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:In this study, Ag3Sn nanoparticles were synthesized using the redox method and incorporated into SAC305 solder at varymg mass ratios (0, 0. 1 %,0.15%,0.2%)to investigate their impact on the microstructure, wettabihty, and rehabihty of the solder. The physical phase and morphology of the Ag3Sn nanoparticles were characterized by X-ray diffractometer and scanning e!ectron microscope, whUe the microstructure of the solder jonis was observed using a metallograplic microscope. Subsequently, the solder jonis were aged at 150 C for different durations(0, 50, 100, 150, 200 h), and the interfacaal intermetalic compound (IMC) layer thickness was measured usng Image J software to caiculate the growth coefticienr. Resuits indicate that the addition of an appropriate amount ofAg3Sn nanoparticles to SAC305 solder enhances wettabiiity, refines the microstructure, and inhibits IMC layer growth. As aging progresses, the Cu6Sn5 nntermetanic compound layer transitions from scalloped to pknar, accompaned by the appearance of the Cu3Sn nntermetanic compound aye. The optimal performance was observed with the addition of 0. 15 w. % Ag3Sn nanopartides to SAC305 solder, r esulting n improved wettabiity(spreading area of 167. 447 mm2), minimal growth coefficient(0. 04), and enhanced microstructural refinement [ABSTRACT FROM AUTHOR]

This study reports magnetic graphene oxide composite microspheres (MGO) were firstly synthesized via one step miniemulsion polymerization. α-FeOOH rods were then loaded onto MGO via a facile hydrothermal method to prepare α-FeOOH@MGO, which was served as the photocatalyst for the Fenton reaction. Subsequently, the properties of the resulting α-FeOOH@MGO were characterized by FT-IR, XRD, SEM, VSM and UV-vis DRS analysis methods. The influence of various parameters was investigated, such as dye type, dye concentration, H2O2 dosage, catalysts dosage and pH of MO solution during heterogeneous photo-Fenton processes. Under visible light irradiation, the degradation rate of MO, MB and CR could reach 99.96%, 98.47% and 99.97% in 40 min, respectively. Six cycle experiments confirmed that the α-FeOOH@MGO possessed a satisfied stability and recycling ability. In addition, the photocatalytic reaction mechanism was also revealed by the Mott-Schottky plot, band structure and trapping experiments of active species. [ABSTRACT FROM AUTHOR]

The influence of doping with Ge on the nonlinear coefficient α and the breakdown electric field E B of TiO 2 –Ta 2 O 5 –CaCO 3 varistor ceramics was investigated. In this study, TiO 2 –Ta 2 O 5 –CaCO 3 varistor ceramics added with Ge was successfully prepared using the traditional method of ball milling–molding–sintering. The electrical performance, including the nonlinear coefficient α , the breakdown electric field E B , and the leakage current J L , are tested using a varistor direct current parameter instrument. The average barrier height Φ B of each sample is calculated using the relevant formula. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and scanning transmission electronic microscopy analyses demonstrated that Ge doping notably changed the microstructure of TiO 2 –Ta 2 O 5 –CaCO 3 ceramics, thereby increasing α and decreasing E B . When the doping contents of Ta 2 O 5 and CaCO 3 were 0.2 and 0.4 mol%, respectively, the optimum doping content of 0.9 mol% Ge exhibited high α (10.2), low E B (14.1 V mm −1 ), and high Φ B (0.95 eV). These results are superior to previous findings. In addition, Ge as sintering aid reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1300 °C for the TiO 2 –Ta 2 O 5 –CaCO 3 ceramics doped with Ge. [ABSTRACT FROM AUTHOR]

