Dissimilar friction stir welding (FSW) of aluminum and magnesium relies on mechanical interlocking and chemical bonding through intermetallic compounds (IMCs) forming at the interface. This study employed optical, scanning electron, and transmission electron microscopy for the microstructural characterization of AA6061/AZ61 welds at the nanoscale, made under optimized conditions. These were then used to explain the resulting mechanical properties. A new orientation relationship, [0110]Mg//[001]gamma, (0002)Mg//(200)gamma, between Mg and Al12Mg17, was identified based on a selected area diffraction pattern. High-resolution transmission electron microscopy revealed that for all three interfaces (Mg-Al12Mg17-Al3Mg2-Al), planes with high atomic density played a crucial role in the nucleation and growth of IMCs. In the stir zone, the microhardness of AA6061 decreased, as the softening effect outweighed the grain refinement's strengthening effect due to the dissolution of strengthening precipitates. This study's ultimate tensile strength (UTS) is 170 MPa, a value attributed to the mechanical interlocking provided by the transitional key-lock interface and a thin 1.4 mu m IMC layer. Additionally, tensile fractures occurred in the Al12Mg17 phase, attributed to its inherent brittleness, which results from the retardation of slip caused by the covalent bonds between Al atoms within the crystal structure. A three-stage fracture mechanism has been proposed to elucidate the failure behavior of the specimens under tensile loading. This study contributes to the current understanding of interface evolution in Al/Mg friction stir welds and offers insights that could be applied to optimize microstructures for improved properties.

The brazing of porous copper foam (PCF) heat exchanger using copper‐based filler of copper‐tin‐nickel‐phosphorus (Cu‐Sn‐Ni‐P) could lead to a corrosion when exposed to an aggressive environment. The research on corrosion of copper‐based fillers and brazed joint interface between substrate and foam were carried out. The cyclic polarization of 10Sn6Ni7P, 9Sn7Ni6P and 4Sn10Ni8P fillers reveal that the corrosion potential ( E corr ) was shifted from less noble to more noble potentials. While corrosion density ( I corr ) shows 10Sn6Ni7P, 9Sn7Ni6P and 4Sn10Ni8P fillers shifted from more negative to more positive potentials. On the other hand, porous copper foam was brazed with copper using copper‐based filler and immersed in 3.5 % sodium chloride (NaCl) for 7 days. Optical microscope (OM) shows a thicker patina layer formation on joining interface of copper/porous copper foam (Cu/PCF) using 10Sn6Ni7P filler after the immersion test. Scanning electron microscope (SEM) and energy‐dispersive x‐ray spectroscopy (EDX) discover a formation of copper chloride (CuCl) on the unclean immersed specimens and a copper (II) oxide (Cu 2 O) compound on the clean immersed specimens. The chloride was found to selectively attack on the copper along the filler's area due to a more noble of copper phosphide (Cu 3 P) compared to copper.

Necking is a crucial phenomenon that can highly affect the mechanical properties and structural integrity of the material, especially in additive manufacturing. To understand the effect of laser power and scanning speed on necking formation between powder particles for SS316L, a study was conducted on the joining of powder particles under various laser parameters. This knowledge is valuable for fine-tuning laser processing parameters across various industrial applications. For this study, Uniweld Laser 3000 was used for the laser joining process. For the laser parameters, laser speeds ranging from 50 mm/s to 150 mm/s and laser powers of 15 W, 20 W, and 25 W were used in this study. The laser process was concentrated explicitly on observing the powder joining process within a single track. It was observed that the necking size increases as the laser power increases and the scanning speed decreases. At 150 mm/s with 150 W, no particle joining was observed as the powder absorbed insufficient energy to undergo the melting process. At different laser powers, the necking growth rate between scanning speeds varies. When laser power was 15 W and scanning speed was 125 mm/s, the neck size increased to 49 µm. The necking increases further to 62 µm, 93 µm, and 100 µm when the scanning speed is reduced to 100 mm/s, 75 mm/s, and 50 mm/s. The same trend can also be observed under higher laser power, but at a different neck growth rate. Analysis of dislocation density for different laser parameters was also performed. It has been found that the highest energy density corresponds to the highest dislocation density, with a value of 2.03×1014 m-2. It can be concluded that a slower scanning speed allows particles to absorb more heat for the melting process, hence increasing the necking size of the particles.

