Ultrasonic Vibration Power Research Articles

Delaminated structure of Zn-doped TiO2 coatings induced by ultrasound-auxiliary micro-arc oxidation: the influence of ultrasonic power

In this study, two representative ultrasonic vibration (UV) methods were employed to fabricate Zn-doped TiO2 micro-arc oxidation (MAO) ceramic coatings with enhanced corrosion resistance on pure Ti substrate. On the one hand, the surface morphology and chemistry of the coatings are characterized as partially crystallized hydroxyapatite nanoparticles and amorphous bands rich in Ca, P, Zn, and O. On the other hand, the MAO-modified coatings exhibit much greater corrosion resistance than the bare Ti surfaces, showing a reduction in corrosion current density (icorr) by at least an order of magnitude. However, a key finding is that a lower UV power setting of 360 V (named as the TZ-optimized protocols here) surpasses the higher 900 V (named as the TZ-powerful protocols) in terms of corrosion resistance (i.e. icorr =∼1.47×10−8 A/cm2 vs ∼7.85×10−7 A/cm2, respectively) as well as adhesion strength to the substrate (the critical load of ∼6.4 N vs ∼2.9 N, respectively), which can be attributed to the delaminated structure formed at higher UV powers. This work is expected to remind the potential side effect of such delamination in ceramic coatings produced by UV-assisted MAO processes on Ti-based alloys.

Investigating the Influence of Additive Manufacturing and Ultrasonic Coating Parameters on Biopolymeric Scaffold Performance Using Response Surface Methodology.

Triply periodic minimal surface (TPMS) scaffolds have gained attention in additive manufacturing due to their unique porous structures, which are useful in biomedical applications. Unlike metallic implants that can cause stress shielding, polymeric scaffolds offer a safer alternative. This study is focused on enhancing the compressive strength of additive-manufactured polylactic acid (PLA) scaffolds with a diamond structure. The response surface methodology (RSM)-based experimental design was developed to study the influence of printing parameters. The fused deposition modeling (FDM) process parameters were optimized, achieving a compressive strength of 56.2 MPa. Subsequently, the scaffolds were fabricated at optimized parameters and underwent ultrasonic-assisted polydopamine coating. With the utilization of the RSM approach, the study examined the effects of ultrasonic vibration power, coating solution concentration, and submersion time on compressive strength. The optimal coating conditions led to a maximum compressive strength of 92.77 MPa-a 65.1% improvement over the uncoated scaffold. This enhancement is attributed to the scaffold's porous structure, which enables uniform coating deposition. Energy-dispersive x-ray spectroscopy confirmed the successful polydopamine coating, with 10.64 wt% nitrogen content. These findings demonstrate the potential of ultrasonic-assisted coating in improving the mechanical properties of PLA scaffolds, making them suitable for biomedical applications.

Effects of ultrasonic vibration on residual stress distribution and local mechanical properties of AA6061/Ti6Al4V dissimilar joints by resistance spot welding

The joining of dissimilar titanium and aluminum alloys has potential applications in railway and aerospace industries, owing to substantial weight reduction and better economic viability. In this study, the residual stress distribution and local mechanical performance of ultrasonic-assisted resistance spot welding (UaRSW) welds were investigated. The welding current, welding time, and electrode force of the RSW process were set as 9.0 kA, 350 ms, and 1.0 kN respectively, and the frequency and power of ultrasonic vibration were 20 kHz and 800 W. The residual stress was evaluated by X-ray diffraction (XRD) method and numerical simulation, and these methods showed a reasonable match. There was tensile residual stress distributed on RSW welds and UaRSW welds, but the value of residual stress was reduced by about 30% at welding nugget and 20% at heat affected zone (HAZ) with the ultrasonic vibration, the reduction of residual stress in UaRSW welds was attributed to the more uniform temperature distribution and lower plastic deformation resistant of AA6061. The welding peak temperature was decreased from 1673.4 °C to 1584.2 °C with the ultrasonic vibration, resulted from the modified Al/Ti contact surface and reduced contact resistance. The miniature tensile test results showed the improvement of mechanical performance by ultrasonic vibration. The maximum load of welding nugget region increased from 19.6 N to 22.3 N, and the elongation obtained 10% increase. This hybrid welding technique shows a potential to improve the quality of welds with ensured efficiency, which is also simple to realize automation in the manufacturing industry.