This study investigated the influence of codoping with Ge and GeO2 on the nonlinear coefficient α and the breakdown voltage EB of TiO2-Nb2O5-SrCO3 varistor ceramics. Ge-GeO2 codoping notably changed the microstructure of the TiO2-Nb2O5-SrCO3 ceramics, increased α, and decreased EB. When the doping contents of Nb2O5 and SrCO3 were 0.1 and 0.2 mol%, respectively, the optimum doping content of 0.25 mol% Ge and 0.75 mol% GeO2 exhibited high α (11.6), low EB (13.8 V/mm), and high grain-boundary barrier ΦB (0.96 eV). These results are superior to previous findings. In addition, Ge and GeO2, which function as sintering aids, reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1260°C for the TiO2-Nb2O5-Sr CO3 ceramics doped with Ge and GeO2. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of co-doping with elemental crystal Ge or/and GeO 2 on the TiO 2 –Ta 2 O 5 –BaCO 3 varistor ceramic. Results showed that with the doping content of Ta 2 O 5 and BaCO 3 of 0.3 mol% and 0.2 mol%, respectively, the optimum doping content of 0.4 mol% Ge and 1.2 mol% GeO 2 exhibited the highest α value ( α = 12.1), lower breakdown voltage E B ( E B = 20.8 V mm − 1 ), lesser leakage current J L ( J L = 11.5 μA cm − 2 ), and highest grain boundary barrier Φ B ( Φ B = 0.93 eV). The microstructural analyses indicated that Ge–GeO 2 co-doping notably changed the TiO 2 –Ta 2 O 5 –BaCO 3 ceramic microstructure, increased α , and decreased E B . In addition, Ge and GeO 2 , which function as sintering aids, reduced the sintering temperature caused by the low melting point; the best sintering temperature was 1280 °C for TiO 2 –Ta 2 O 5 –BaCO 3 –Ge–GeO 2 ceramic. [ABSTRACT FROM AUTHOR]

Biochar was modified by an acylation reaction using EDTA. Then, a novel biochar-based porous composite was successfully prepared using modified biochar as a base to remove Cu(II) in wastewater. In addition, functional groups, morphologies and the specific surface areas of EDTA-BIOC hydrogel were characterized by FT-IR, SEM, and BET, respectively. Various factors affecting the adsorption of Cu(II) on EDTA-BIOC hydrogel were investigated, such as pH, temperature, contact time, salinity, and initial concentration of Cu(II). Addition of EDTA greatly improved the adsorption capacity for Cu(II), and the maximum adsorption capacity of EDTA-BIOC hydrogel for Cu(II) was 93.9 mg g−1 at 318 K, which was higher than for biochar, gel-0 and EDTA-BIOC/SiO2 hydrogel. Cu(II) adsorption on EDTA-BIOC hydrogel was shown to fit well with the pseudo-second-order kinetic model and Langmuir isotherm. The adsorption mechanisms of Cu(II) by the hydrogel are systematically discussed, including physical adsorption, electrostatic attraction, cation exchange and complexation. Furthermore, EDTA-BIOC hydrogel could maintain a high adsorption capacity after five adsorption–desorption processes, which provided the possibility for recycling the EDTA-BIOC hydrogel multiple times. Finally, the adsorption capacity of EDTA-BIOC hydrogel for Cu(II) was studied in various water samples. The experimental results showed that EDTA-BIOC hydrogel exhibited great potential for treating different wastewaters containing Cu(II). [ABSTRACT FROM AUTHOR]