The automotive industry is increasingly adopting lightweight materials to improve fuel efficiency and reduce emissions, with aluminium alloys emerging as a promising option for vehicle weight reduction. This study investigates the formability challenges of dissimilar AA5052-H32 and AA6061-T6 aluminium tailor welded blanks (TWBs) fabricated using low-powered fibre laser welding for potential lightweight automotive applications. Welding parameters included laser powers of 270 W, 290 W and 310 W, paired with welding speeds of 10 mm/s, 15 mm/s and 20 mm/s, to join the dissimilar alloy pair in a butt-weld configuration via successive double-sided welding. Limiting dome height (LDH) tests revealed that the TWBs achieved only 35-40% of base metal formability, with fracture strains below 0.1 for both major and minor deformations. The presence of porosity in the weld zone, including a softening region identified by microhardness testing, contributed to premature failure during formability testing. These findings highlight the challenges associated with forming operations involving low-power laser welded aluminium TWBs and necessitate further research to improve formability and address manufacturing constraints.

In electropolishing, the material removal rate is frequently neglected, as this process is primarily focused on surface finish, and yet, it is crucial for manufacturing metallic sheets. Solutions are required to enhance the material removal rate while maintaining surface quality. This work introduces an electropolishing technique that involves suspending ethanol in an electrolyte solution and employing a magnetic field during machining processes. The Taguchi approach is utilized to determine the ideal process parameters for enhancing the material removal rate of SS 316L electropolishing through a L9 orthogonal array. Pareto analysis of variance (ANOVA) is utilized to examine the four parameters of the machining process: applied voltage, ethanol concentration, machining gap variation, and the magnetic field of the electrolyte. The results demonstrate that the applied voltage, the incorporation of ethanol in electropolishing, and a reduced machining gap significantly increase the material removal rate; however, the introduction of a magnetic field did not notably increase the material removal rate.

The alloy AZ61 has received little research attention when it comes to Al/Mg dissimilar friction stir welding (FSW) for lightweight structural applications, despite having remarkable mechanical and electrochemical properties. This study investigates the weldability, interface evolution, and corrosion characteristics of AA6061/AZ61 in butt joint configuration by designing experiments using response surface methodology. Analysis of variance on mathematical model of the response surface validated its adeptness. Transitions in tool–metal contact conditions were observed with the changing of parameters. Development of interpenetrating features significantly enhanced mechanical interlocking. Constitutive relations have been used to explain the relationship of Al12Mg17 layer thickness and AZ61 grain refinement in stir zone (SZ) with physical parameters. The microhardness gradually decreased from the AA6061 base metal toward the center of the SZ, due to the dissolution of strengthening precipitates. In contrast, when measured from the AZ61 base metal toward the SZ, the hardness increased because of grain refinement. The maximum value of ultimate tensile strength (UTS) obtained is 179 MPa and is limited by Al12Mg17 with accompanied brittle fracture. Corrosion rate was recorded as 6.33 mm/year for AA6061/AZ61 which is lower than that of previously reported studies. The results of this study highlight the potential of AZ61 as a high-performance alloy for Al/Mg FSW, offering enhanced mechanical strength and corrosion resistance.

