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In this study, Bi, Sb, and Ni were incorporated into Sn3.0Ag0.5Cu (SAC305) solder to enhance its properties. The composite solders SAC305- x Bi-2.0Sb-0.1Ni (x = 2.5, 3.0, 3.5 wt%) were systematically investigated for their microstructure, thermal characteristics, wettability, thermal aging behavior, intermetallic compound (IMC) formation at interfaces, and mechanical properties of solder joints. The results demonstrated that the combined addition of Bi, Sb, and Ni effectively suppressed IMC growth within the solder matrix, leading to microstructure refinement. Increasing Bi content expanded the spreading area, thereby enhancing wettability. During thermal aging, the growth rate of solder joint interfaces decreased as the Bi content increased up to 3.5 wt%. Electron backscatter diffraction (EBSD) analysis indicated that these alloying elements reduce slip and deformation in the Sn matrix of SAC305-3.5Bi-2.0Sb-0.1Ni solder. Moreover, the tensile strength of solder joints consistently increased with the incorporation of these elements. • Adding Bi, Sb, and Ni to SAC305 solder refines microstructure and improves overall properties, including wettability and thermal properties. • Increased Bi content in the solder alloy enhances spreading area and wettability, while broadening the melting range and reducing subcooling. • Higher Bi content decreases the growth coefficient of the solder joint interface during heat aging, forming a "Bi barrier layer. • The alloying elements increase the tensile strength of solder joints, with improved resistance to slip and deformation, transitioning to a mixed fracture mechanism. [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]

Abstract: Formation mechanism of secondary phase in (La,Nb) Codoped TiO2 ceramics varistor were investigated. The (La,Nb) Codoped TiO2 ceramics samples were prepared from anatase TiO2, Nb2O5 and La2O3 oxide powders by a traditional solid-state sintering method. Microstructure, chemistry composition, crystal structure, thermal etched groove and micrograph of in (La,Nb) Codoped TiO2 ceramics were by SEM, EDS, AFM and TEM. Formation mechanism of secondary phase were discussed by point defect thermodynamical analysis, grain boundary energy and materials structure measurement.The results show that secondary phase are originated from segregation of point defects NbTi andTiLa at grain boundaries in (La,Nb) Codoped TiO2 ceramics. The driving force of segregation is the elastic strain energy. The segregated ion nucleate at grain surface or grain boundaries interface with higher energy. The nucleation gradually grow to form secondary phase at during high-temperature sintering. The growth of secondary phase is mainly on crystal planes with higher energy to minimize the materials system energy. [Copyright &y& Elsevier]

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]

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]

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]

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]