The majority of studies on high-reliability solder alloys have focused on the six-element system of Sn, Ag, Cu, Bi, Sb, and Ni. However, there is limited research on the influence of Co element within this system. In this study, a Sn 3.0Ag 0.5Cu Bi Sb Ni xCo (x = 0 wt%, 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%) alloy (referred to as SACBSN-xCo alloy) was prepared using a melting method. The mechanical properties of SACBSN-xCo alloy solder joints were evaluated through ultimate shear strength testing. The composition analysis of the alloy, phase composition examination, intermetallic compound (IMC) investigation and interfacial layer morphology analysis were conducted using ICP, XRD, SEM and EDS techniques respectively. Furthermore, the evolution process of solder structure and solder joint interface layer under different aging times was observed in detail. Results indicate that with the addition of Co element in the alloy solder system two heat release peaks appear during the solidification process; specifically when adding 0.05 wt% Co element content to the mixture it reduces supercooling degree by 15.17 °C to only 1.03 °C; Moreover wettability improvement can be achieved to some extent when adding either 0.02 wt% or 0.05 wt% Co content. The addition of trace Co can inhibit the excessive growth of IMC in the solder alloy matrix and refine the alloy structure. It can promote the growth of Cu 6 Sn 5 -based IMCs and inhibit the growth of Cu 3 Sn layer in intermetallic compound layer (IMCs). In addition, the mechanical properties and thermal fatigue stability of the solder joints are steadily improved by Co element. After adding Co element, the shear strength of the alloy solder joint is increased by about 14.84 %. After aging at 150 °C for 25 days, the shear strength of SACBSN-xCo alloy solder joints is increased by about 20.4 %, which significantly improves the thermal fatigue stability of the solder joints after high temperature aging treatment. The results show that when Co content is 0.05 wt%, the alloy solder has better comprehensive properties. • The addition of Co element can increase the nucleation point in the solder matrix, refine the structure, reduce the formation of large size intermetallic compounds and inhibit their overgrowth during high temperature treatment. • The addition of Co element can increase the nucleation density of IMC, and promote the growth of Cu6Sn5-based IMCs. Thicker Cu6Sn5-based IMCs act as a good diffusion barrier, preventing the mutual diffusion of Sn and Cu atoms. Thus impeding the growth of the Cu3Sn layer. • The addition of Co can effectively improve the shear resistance of the solder joint, and make the shear resistance of the solder joint show excellent stability in the process of high temperature aging treatment. [ABSTRACT FROM AUTHOR]

AlCoCrFeNiCuSn X (X = 0,0.03,0.05,0.1,0.2) high-entropy alloy coatings were prepared on the surface of 35CrMo steel by plasma cladding technology. The phase structure, chemical composition, microstructure and wear resistance of the coatings were studied by X-Ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), microhardness test and wear test. The results show that each coating structure is mainly dendrites. And the dendrites region (DR) consists mainly of Fe-based solid solution with BCC structure, while the interdendritic (ID) consists mainly of Cu-rich phase with FCC structure, and a small amount of AlN precipitated phase with HCP structure. The microhardness of the coating increases with the increase of Sn content. The wear resistance of the coating shows a non-linear trend of increasing and then decreasing with the increase of Sn content, and the Sn 0.1 coating has the best wear resistance. • The AlCoCrFeNiCuSn X high-entropy alloy coatings were prepared by plasma cladding. • The coatings consist of dendrites, mainly including BCC and FCC phase. • The BCC is Fe based solid solution, The FCC is Cu-rich phase. • The microhardness of coatings increases with the increase of Sn content. • Appropriate Sn content can improve the wear resistance of the coatings. [ABSTRACT FROM AUTHOR]