The difference in the microstructure, texture in the stir zone (SZ) of the AZ31 (Mg-3Al-1Zn, wt.%) alloy after friction stir welding (FSW) and subsequent annealing at 400 °C for 1 h was characterized by scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) measurements at the surface and core regions. The findings indicate that FSW produced grain refinement where the mean grain size decreases from 19 µm (base metal) to 5.1 and 3.5 µm at the surface and core regions, respectively. The c-axis of the grains at the surface region was aligned with the normal direction (<0001>//ND) due to the additional strain of the tool shoulder. In contrast, the core region shows a typical shear texture, where the c-axis tends to be oriented parallel to the welding direction (<0001>//WD). The Vickers microhardness mapping across the SZ revealed that the core region was soften than the surface region due to the dynamic recrystallization and texture weakening. The microstructure of the SZ remains principally deformed after annealing treatment except for the development of massive Mg17Al12 precipitates and the abnormal grain growth of a few grains with <11−20>//WD orientation at the upper side of the surface region. The c-axis of the grains at the surface region was tilted about 10° toward WD, while an inclined <0001>//WD orientation about 30° from WD was developed at the core region. Consequently, the distribution of microhardness values across the SZ was more heterogeneous than the FSW sample. The results were discussed in the light of grain boundary misorientation, dislocation density and the pinning effect of Mg17Al12 precipitates. Additionally, Schmid factor analysis was used to examine the activation of the basal slip mode to characterize the associated mechanical response.

This study comprehensively investigates distortion in components fabricated using Wire Arc Additive Manufacturing (WAAM) and compares three numerical simulation methods validated through experimental analysis. A thin-walled rectangular SS316L component deposited on an S235 substrate served as the demonstrative model. The Thermo-mechanical Method (TMM) utilized Goldak's double-ellipsoid heat source model and isotropic hardening based on the von-Mises yield criterion which incorporates temperature- and strain-rate-dependent material properties determined from chemical composition using advanced materials modelling software. Another two distinct Inherent Strain Methods (ISM) were employed which are one based on traditional Analytical Equations (AE) and another novel Virtual Calibration Test (VCT). While the AE-based ISM implemented the welding shrinkage theorem, the VCT, which eliminates conventional calibration processes using TMM, corrected and iteratively optimized the resulting distortion to inherent strain values using the Nelder-Mead algorithm. Experimental validation was performed through robotic Gas Metal Arc Welding (GMAW) with precisely controlled process parameters aligned with simulations. Component distortions were measured using an industrial 3D scanner with structured blue light technology. Results indicated average vertical distortion errors of 6–7

Ti6Al4V porous scaffolds are designed and fabricated to solve the elastic modulus mismatch between bone and an implant. Bioactive coating is applied on the surface of the implant to improve biocompatibility of titanium implants and form chemical bonds with surrounding bone. Therefore, this study aims to develop a bio-functional coating on Selective Laser Melting (SLM) manufactured porous Ti6Al4V scaffold produced using plasma electrolytic oxidation technique (PEO). Hydroxyapatite (HAp) and fluorapatite (FAp) were formed on the scaffold surface and field emission scanning electron microscopy (FESEM) was used to study the surface morphology and thickness of the coating. The chemical composition of the coatings was investigated by using an energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS). The coating formation was non-homogeneous with Ca/P ratio range of 1.24 to 1.41, approaching ratio of tricalcium phosphate compound. In vitro bioactivity test using a simulated body fluid (SBF) was conducted and the apatite formation on the coating was analyzed. PEO coatings on Ti6Al4V SLM-manufactured porous scaffolds containing fluoride and calcium salt have shown good bioactivity with the apatite formation that can be observed on all coated scaffolds. It was concluded that the combination of bio-functional coating on the surface of the SLM-manufactured porous scaffold provides synergistic effects, which was beneficial in improving the biocompatibility of orthopedic porous metallic implants. Hence, SLM-PEO approach potentially can be adapted to develop a bioactive titanium implant with tunable mechanical properties for orthopedic applications.