Determination of the absorbed acoustic power of longitudinal vibrations by measuring their amplitude in a chosen area of the waveguide system outside the load

The way of determining the acoustic power of longitudinal ultrasonic vibrations going into the load by measuring the amplitude of longitudinal displacements using an electrodynamic sensor installed near the surface of the waveguide rod is considered. Two possibilities of using the developed method of measurement are analyzed in detail. One of them is based on the registration of the value of longitudinal displacements at the constant position of the electrodynamic sensor in two different states of the ultrasound system: with the load disconnected and after the load is connected, i.e. it uses two measurements at different moments of time, when the states of the system differ from each other. Another way uses two measurements of the amplitude of longitudinal oscillations at two chosen points of the oscillatory system, made at the same time. Formulas have been obtained that make it possible to determine the power entering the load from the measured values and other known values of the system parameters. The role of errors, both in the readings of the sensor and in determining its location on the oscillating system, on the accuracy of calculating the value of the power of the ultrasonic oscillations that went into the load is analyzed.

Mechanical behavior and underlying mechanism of nickel-based superalloy during coupling electrical pulse and ultrasonic treatment

Coupling electric pulse and ultrasonic treatment (CEPUT) is a multi-energy field-assisted forming technology that can improve the forming efficiency of materials. The current research focused on the surface modification of materials by CEPUT, lacking the explanation of its coupling mechanism. In this study, Inconel 718 was adopted as the research object to observe the mechanical behavior and microstructure after CEPUT uniaxial tension experiment. The deformation tendency of grain under coupling multi-energy field was described by analyzing the texture evolution and dislocation morphology. The coupling mechanism of ultrasonic vibration and pulsed current was revealed in CEPUT. The experimental results revealed that there was a nonlinear relationship between the increase of flow stress softening efficiency and the increase of ultrasonic energy density and current density. This phenomenon was the macroscopic manifestation of interference between initial ultrasonic vibration and vibration after energy attenuation, which was related to dislocation slip and recrystallization under coupled multi-field. In addition, more efficient path of dislocation slip was demonstrated through the CEPUT. Among them, ultrasonic vibration caused local resistance to rise at the dislocation source and dislocation pile-up, which strengthened the local Joule heating effect; while the pulsed current reduced the activation energy required for dislocation slip near the waning points. This effectively reduced the resistance of dislocation motion near the pinning point, promoting the chance of dislocation crossing and annihilation. Meanwhile, the high temperature caused by pulsed current and local high strain caused by ultrasonic vibration were more favorable to dynamic recrystallization, and the change of grain orientation was more active. The texture strength and grain orientation of the matrix can be effectively controlled by adjusting the input power of ultrasonic vibration and pulsed current.

Application of ultrasonic vibration in magnesium alloy lap welding

In order to enhance the performance of magnesium alloy and galvanized steel welds, ultrasonic vibration was applied to the laser welding process, and the effect of ultrasonic on mechanical properties was verified through experimental methods. The laser welding system for the lap weld seam was designed, and the ultrasonic vibration module and image detection module were added, which can obtain the influence of ultrasonic vibration on the molten pool area. Under the conditions of ultrasonic vibration power of 1000 W and 0 W, the characteristics of the weld pool area, metallographic structure, tensile strength, fracture morphology, hardness, residual stress, wear resistance, and corrosion resistance of the weld specimen were compared. The image data acquisition structure indicated that ultrasonic vibration can effectively reduce the ineffective area of the molten pool and make the energy in the molten pool more concentrated. Under the influence of ultrasonic vibration, the maximum molten pool area decreased to 5.38 mm2, with a variation range of 3.9 %, and the proportion of pores was greatly reduced. Research found that ultrasonic vibration can significantly improve the microstructure characteristics of the fusion welding zone, with an average grain size reduced to 23 μm. The reduction of grain size and refinement of microstructure were beneficial to the improvement of mechanical properties of magnesium alloy joints, with a yield strength increase of 6.5 %. Ultrasonic vibration had little effect on the hardness of the heat affected zone, it can increase the average hardness of the weld zone by more than 5 % and reduce the maximum residual stress by more than 50 %. Under different pressure and friction speed conditions, the maximum wear amount can be reduced by more than 25 %. At the same time, the resistance to oxidation corrosion and electrochemical corrosion also can be improved to a certain extent.