Recently, Pickering emulsions stabilized by photocatalytic nanomaterials have become a hotspot in the field of catalysis due to their high interfacial activity. However, since most photocatalytic nanomaterials are extremely hydrophilic, using them as stabilizers is unconvenient for Pickering emulsions construction. Herein, a novel magnetic Janus nanosheets (JMPSN/α-FeOOH) with Janus SiO 2 nanosheets as the carrier and iron oxyhydroxide (α-FeOOH) as the catalyst species, respectively, was successfully fabricated through a simple synthetic strategy, which could act as an environmental-friendly Pickering emulsion emulsifier and catalyst simultaneously. We demonstrated that JMPSN/α-FeOOH exhibited good emulsifying properties of various oil phases. Morever, JMPSN/α-FeOOH in the formed Pickering emulsion-based photocatalytic system displayed significantly enhanced photocatalytic efficiency in degradation of dyes as compared to traditional non-emulsified systems while maintaining the stability of Pickering emulsion under constant irradiation. JMPSN/α-FeOOH could also quickly respond to external magnetic fields so as to achieve rapid recovery of catalyst, and catalyst still showed high catalytic activity after many catalytic cycles. Finally, a convenient and promising synthesis strategy for preparing Janus catalyst with low toxicity was proposed, which provided a guidance on how to effectively use the emulsion system stabilized by Janus catalyst to improve the degradation efficiency of various pollutants. [Display omitted] • An oil-in-water Pickering emulsion was stabilized by JMPSN/α-FeOOH without the use of any surfactants. • Pickering emulsion showed excellent photoefficiency and stability for dyes degradation. • JMPSN/α-FeOOH could quickly respond to external magnetic signals. • JMPSN/α-FeOOH still showed high catalytic activity after many catalytic cycles. [ABSTRACT FROM AUTHOR]

In order to improve the surface performance of Al-Zn-Mg-Mn-Zr extruded alloy, alumina coatings were directly prepared on the alloy in silicate electrolytes by direct current micro-arc oxidation technique. The relationship between discharge stages and technology parameters was studied, and then the growth behaviors, structure, composition and properties of coatings were further analyzed. Our work suggests that appropriately prolonging of the oxidation time at a low current density of 2 A/dm 2 can help to extend the action time of the micro-arc stage (Stage III) and to form a thicker layer with fewer inner defects. The compact inner structure promotes the hardness, elastic modulus as well as the corrosion resistance of the coatings. In contrast, the higher the current density, the earlier the discharge enters into the big arc stage (Stage IV), which has an adverse impact on the structure and properties of the coatings. In the Stage IV, the porosity of the coatings increases with the generation of mullite within the coatings comprise of γ-Al 2 O 3 and α-Al 2 O 3 . The growing direction of coatings changes from outward mainly to inward in the late stage of the micro-arc oxidation (MAO) process. [ABSTRACT FROM AUTHOR]