This study investigated the effect of low-concentration fumed silica (FS) in polyethersulfone (PES) membranes. The PES/FS blend membrane was fabricated using a wet phase inversion technique as a flat sheet membrane. Scanning electron microscopy analysis revealed improved pore connectivity and rounder middle structures due to the addition of fumed silica. The experimental results indicated that the fabricated membranes fell within the ultrafiltration range, with pure water flux increasing as fumed silica concentration rose. The pure water flux improved by 64% compared to the native PES membrane. Furthermore, the blend membranes exhibited better selectivity, rejecting pepsin and lysozyme 11% and 19% more efficiently, respectively. Although the low concentration of fumed silica had minimal impact on the water contact angles of the membrane surface, all membranes demonstrated hydrophilicity. This cost-effective approach enhances permeability while maintaining separation characteristics, making it suitable for clean water applications.

Welding is described as a technique of fabricate to join two or more segments either similar or dissimilar materials. Welding procedure divided to two classifications, consists of combination welding and strong state welding process. In this research, low power fiber laser welding was used to weld two different metals using lap joint technique. The study focusses on Ti6Al4V and Inconel 600 without filler alloy in between. Influences of laser welding speed (15mm/s up to 21mm/s) and laser power (230W up to 250W) with constant focal distance were examined on the weldment microhardness. The hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM), fusion zone (FZ) and heat-affected zone (HAZ). Results showed that as the welding speed decreases and laser welding power increases, the microhardness at HAZ is the highest followed by FZ. The optimum microhardness was achieved at 240W and 15mm/s. However, the higher the laser power goes, possibility of micro-cracks and void to happen increases which can lead to reduction in microhardness. The conclusion is that optimum laser welding power and welding speed is essential to make sure sound joint can be produced.

This research explores the optimization of epoxy curing parameters to minimize void formation in 3-IC-ChipMAPBGA packages, a subset of BGA packages, crucial components in high-density interconnect applications. The study utilizes a systematic approach involving design of experiments (DOE) assisted by statistical JMP tool to manipulate curing profiles, aiming to achieve void reduction while preserving adhesion properties. Various analytical techniques, including X-ray imaging, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), die shear strength tests, and C-Sam analysis for delamination, are employed to analyze void formation, material characteristics, mechanical properties, and structural integrity. The findings demonstrate that the sample with a 2nd step curing profile, identified as sample#3, which includes a ramp time of 15 min, a 1st step curing temperature of 90 degrees C with a soak time of 20 min, and a 2nd step ramp time of 20 min, exhibits the most favourable outcome in void reduction. This sample shows a notably lower void presence of 3.66 % and the highest die shear strength of 126 MPa. In contrast, the control sample, serving as a reference, displays a void percentage of 7.28 %, nearly twice as high as that of sample#3, and much lower die shear strength of 80 MPa at 25 degrees C. Adopting the curing profile of sample#3 also leads to a substantial 18.75 % reduction in cycle time compared to the control sample. The study highlights the importance of balancing curing parameters to mitigate void formation and maintain optimal mechanical properties, offering valuable insights for improving the reliability of high-density interconnect applications.

Many biomaterials for long-term usage in the body have been developed recently. Biomaterial manufacture and utilisation should prioritise medicinal purposes. After biological prostheses are implanted, human tissues may react to the prosthesis. These responses influence implant biocompatibility and success. Implant applications depend on biomaterial mechanical characteristics. Biomaterial fatigue resistance, elongation, strength, and deformability are crucial for load-bearing hard-tissue implantation. Due to these characteristics, researchers have developed scaffolding, stent, and hard tissue implantation biomaterials for orthopaedic implants. Magnesium, a biocompatible, low Young's modulus material, might replace bone. In pH 7.4–7.6 applications, it corrodes quickly. Thus, bone tissue may not heal before the implants' mechanical integrity is damaged. However, magnesium's slower degradability reduces the release of magnesium ions ( Mg2+ ), hydrogen ions (H2), and hydroxyl radicals (OH−), giving the body time to recover from biodegradation. Alloying, metal–matrix composites, and surface modification may slow magnesium biodegradation. However, the surface composite alteration has benefits. Friction stir–based methods like friction stir processing may be effective for producing magnesium matrix surface composites to alter surface characteristics. This chapter focuses largely on discussing different friction stir–based processes used to modify the surface of the magnesium alloy. These methods may prolong implant usage and retention in humans.