Mechanical properties enhancement of 3D-printed HA-PLA composites using ultrasonic vibration assistance

ABSTRACT 3D-printed HA-PLA composites have attracted much attention because of their excellent biodegradability and osteointegration properties. However, HA particles negatively affect the mechanical properties of the composite parts. In this study, ultrasonic vibration-assisted 3D printing was used to improve the mechanical properties of HA-PLA composite specimens, and the effects of different infill angles and ultrasonic vibration power on the mechanical properties were investigated. The results demonstrated that the degradation and anisotropy of the mechanical properties of HA-PLA composites were alleviated by the use of ultrasonic vibration. By applying the ultrasonic vibration, the tensile and flexural strengths of the 20 wt% HA-PLA specimens fabricated with a 90° infill angle demonstrated the largest improvement of 104.3% and 112.7%, respectively. The high-frequency ultrasonic vibration waves promoted the spreading and fusion of the extruded materials, thereby reducing overlapping voids within the specimens and improving the interface bonding strength, also facilitated the refinement and dispersibility of the HA particles, which inhibited the formation of stress concentrations within the specimens and ultimately improved the mechanical properties. The printing process developed in this study can also be adapted to other particle (or other reinforcement types) reinforced composite to improve their mechanical performance.

Experimental investigation of ultrasonic assisted coating on three-point bending behavior of 3D printed polymeric bone plates for biomedical applications

3D printed Poly Lactic Acid (PLA) bone plates exhibit limited three-point bending strength, restricting their viability in biomedical applications. The application of polydopamine (PDM) enhances the three-point bending strength by undergoing covalent interactions with PLA molecular structure. However, the heavy nature of PDM particles leads to settling at the container base at higher coating solution concentrations. This study investigates the impact of ultrasonic-assisted coating parameters on the three-point bending strength. Utilizing Response Surface Methodology (RSM) for statistical modeling, the study examines the influence of ultrasonic vibration power (UP), coating solution concentration (CC), and submersion time (TIME). RSM optimization recommended 100 % UP, 6 mg/ml CC, and 150 min TIME, resulting in maximum three-point bending strength of 83.295 MPa. Microscopic images from the comparative analysis revealed non-uniform coating deposition with mean thickness of 6.153 µm under normal coating. In contrast, ultrasonic-assisted coating promoted uniform deposition with mean thickness of 18.05 µm. The results demonstrate that ultrasonic-assisted coating induces PDM particle collision, preventing settling at the container base, and enhances three-point bending strength by 7.27 % to 23.24 % compared to the normal coating condition. This study emphasizes on the potential of ultrasonic-assisted coating to overcome the limitations of direct immersion coating technique.

Response surface methodology and machine learning based tensile strength prediction in ultrasonic assisted coating of poly lactic acid bone plates manufactured using fused deposition modeling

Poly Lactic Acid (PLA) based bone plates fabricated using Fused Deposition Modeling have poor mechanical strength which can be improved by biocompatible polydopamine (PDM) coating. However, PDM particles, being heavy in nature, settle at the container bottom with increase in coating solution concentration at the time of bone plate coating using dip coating technique. Thus, the present work aims to witness the effect of ultrasonic assisted coating parameters on tensile strength of coated bone plates. The coating parameters involving power of ultrasonic vibrations, coating solution concentration and immersion time were varied. The standard Response Surface Methodology (RSM) was applied and experimental trials were performed for obtaining tensile strength of bone plates under varied coating parameters. The objective of the present study was to compare the values of tensile strength predicted using RSM and machine learning (ML) models. Based on the obtained experimental values, gradient boosting regression (GBReg), linear regression (LReg) and random forest regression (RFReg) were trained and tested for predicting tensile strength of bone plates. The accuracy and prediction errors corresponding to RSM and ML based models were compared with respect to R2, Mean Squared Error (MSE), Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE). The findings revealed that GBReg exhibited R2, MSE, RMSE and MAE values as 0.9312, 1.7142, 1.2877 and 1.0861 respectively, while RSM showed R2, MSE, RMSE and MAE values as 0.882, 2.13, 1.4595 and 1.258 respectively. RSM model has shown minimum accuracy with high prediction errors amongst the four models. GBReg has outperformed other ML models in terms of their accuracy and error metrics. The present study therefore suggests the application of GBReg based ML model for predicting tensile strength of PDM coated bone plates in response to its accurate and robust prediction performance.