Based on the alloy Sn1.0Ag0.5Cu, Sb powder is added at a certain mass percentage to form the solder alloy Sn1.0Ag0.5CuxSb (x = 0 wt%, 0.5 wt%, 1.5 wt%). The melting point of the solder was determined by differential scanning calorimetry, the alloy interface morphology was observed by scanning electron microscopy, and energy-dispersive X-ray spectroscopy was performed to analyze phase compositions. Thermo-Calc software was used to calculate the variation in phase content, the solidification curve, Gibbs energy, the driving force, liquid/solid phase lines, the phase diagram, and the nucleation radius of Sn1.0Ag0.5CuxSb(wt%). In addition, the calculation results were used to explain the interface growth mechanism. According to the results, the precipitation/transition temperature of each phase and the content of the newly formed phase SnSb gradually increased with the increase in Sb content. After the addition of Sb, both temperatures of the liquid-phase line and the solid-phase line slightly increased, and the calculated values showed the same trend as the measured values. Two heat absorption peaks were observed during the melting process. The Gibbs energy and nucleation radius of the Cu 6 Sn 5 phase increased with the increase in Sb content, indicating that Sb can inhibit the growth of the Cu 6 Sn 5 phase. The addition of Sb rendered the Sn-rich phase denser and finer and reduced the thickness of the intermetallic compound layer and the generation of cracks; these changes intensified with increasing aging time. Comprehensive analysis revealed optimal reliability of the solder for an Sb content of 0.5 wt%. • With the increase of Sb content, the precipitation/transition temperature of each phase gradually increased, and the new phase SnSb phase gradually increased. • The Gibbs energy and nucleation radius of Cu 6 Sn 5 phase increased with the increase of Sb content. • Sb can obviously reduce the thickness of IMC layer and the crack generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel co-decorated magnetic graphene oxide composite adsorbent was constructed. • The q m for MB, MG, and CV were respectively 1372.32, 822.39, and 570.79 mg/g. • The good adsorption ability was ascribed to abundant active sites of PDA/MGO/CA-CD. • PDA/MGO/CA-CD presented good removal efficiencies in real water environment. In this work, a novel polydopamine and β-CD polymer co-decorated magnetic graphene oxide composite adsorbent (PDA/MGO/CA-CD) was facilely constructed, and systematically characterized by various characterization techniques. Subsequently, it was applied as a versatile adsorbent for purification of cationic dyes Methylene blue, Malachite green, and Crystal violet in wastewater. Under optimal conditions, the maximum adsorption capacities of PDA/MGO/CA-CD towards MB, MG, and CV were 1372.32, 822.39, and 570.79 mg/g, respectively. The adsorption kinetics investigate demonstrated that the adsorption experimental data fitted well with the pseudo-second-order kinetic model. Simultaneously, the adsorption isotherms data indicated good correlation coefficient and low error function for the Langmuir isotherm model. The thermodynamic consequences showed that the adsorption of cationic dyes on PDA/MGO/CA-CD was a spontaneous and endothermic process. Interestingly, the PDA/MGO/CA-CD can selectively capture cationic dyes from mixed cationic/anionic dye solutions. As-fabricated adsorbent possesses abundant functional groups which could adsorption cationic dyes via electrostatic interaction, hydrogen bonding, Yoshida H-bonding, π-π conjugation interaction, n-π interaction, and "host-guest" interaction. It was eventually revealed that the as-prepared PDA/MGO/CA-CD adsorbent was easy to be separated after adsorption and exhibited good reusability. More importantly, application on real water samples confirmed the high performance and potential of as-fabricated adsorbent for real cationic dyes remediation of environmental. [ABSTRACT FROM AUTHOR]