This study used electroless nickel-immersion gold surface finish. The lead free solder used are tin-silver-copper 305 and tin-silver-copper 307 solder alloys. The difference in copper composition will affect the intermetallic compound ' s microstructure after the laser soldering process. The intermetallic compound formation analysis reveals that only (Cu, Ni)6Sn5 was observed at the solder joint interface for both solders after laser soldering. The grain microstructure of tin-silver-copper 305 formed is rounded-shaped and bar-shaped, while tin-silver-copper 307 shapes are oval-shaped and flake-like. However, for cross-sectioned analysis, the intermetallic compound grain microstructure formed at the solder joint formation was (Ni, Cu)3Sn4 and (Cu, Ni)6Sn5 presented in dendrite-like and scale-like shapes. This result shows that copper content in solder composition is directly affected the intermetallic compound grain microstructure. When exposed to the ageing process, the intermetallic compound thickness will increase directly with ageing time. The intermetallic compound thickness for tin-silver-copper 305 was increased from 0.98 mu m to 8.34 mu m while tin-silver-copper 307 was increased from 1.54 mu m to 8.76 mu m. The result also shows that nano-sized of Ag3Sn grain particle was formed on the intermetallic compound surface after an ageing process for both samples, tin-silver-copper 305 and tin-silver-copper 307.

As a promising wastewater treatment technology, ultrafiltration membranes face challenges related to fouling and flux reduction. To enhance these membranes, various strategies have been explored. Among them, the incorporation of nano-activated carbon (nAC) powder has emerged as an effective method. In this study, composite polysulfone (PSF) ultrafiltration membranes were fabricated using nAC powder at concentrations ranging from 0 to 8 wt.%. These membranes underwent comprehensive investigation, including assessments of membrane morphology, hydrophilicity, pure water flux, equilibrium water content, porosity, average pore size, and protein separation. The addition of activated carbon improved several desirable properties. Specifically, the hydrophilicity of the PSF membranes was enhanced, with the contact angle reduced from 69° to 58° for 8 wt.% of nAC composite membranes compared to the pristine PSF membrane. Furthermore, the water flux test revealed that 6 wt.% activated carbon-based membranes exhibited the highest flux, with a nearly 3 times improvement at 2 bar. Importantly, this enhancement did not compromise the protein rejection. Additionally, the introduction of nAC had a significant effect on the membrane’s pore size by improving lysozyme rejection up to 40%. Overall, these findings will guide the selection of the optimal concentration of nAC for PSF ultrafiltration membranes.

The flexibility of Additive Manufacturing (AM) technologies in the metal 3D printing process has gained significant attention in research and industry, which allows for fabricating complicated and intricate Near-Net-Shape (NNS) geometry designs. The achievement of desired characteristics in Wire-Arc Additive Manufactured (WAAM) components is primarily contingent upon the careful selection and precise control of significant processing variables, including bead deposition strategy, wire materials, type of heat source, wire feed speed, and the application of shielding gas. As a result, optimizing these most significant process parameters has improved, producing higher-quality WAAM-manufactured components. Consequently, this has contributed to the overall rise in the method's popularity and many applications. This article aims to provide an overview of the wire deposition strategy and the optimization of process parameters in WAAM. The optimization of numerous wire deposition techniques and process parameters in the WAAM method, which is required to manufacture high-quality additively manufactured metal parts, is summarised. The WAAM optimization algorithm, in addition to anticipate technological developments, has been proposed. Subsequently, a discussion ensues regarding the potential for WAAM optimization within the swiftly growing domain of WAAM. In the end, conclusions have been derived from the reviewed research work.

