on the Cu substrate. Afterward, the Sn/Ni/Cu multilayer and Au foil were screwed together to obtain the Au/Sn/Ni/Cu multilayer structure, followed by reactions at 150, 180 and 200 °C for different durations. The thickness of the intermetallic compounds (IMCs) increased with the increase in the reaction time and temperature. The IMC evolution in the couple remained unchanged at different temperatures. An increase in the reaction time converted the AuSn4 and AuSn2 phases to the AuSn phase. The voids formed in the couple were attributed to the volume shrinkage effect, which decreased with an increase in the reaction temperature. The (Ni, Au)3Sn2 phase was formed at the Ni side; the Ni layer functioned as an effective diffusion barrier to prevent the formation of the Cu–Sn IMCs.

Effect of Sn addition on the tribological behaviors of CoCrFeNi high entropy alloys

The present work investigated the effect of Sn on the microstructure, hardness, and tribological behaviors of CoCrFeNi high entropy alloys fabricated via vacuum arc melting. The results showed that Sn addition in CoCrFeNi alloys led to a distinct structure change from single FCC to dendritic microstructure in which Ni3Sn2 phase was distributed between the FCC dendrites. With the increase in Sn content, the volume fraction of Ni3Sn2 phase increased and thus brought about the improved hardness due to the second phase strengthening. The friction and wear test indicated that the best tribological performance was achieved by Sn1 alloy under a load of 2 N (the friction coefficient and wear rate were as low as 0.21 and 2.7 × 10−5 mm3/N∙m, respectively), which was attributed to the competitive effect between the applied load and Sn content. Moreover, the wear mechanisms of CoCrFeNiSnx alloys during sliding were carefully discussed.

Influence of hexagonal to orthorhombic phase transformation on diffusion-controlled dendrite evolution in directionally solidified Sn–Ni peritectic alloy

The hexagonal to orthorhombic (HO) transformation from β-Ni3Sn2 (hexagonal) phase to α’-Ni3Sn2 (orthorhombic) phase was confirmed in directionally solidified Sn–Ni peritectic alloys. It is shown that the remelting/resolidification process which is caused by both the temperature gradient zone melting (TGZM) and Gibbs−Thomson (G−T) effects can take place on secondary dendrites. Besides, the intersection angle between the primary dendrite stem and secondary branch (θ) is found to increase from π/3 to π/2 as the solidification proceeds. This is the morphological feature of the HO transformation, which can change the diffusion distance of the remelting/ resolidification process. Thus, a diffusion-based analytical model is established to describe this process through the specific surface area (SV) of dendrites. The theoretical prediction demonstrates that the remelting/resolidification process is restricted when the HO transformation occurs during peritectic solidification. In addition, the slope of the prediction curves is changed, indicating the variation of the local remelting/resolidification rates.

Electrodeposition of Ni–Sn alloy from ethylene glycol electrolyte. Part 1. Cathodic reactions

ABSTRACT A new ethylene glycol electrolyte for nickel-tin coatings electrodeposition based on Ni(II) and Sn(II) chlorides and citric acid has been developed. It ensures the formation of coatings with high (about 40 wt%) nickel content, which include Ni3Sn2 and Ni3Sn4 phases. The electrolyte is stable during operation and storage, and provides growth of coatings at a rate of 9–18 μm h–1 and current efficiency of 89–94%. Citric acid stabilises the electrolyte by inhibiting the oxidation of Sn(II) during storage; in addition, it increases current efficiency, slowing down the reduction of hydrogen. According to voltammetry data the joint reduction of Sn(II) and Ni(II) from citrate-glycol electrolyte occurs with the effect of depolarisation due to the formation of intermetallics.

Analysis on phase nucleation in Sn-Ni peritectic alloy combining confocal laser scanning in-situ observation and differential scanning calorimetry

The analysis of the phase nucleation requires not only the in-situ images but also the accurate nucleation information. Thus, the nucleation of both the primary Ni3Sn2 and peritectic Ni3Sn4 phases were studied during peritectic solidification of Sn-Ni alloy using the high temperature confocal laser scanning microscope (HT-CLSM) and differential scanning calorimetry (DSC). The results by both methods confirm that the nucleation undercooling ∆T of the solid phases decrease with increasing cooling rates, which is demonstrated to be caused by higher concentration difference at larger cooling rates. Besides, the freezing range of the alloy is also found to decrease with the increase in cooling rate. However, the nucleation undercooling of the peritectic Ni3Sn4 phase determined by HT-CLSM is larger than that by DSC at each cooling rate. This is attributed to the slower capture of peritectic reaction when using HT-CLSM. Furthermore, the nucleation of peritectic Ni3Sn4 phase is confirmed to be controlled by the heterogeneous nucleation on primary Ni3Sn2 phase by comparison between the HT-CLSM observation and DSC result. In addition, the wetting angles for heterogeneous nucleation of both phases which are important parameters in analyzing the nucleation of solid phases were determined through the entropy of solidification data from the DSC results. The smaller wetting angle of peritectic Ni3Sn4 phase as compared with that of the primary Ni3Sn2 phase further proving the smaller nucleation undercooling of Ni3Sn4 phase during solidification.

Effects of doping trace Ni element on interfacial behavior of Sn/Ni (polycrystal/single-crystal) joints

PurposeThe purpose of this article is the effect of doping minor Ni on the microstructure evolution of a Sn-xNi (x = 0, 0.05 and 0.1 wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment. Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of interfacial layer was different due to the different mechanism of element diffusion of the two substrates. The PC Ni substrate mainly provided Ni atoms through grain boundary diffusion. The Ni3Sn4 phase of the Sn0.05Ni/PC Ni joint was finer, and the diffusion flux of Sn and Ni elements increased, so the Ni3Sn4 layer of this joint was the thickest. The SC Ni substrate mainly provided Ni atoms through the lattice diffusion. The Sn0.1Ni/SC Ni joint increases the number of Ni atoms at the interface due to the doping of 0.1Ni (wt.%) elements, so the joint had the thickest NiSn4 layer.Design/methodology/approachThe effects of doping minor Ni on the microstructure evolution of an Sn-xNi (x = 0, 0.05 and 0.1 Wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment was investigated in this study.FindingsResults showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of the interfacial layer was different due to the different mechanisms of element diffusion of the two substrates.Originality/valueIn this study, the effect of doping Ni on the growth and formation mechanism of IMCs of the Sn-xNi/Ni (single-crystal) solder joints (x = 0, 0.05 and 0.1 Wt.%) was investigated.