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Friction Stir Welding (FSW) was carried out on AA2219-T87 alloy plates with various process parameters. Multiparametric optimization was carried out using Taguchi-Grey Relational Analysis (T-GRA) to determine the most influencing factors on the responses like Ultimate Tensile Strength (UTS) and Yield strength (YS) of AA2219-T87 butt joints. In this work, defect-free welding parameters were selected from the wide range of trial and L18 Taguchi Mixed factorial design was fit to further optimize the parameters by T-GRA techniques. Parameters like tool rotational speed, welding speed and tool profile were varied, tool tilt angle and thrust force were kept constant. The macro and microstructures were examined to correlate with tensile, yield and hardness property to analyze the predominant factor that would improve joint efficiency. Finer grains were found in nuggets when compared to other zones and the grain size was found to decrease from top to bottom due to centrifugal action. Scanning Electron Microscopy (SEM) studies were carried out on fracture tensile specimen to determine the mode of fracture in the different regions. EDS elemental mapping was done in fracture region of the tensile specimen and it was encountered that crack initiation is along the copper-enriched region. Tensile strength was reported to be 73% of the parent metal and optimized parameter combination was observed for tool with taper threaded pin profile that enhances metal flow.

The contemporary trend of cost-saving is the primary motive while studying the relative motion between the material surfaces. Therefore, exceptional surface characteristics are the most desirable features for any material. The rapid emerging surface modification phenomena like Friction Stir Processing (FSP) have proved its potential in the surface engineering applications. In this study, Magnesium–Aluminum–Silicon (Mg–Al–Si)-based AS21A magnesium alloy was examined for the wear characterization in respect with the cast and Friction Stir Processed (FSPed) conditions. FSP, performed at an optimized set of parameters, was utilized to attain the surface modification in the investigated material. In the wear study, cast and FSPed conditions of AS21A specimens were examined on Pin-on-disc apparatus with typical load values ranging from 10–40N. The subsequent investigation involves characterization of worn surfaces through Scanning Electron Microscope (SEM) micrographs, and Energy Dispersive X-Ray Spectrometer (EDS) to understand the accountable wear mechanism. It was found that the FSPed AS21A samples exhibited noteworthy improvement in the wear characteristics at all assessment conditions. FSPed sample showed overall 17% enhancement in the specific wear rate. Also, with an increase in normal load, around 53–55% reduction was observed in the Coefficient of Friction (COF) value. It was established that the morphology of Mg₂Si precipitates had an active contribution in the wear behavior of cast and FSPed AS21A samples. The notable mechanisms found responsible for the wear of samples were adhesion, abrasion, oxidation, delamination and plastic deformation.

In this paper, experimental analysis was performed during micro-electrical discharge machining (micro-EDM) of titanium alloy Ti–6Al–4V (grade 5) using three types of tools viz. copper (Cu) tool, tungsten carbide (WC) tool, and synthetic graphite (Gr) grade three tool. The main process parameters were taken as (a) pulse on time ($T_{\mathrm{\text{on}}}$), (b) pulse off time ($T_{\mathrm{\text{off}}}$), (c) voltage (V), and (d) capacitance (C). The output responses were taken as the material removal rate (MRR) and tool wear rate (TWR). Taguchi method coupled with grey relational analysis (GRA) (L${}_{16}$ orthogonal array) technique was applied to optimize the input process parameters for both the responses. Scanning electron microscopy (SEM) analysis of the workpiece and tool was also performed to investigate the morphology of the machined surface and tool surface. Energy-dispersive spectroscopy (EDS) analysis was performed to investigate the elemental composition of the machined surface. The experimental finding reveals that tungsten carbide is the most suitable tool material for machining the chosen workpiece for obtaining optimal MRR and TWR. The optimum condition for the copper tool was found as 180V, 1000pf, 10$\mu$s ($T_{\mathrm{\text{on}}}$), and 10$\mu$s ($T_{\mathrm{\text{off}}}$). Meanwhile, the optimum parametric condition for tungsten carbide and graphite tools was found to be the same as 240V, 100pf, 20$\mu$s ($T_{\mathrm{\text{on}}}$), and 5$\mu$s ($T_{\mathrm{\text{off}}}$).

An experimental investigation was conducted to evaluate the machinability of a titanium alloy (Ti6Al4V) using copper (Cu), tungsten carbide (WC), and graphite (C) tools. Voltage (V), capacitance (pF), pulse-on time (T_on), and pulse-off time (T_off) were considered as the input machining parameters, whereas the material removal rate (MRR) and tool wear rate (TWR) were considered as the output machining parameters. A Taguchi L${}_{16}$ orthogonal array and gray relational analysis (GRA) were utilized to design and optimize the machining parameters for both responses. Artificial neural network (ANN) analysis was performed to predict the experimental outcomes. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to assess the surface morphology and determine the elemental composition of the machined surface. The results indicated that the optimum machining conditions for the copper tool were 150 V, 1000 pF, 15$\mu$s (T_on), and 15$\mu$s (T_off). However, the optimal machining conditions for the WC were 200 V, 100 pF, 25 $\mu$s (T_on), and 10$\mu$s (T_off), and the optimal conditions for the C were 200 V, 1000 pF, 20$\mu$s (T_on), and 25$\mu$s (T_off), respectively. The highest MRR achieved using the WC tool was 9.4510 mg/s, whereas the TWR of the Cu, WC, and C tools were 1.1039 mg/s, 1.0307 mg/s, and 1.2796 mg/s, respectively. The results showed that machining with the graphite tool had a higher TWR than machining with the Cu and WC tools.

The polycrystalline ceramic Pb${}_{0.5}$Ba${}_{1.5}$BiVO₆ manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature. Qualitative phase analysis and formation of the ceramic were affirmed by XRD analysis. The X-ray powder diffraction pattern of the compound explored at room temperature affirms the single phase formation with double perovskite structure exhibiting rhombohedral phase. Microstructural analysis of the studied compound procured from the Scanning Electron Microscope (SEM) validates the formation of dense microstructures and nonuniformly distributed grains with minimal voids. Compositional analysis was shaped through the Electron Diffraction Spectroscopy (EDS) confirming the absence of contamination of any other metals apart from the mentioned ones. Dielectric (Cr and $tan\delta$) parameters of the compound were studied using the LCR analyzer at different temperatures and wide range of frequencies. The polarization and dielectric study affirms the presence of ferroelectricity in the material with transition temperature much above the room temperature. The tangent dielectric loss of this sample being almost minimal at room temperature attributes it to find applications in different grounds of electronics. Optical equities of the ceramic were further analyzed by the RAMAN, FTIR, UV–Vis and Photoluminescence spectroscopy.