PurposeDie edge quality with its corresponding die strength are two important factors for excellent dicing quality especially for low-k wafers due to their weak mechanical properties and fragile structures. It is shown in past literatures that laser dicing or grooving does yield good dicing quality with the elimination of die mechanical properties. This is due to the excess heat energy that the die absorbs throughout the procedure. Within the internal structure, the mechanical properties of low-k wafers can be further enhanced by modification of the material. The purpose of this paper is to strengthen the mechanical properties of wafers through the heat-treatment process.Design/methodology/approachThe methodology of this approach is by heat treating several low-k wafers that are scribed with different laser energy densities with different laser micromachining parameters, i.e. laser power, frequency, feed speed, defocus reading and single/multibeam setup. An Nd:YAG ultraviolet laser diode that is operating at 355 nm wavelength was used in this study. The die responses from each wafer are thoroughly visually inspected to identify any topside chipping and peeling. The laser grooving profile shape and deepest depth are analysed using a laser profiler, while the sidewalls are characterized by scanning electron microscopy (SEM) to detect cracks and voids. The mechanical strength of each wafer types then undergoes three-point bending test, and the performance data is analyzed using Weibull plot.FindingsThe result from the experiment shows that the standard wafers are most susceptible to physical defects as compared to the heat-treated wafers. There is improvement for heat-treated wafers in terms of die structural integrity and die strength performance, which revealed a 6% increase in single beam data group for wafers that is processed using high energy density laser output but remains the same for other laser grooving settings. Whereas for multibeam data group, all heat-treated wafer with different laser settings receives a slight increase at 4% in die strength.Originality/valueHeat-treatment process can yield improved mechanical properties for laser grooved low-k wafers and thus provide better product reliability.

Due to their outstanding corrosion resistance, mechanical characteristics and low specific density, AA5083 and AA6061-T6 Al alloys are used in the aerospace, automotive and marine sectors. Joining such dissimilar Al alloys using conventional fusion welding techniques is very challenging. In contrast, laser beam welding (LBW) is a non-conventional welding technique that is promising to weld dissimilar materials. The viability of welding dissimilar AA5083 and AA6061-T6 joints using fibre laser welding are examined herein. The effect of laser power and welding speed on the morphological, microstructural, microhardness and tensile strength of the welded joints was assessed and revealed that increasing welding power resulted in deeper keyhole penetration. Microporosities were formed due to Mg evaporation and shrinkages; however, the existence of these porosities did not show significant effect on the tensile strength. The microhardness values indicate that the welds were harder than the AA6061 and AA5083 base metals. This is explained by the existence of Mg2Si phase in the AA5083-AA6061 dissimilar junction in addition to the grain size circumstances. The fracture examination showed brittle fracture pattern that is regarded to the formation of brittle intermetallic compound (IMC) phases of Mg2Si, in addition to the inter-dendritic brittle phases of other sites as they were frequently inter-granular.

Polysulfone (Psf) ultrafiltration flat-sheet membranes were modified with hydroxyapatite (HA) powder during preparation using the wet-phase inversion method. HA was incorporated to enhance the protein separation capabilities. The asymmetric Psf membranes were synthesized using NMP as the solvent. Through Scanning Electron Microscopy (SEM) analysis, it was revealed that HA was distributed across the membrane. Incorporating HA led to higher flux, the improved rejection of protein, and enhanced surface hydrophilicity. The permeability flux increased with HA concentration, peaking at 0.3 wt.%, resulting in a 38% improvement to 65 LMH/bar. Whey protein separation was evaluated using the model proteins BSA and lysozyme, representing α-Lactalbumin. The results of protein rejection for the blend membranes indicated that the rejection rates for BSA and lysozyme increased to 97.2% and 73%, respectively. Both the native and blend membranes showed similar BSA rejection rates; however, the blend membranes demonstrated better performance in lysozyme separation, indicating superior selectivity compared to native membranes. The modified membranes exhibited improved hydrophilicity, with water contact angles decreasing from 66° to 53°, alongside improved antifouling properties, indicated by a lower flux decline ratio value. This simple and economical modification method enhances permeability without sacrificing separation efficiency, hence facilitating the scalability of membrane production in the whey protein separation industry.