In this study, the interfacial structure and abnormal long-term increase of tensile strength in the interfacial intermetallic compounds (IMCs) between SnAg3Cu0.5 solder and Cu substrates during isothermal aging were investigated. After reflow soldering, the IMC layer at the interface was thin and scallop-type. The interfacial layer became thicker with the increase in aging time. After 200 h of aging at 150 °C, the thickness of the interface gradually increased to 3.93 μm and the interface became smooth. Compared with the unaged Cu-Sn interface, the aged joint interface contained more Cu3Sn. The top of the IMC being reflown was relatively smooth, but became denser and prismatic in shape after 200 h of aging at 150 °C. The tensile strength of the joint, immediately after the reflow, reached 81.93 MPa. The tensile properties of the solder joints weakened and then strengthened as they aged. After 200 h of aging at 150 °C, the tensile strength was 83.86 MPa, which exceeded that of the unaged solder joint interface, because the fracture mode of the solder joints changed during aging. [ABSTRACT FROM AUTHOR]

Ag-containing solder alloys are widely used in high-end electronic soldering processes to improve the reliability of electronic components. This study investigates the precipitation process of Ag 3 Sn during solidification. The precipitation of β-Sn, Ag 3 Sn, and η′-Cu 6 Sn 5 in SnAg3Cu0.5/Cu solder joints during solidification was examined using Thermo-Calc (2020a). Furthermore, the crystallographic structure of Ag 3 Sn/β-Sn and Ag 3 Sn/η′-Cu 6 Sn 5 was analyzed by transmission electron microscopy. The results showed that, below 217.1 °C, the η-Cu 6 Sn 5 phase begins to precipitate: β-Sn + Ag 3 Sn+η-Cu 6 Sn 5. At the Ag 3 Sn / β-Sn interface, the angle between (1 ‾ 2 1 ‾) A g 3 S n and (10 1 ‾) β − S n planes was measured to be 176.4°, with a mismatch of 26.47 %. The Ag 3 Sn / Cu 6 Sn 5 interface exhibited a specific crystallographic relationship of [ 223 ] A g 3 S n // [ 1 ‾ 12 ] C u 6 S n 5 , with an angle between (21 2 ‾) A g 3 S n and [ 402 ] C u 6 S n 5 planes of 101.5°. The growth patterns of β-Sn, Ag 3 Sn, and Cu 6 Sn 5 phases during isothermal aging were further investigated according to their interface orientation relationship, providing a basis for improving the stability of the soldering process. • Precipitation of β-Sn occurred when the temperature is cooled below 220.0 °C. Ag 3 Sn and η′-Cu 6 Sn 5 were distributed in blocks, with η′-Cu 6 Sn 5 possessing a large size. • The Ag 3 Sn / β-Sn exhibited [ 141 ] β − S n // [ 012 ] A g 3 S n relationship and 176.4° angle between (1 ‾ 2 1 ‾) A g 3 S n and (10 1 ‾) β − S n . • The Ag 3 Sn / Cu 6 Sn 5 exhibited [ 223 ] A g 3 S n // [ 1 ‾ 12 ] C u 6 S n 5 relationship and 36.1° angle between (21 2 ‾) A g 3 S n and (402) C u 6 S n 5 . [ABSTRACT FROM AUTHOR]

The phase structure and composition of the Cu/Cu 3 Sn interface were investigated during aging at 150 °C via transmission electron microscopy. The newly formed Cu 3 Sn phase was hexagonal, and the Cu substrate was cubic. However, the fine Cu grains that formed at the Cu/Cu 3 Sn interface were monoclinic. The structure of the Cu 3 Sn/Cu interface exhibited special crystallographic relationships after aging, that is [ 2 1 ‾ 1 ‾ 6 ] C u 3 S n / / [ 1 ‾ 01 ] C u and (0 2 ‾ 20) C u 3 S n / / (404) C u . The mismatch of the crystal plane spacing between the (0 2 ‾ 20) C u 3 S n and (404) Cu crystal planes was 0.959%. In this study, monoclinic Cu precipitated at the Cu/Cu 3 Sn interface in the form of particles but did not produce a layered structure. • During aging, the Cu 3 Sn and Cu grain phases were formed at the interface. However, the fine Cu grains grown at the Cu/Cu 3 Sn interface were monoclinic. • The Cu 3 Sn/Cu interfacial structure exhibited special crystallographic relationships of [ 2 1 ‾ 1 ‾ 6 ] C u 3 S n / / [ 1 ‾ 01 ] C u and (0 2 ‾ 20) C u 3 S n / / (404) C u after aging. • The calculated lattice mismatch of crystal plane spacing between the 0 2 ¯ 20 C u 3 S n and (004) C u crystal planes was α ≈ 0.959%, which facilitated the formation of the interface between the Cu and Cu 3 Sn phases. [ABSTRACT FROM AUTHOR]

This study investigated the effect of elemental crystal Ge or/and GeO 2 doping on the microstructure and varistor properties of TiO 2 –Ta 2 O 5 –CaCO 3 varistor ceramics, which were prepared via the traditional ball milling–molding–sintering process. X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy demonstrated that co-doping with Ge and GeO 2 changed the microstructure of TiO 2 –Ta 2 O 5 –CaCO 3 ceramics, thereby increasing the nonlinear coefficient and decreasing the breakdown voltage. The optimum doping concentrations of Ta 2 O 5 , CaCO 3 , Ge, and GeO 2 exhibited the highest nonlinear coefficient (α =14.6), a lower breakdown voltage ( E B =18.7 V mm −1 ), the least leakage current ( J L =10.5 μA cm −2 ), and the highest grain boundary barrier ( Φ B =1.05 eV). In addition, Ge and GeO 2 function as sintering aids, which reduce the sintering temperature because of their low melting points. [ABSTRACT FROM AUTHOR]