Harvesting and mapping ultrasonic vibration power using semiconducting wire-based tribovoltaic generators

Ultrasonic vibration is an excellent mechanical power source owing to its large power density. Harvesting ultrasonic vibrations has been demonstrated so far through piezoelectric effect, triboelectric effect, and electromagnetic induction. However, the majority of these devices only produce AC output which limits their potential applications. This work demonstrates, for the first time, the conversion of ultrasonic vibration power to DC output using semiconducting wire-based electric generators, in which one or several semiconductor wire/metal junction(s) are employed. A current density of up to 19 µA/cm2 and a peak power density of 5 µW/cm2 can be obtained under ultrasonic vibrations up to 37 kHz. The mapping of the ultrasonic vibrational strength has been achieved, demonstrating the capability of a self-driven powered ultrasonic sensor. The characteristics of individual semiconductor junctions and the series connection of several such junctions are studied using equivalent circuits.

Effect of ultrasonic vibration on residual stress in plasma cladding of iron-based alloy

To explore the effect of ultrasonic vibration power and frequency on the residual stress of single-channel iron-based alloy plasma cladding, the single-factor ultrasonic vibration plasma cladding test was designed, and ten groups of single-channel iron-based alloy cladding samples under different process parameters were studied. The drilling method was used to measure the residual stress of the substrate at the beginning, middle and tail positions of each sample cladding layer. The residual stress of the substrate was analyzed and the significant characteristics of the effect of ultrasonic vibration power and frequency on the residual stress at different positions were explored using variance analysis. The results show that the residual stress is significantly reduced after applying ultrasonic waves. When the ultrasonic frequency is constant and the ultrasonic power is 240 W, the residual stress of the formed sample is the smallest. Compared with the unapplied ultrasonic assistance, the residual stress in the X direction is reduced by 62.56%, and the residual stress in the Y direction is reduced by 63.23%. When the ultrasonic power is constant and the ultrasonic frequency is 28 kHz, the residual stress of the formed sample is the smallest. Compared with the unapplied ultrasonic assistance, the residual stress in the X direction is reduced by 17.23%, and the residual stress in the Y direction is reduced by 19.79%. The ultrasonic power significantly affects the middle part of the substrate, and the ultrasonic frequency significantly affects each point of the substrate.

Impact of ultrasonic vibration power and tool pin profile on mechanical and microstructural behaviour of friction stir welded dissimilar aluminium alloy joints

PurposeThe purpose of this paper is to investigate the impact of ultrasonic vibration (UV) and tool pin profile on mechanical properties and microstructural behaviour of AA7075-T651 and AA6061-T6 joints was analysed.Design/methodology/approachThe joints were fabricated using three different tool pin profiles such as cylindrical, square and triangle. For each tool pin profile, two different UV powers of 1.5 kW and 2 kW were used.FindingsOn both the advancing and retreating sides of the weld, the thermo-mechanically affected zone has the lowest microhardness. In all joints, the tensile fracture locations match to the minimum hardness values. Field emission scanning electron microscope fractography of tensile tested specimens reveals heterogeneous modes of brittle, shear and ductile fracture. Three-point bending analysis was performed to determine the ductility and soundness of the weld joint. The acoustic softening effect of UV, as well as the static and dynamic ratio of tool pin profile, plays an important role in determining the material flow and mechanical behaviour of the joint.Practical implicationsDissimilar aluminium joining fascinates many applications like aircraft, aerospace, automobiles, ship building and electronics, where fusion welding is a very intricate process because of the deviation in its physical and chemical properties.Originality/valueFrom this study investigation, it is found that the square pin profiled tool with 2 kW UV power produces metallurgical defect-free and mechanically sound weld with maximum tensile strength, hardness and bending load of 297 MPa, 151HV and 3.82 kN, respectively.

Influence of ultrasound and extraction conditions on the intensity of extraction of anthocyanin pigment from berry raw materials