Recently multi-alloying has been used for optimization of the SnAgCu (SAC) solder. To comprehensively reveal the effects of multi-alloying on mechanical property of the SAC solder, in this study the Sb, Bi, Ni, In and Ce elements were added into the Sn-3.8Ag-0.7Cu (wt%) solder, then the deformation and fracture behaviors of the multi-alloyed SAC solder (MAS) and MAS/Cu solder joint were in-situ observed and compared with the SAC. The results reveal that more intermetallic compounds (IMCs) and some Bi particles are formed in the MAS, while the (Cu,Ni) 6 Sn 5 IMC in the MAS is refined. Due to the solid solution strengthening and precipitation strengthening, yield strength of the MAS increases by about 25 % compared with the SAC. Under tensile stress, severe slip and grain rotation occurs in the SAC solder, while plastic deformation of the MAS is restrained to a high extent by the dispersed particles within it. The MAS fractures in a tearing mechanism without obvious necking, but still shows a relative high elongation (~35 %), and the MAS has superior creep resistance since the dislocation motion and grain rotation are restrained. The deformation mismatch between the MAS and the Cu substrate is less serious, and the IMC at the MAS/Cu interface are less likely to fracture, resulting in a higher tensile strength (~160 MPa). Multi-alloying is recommended to improve the strength and creep resistance of the SAC. • The deformation behaviors of the multi-alloyed SAC solder (MAS) are investigated. • In-situ observation was employed to show the dynamic deformation process. • The grain rotation and strain localization are restrained in the MAS. • The MAS fractures at a strain of 35 % without necking. • The MAS shows much higher creep resistance than the SAC. [ABSTRACT FROM AUTHOR]

[Display omitted] • A model of nucleation and growth of intermetallic compounds during welding was proposed. • The diffusion coefficient decreases exponentially during the nucleation and growth of intermetallic compounds until thin layers are formed. • The diffusion patterns between matrix and different intermetallic compounds are different. In this study, the formation and growth of intermetallic compounds (IMC) at Sn/Cu interface were studied by using the molecular dynamics method of modified embedded atom method (MEAM) potential combined with practical experiments. The formation and growth process models of IMC layer at the initial stage of soldering were improved, and the growth trend and mechanism of IMC layer were analyzed. Further analysis of diffusivity shows that the diffusivity changes exponentially during welding and is related to the nucleation and growth of intermetallic compounds. Thus, this study provides valuable insights for the subsequent study on the initial stage of Sn/Cu interface and Sn/Cu solder joint reliability. [ABSTRACT FROM AUTHOR]

Herein, we prove that alloying of reactive nanoparticles can improve nanoparticles/β-Sn interfacial bonding and influence the solder alloy's melting point. Furthermore, the alloying effect can enhance the creep resistance of solder alloy. 0-0.5 wt% Ag nanoparticles (NPs) were added to Sn3.0Ag0.5Cu (SAC305) solder paste by mechanical stirring for the preparation of composite solder alloys, which were then extracted from the composite solder pastes. The joints were observed by scanning electron microscope and transmission electron microscope. The elementary composition of the prepared alloys was analyzed by electron dispersive spectrometer. The melting properties of alloys were tested by differential scanning calorimeter. The influences of Ag NPs as reactive nanophase on solder microstructure and melting properties were studied. The results indicated the existence of transition layer at the interface between Ag NPs and β-Sn. Additionally, the interfacial bonding improved after Ag NPs converted to Ag 3 Sn NPs. Due to Ag NPs alloying and solder alloy microstructure refinement being affected, melting points of alloys increased with 0-0.2 wt% addition of Ag NPs and decreased with 0.2–0.5 wt% addition. • A transition layer 2–4 nm wide is obtained at "Ag nanoparticles/β-Sn" interface. • Ag nanoparticles are transformed into Ag 3 Sn nanoparticles after welding. • The interfacial bonding of "nanoparticles/β-Sn" interface improves post alloying. • The alloying effect can influence the composite solder alloy's melting point. [ABSTRACT FROM AUTHOR]