The effect of ultrasound and extraction conditions on the degree of anthocyanin pigment extraction from berry raw materials has been studied. It has been shown that the use of ultrasound for extraction allows increasing the anthocyanin pigment yield. The ultrasound-assisted water extraction at 25°C for 30 minutes increases the yield of pigment in aqueous solution by 22 %. The increase in the ultrasound-assisted extraction temperature to 65°C reduces the extraction time down to 15 minutes. It has been shown that the use of ultrasound reduces the extraction degree in 96 % ethanol and in the ethanol/water/hydrochloric acid system and increases the amount of anthocyanin pigment into the solution containing water as an extraction agent. In this case, the use of the ultrasound-assisted extraction reduces the anthocyanin pigment extraction time to 20 minutes with the use of the 96 % ethanol as an extraction agent, and to 15 minutes in an aqueous solution. The study of the ultrasound-assisted extraction effect, as well as the frequency and power of ultrasonic vibrations on the anthocyanin pigment extraction intensity has shown that the indirect ultrasound-assisted extraction (ultrasonic bath) with the ultrasound exposure frequency of 35 kHz and the power of 80 W allows allocating the anthocyanin pigment to the fullest extent possible within 30 minutes. With the direct ultrasound exposure (ultrasonic homogenizer) with the frequency of 20 kHz and the power of 75 W, the extraction time with an aqueous solution is reduced to 15 minutes, and with 96 % ethanol - to 20 minutes.

Microstructure and shear properties of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints under thermal cycling

Through ultrasonic wave assisted Sn2.5Ag0.7Cu0.1RExNi/Cu (x = 0, 0.05, 0.1) soldering test and − 40 to 125 °C thermal shock test, the microstructure and shear properties of Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints under thermal cycling were studied by the SEM, EDS and XRD. The results show that the Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints with high quality and high reliability can be obtained by ultrasonic assistance. When the ultrasonic vibration power is 88 W, the ultrasonic-assisted Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints exhibits the optimized performance. During the thermal cycling process, the shear strength of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had a linear relationship with the thickness of interfacial intermetallic compound (IMC). Under the thermal cycling, the interfacial IMC layer of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints consisted of (Cu,Ni)6Sn5 and Cu3Sn. The thickness of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints was linearly related to the square root of equivalent time. The growth of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had an incubation period, and the growth of IMC was slow within 300 cycles. And after 300 cycles, the IMC grew rapidly, the granular IMC began to merge, and the thickness and roughness of IMC increased obviously, which led to a sharp decrease in the shear strength of the solder joints. The 0.05 wt% Ni could inhibit the excessive growth of IMC, improve the shear strength of solder joints and improve the reliability of solder joints. The fracture mechanism of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints changed from the ductile–brittle mixed fracture in the solder/IMC transition zone to the brittle fracture in the interfacial IMC.

Additive manufacturing of Ti6Al4V parts using ultrasonic assisted direct energy deposition

Directed energy deposition (DED) parts are generated via concentrated energy source by melting powder during layer by layer deposition. The size of grains in structure built parts is determined by the parameters in the DED process. In contrast, the size of grains in structure deposited metal parts is dependent on the mechanical properties. A fundamentally new method of ultrasonic assisted direct energy deposition (UDED) changes the structure of metal of a Ti6Al4V alloy. Varying the frequency and power of ultrasonic vibrations affects the region of interaction of the powder and the laser spot. It is possible to purposefully obtain parts with a uniform or, if necessary, a gradient structure, depending on the requirements. Systematic investigations of the structure were conducted for various frequencies and power levels of ultrasonic vibrations during DED of Ti6Al4V parts. Wear tests at high loads showed that the coefficient of friction parts obtained by UDED were lower than those obtained by DED. These results were related to the fine grain structure and increased microhardness. Load cycling resistance of tested specimens obtained by UDED was twice as high as those obtained by DED. Irregular needles and fine grains of specimens from UDED also indicated that the structure was resistant to cracks.

Microstructure evolution and properties of in-situ ceramic particles reinforced Fe-based composite coating produced by ultrasonic vibration assisted laser cladding processing

Ultrasonic vibration assisted laser cladding processing was employed to fabricate ceramic particles reinforced Fe-based composite coatings. The influence of the ultrasonic vibration on the dilution, profile appearance, microstructure characteristics, and high temperature oxidation resistance of the composite coatings were investigated. Experimental results revealed that the profile roughness of the coatings was reduced by ultrasonic vibration during laser cladding processing, but the dilution of the coating was slightly increased. The heat and mass transfer in laser molten pool was improved by the ultrasonic vibration, resulting in the refining of the microstructure and increasing the amount of ceramics, as well as homogenizing the distribution of ceramics. The composite coating produced by 300 W ultrasonic vibration assisted laser cladding processing not only possessed good wear resistance, but also had high oxidation resistance. However, excessive ultrasonic vibration power increased the tendency of cracks in the coating.

Microstructure and property of Ni/WC/La2O3 coatings by ultrasonic vibration-assisted laser cladding treatment

Ultrasonic vibration was introduced during laser cladding Ni-60%WC-0.8%La2O3 coatings in this study. The microstructure, elemental distribution, and properties of the cladding coatings, as well as the morphology of WC particles were also investigated. Results showed that with WC ceramic particles, the columnar dendrites that formed at the bottom of the cladding coating without ultrasonic vibration were dissolved, crystallized, and aggregated. As ultrasonic vibration was introduced, the dendrites in the cladding coating were disrupted, and the grains were refined. WC particles concentrated at the bottom of the cladding coatings at an ultrasonic power of 600, 700, and 900 W, resulting in obvious degradation in surface hardness and wear resistance. However, when an ultrasonic power of 800 W was applied, improved hardness and wear resistance, which are attributed to the strengthening of precipitated carbides, refined microstructure, and homogenous distribution of WC particles in the cladding coatings, were observed . For laser cladding coatings without ultrasonic vibration, typical characteristics of abrasive and fatigue wear could be found on the wear tracks after a ring-on-disk (ROD) wear test, and flaking pits appeared along the sliding direction. For the composite coatings prepared with different ultrasonic vibration power, typical abrasive wear occurred on the surfaces of the coatings under 600, 700, and 900 W during ROD wear tests, with additional shallow and mild ploughing for that under 800 W.

An experimental study on surface roughness and frictional property of ultrasonic-vibration-assisted milled surface

Ultrasonic-vibration-assisted milling is a variant of conventional milling process. In this study, experimental investigations were carried out to evaluate the effect of process parameters on the average surface roughness of machined surface (of Al6063 alloy). The results were evaluated to understand the effect of process parameters and are explained using the physics of the process. The effect of ultrasonic amplitude on frictional and wettability property of machined bottom surface was also evaluated. With the increase in power of ultrasonic vibration, the surface roughness increased; however, the friction of lubricated machined surface decreased while sliding on a mild steel surface. With the increase in ultrasonic power, the wettability of the surface increased resulting in a better lubrication and consequent reduction of friction.

Effect of ultrasonic vibration on TIG welding–brazing joining of aluminum alloy to steel

Ultrasonic vibration (USV) can optimize the microstructure of the seam and enhance the mechanical properties of the joint; thus, it has been employed to profitably assist Al/steel welding–brazing. The effects of USV on Al/steel welding–brazing joining were investigated. Without the USV treatment, coarse aluminum dendrites, the second phases of Al–Si eutectic and Al3FeSi with large sizes were formed in the joint. Under the USV treatment, the refinement of the aluminum matrix, spheroidization of the Al–Si eutectic, and fragmentation of Al3FeSi were produced, which resulted from the effects of cavitation and acoustic streaming induced by the USV treatment. The maximum value of the tensile shear strength of the ultrasonic–treated joint could be achieved at an optimum ultrasonic vibration power of 0.8 kW, which had ∼30% increment compared with the raw joint, owing to the fine–grained strengthening and dispersing strengthening of Al–Si eutectic and Al3FeSi. The ductile fracture was located in aluminum base metal.

Effect of ultrasonic vibration on the interfacial IMC three-dimensional morphology and mechanical properties of Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu halogen free solder joints

Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu halogen free solder joints were fabricated by an ultrasonic vibration (USV)-assisted soldering process. The effects of the USV power on the three-dimensional (3-D) morphology of the intermetallic compounds (IMC) and mechanical properties of the halogen free solder joints were characterized systematically. Results showed that the root-mean-square roughness (Rrms) and the mean spacing of adjacent peaks of the profile (λave) of the interfacial IMC were linearly correlated with shear strength of the halogen free solder joints. It was more comprehensive to adopt the λave and Rrms evaluation parameters to characterize the relationship between the interfacial IMC 3-D morphology and shear strength of the halogen free solder joints. With increasing USV power, the eutectic microstructure of the solder seam was refined, and the proportion of eutectic microstructure in the solder seam and microhardness increased. When the USV power increased to 130 W, the Rrms and average thickness of the interfacial IMC decreased (decreases of 37.6% and 56.4%, respectively) and the corresponding λave and shear strength of the solder joint increased (increases of 68.7% and 45.8%, respectively). With increasing USV power, the fracture mechanism of the halogen free solder joint changed from brittle fracture to the ductile–brittle mixed fracture, and the fracture pathway transferred from the interfacial transition zone consisting of the solder seam and the interfacial IMC layer to the solder seam.