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The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, the AISI 316L and IN 718 dissimilar weldments exhibited more flash formation on the AISI 316L side. At higher rotating speeds during friction welding, an intermixing zone was created at the weld joint interface due to the material softening and squeezing. The dissimilar welds exhibited distinctive regions, including the fully deformed zone (FDZ), heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and the base metal (BM), located on either side of the weld interface. The dissimilar friction welds, AISI 316L/IN 718 ST and AISI 316L/IN 718 STA, exhibited yield strength (YS) of 634 ± 9 MPa and 602 ± 3 MPa, ultimate tensile strength (UTS) of 728 ± 7 MPa and 697± 2 MPa, and % elongation (% El) of 14 ± 1.5 and 17 ± 0.9, respectively. Among the welded samples, PWHT samples exhibited high strength (YS = 730 ± 2 MPa, UTS = 828 ± 5 MPa, % El = 9 ± 1.2), and this may be attributed to the formation of precipitates. Dissimilar PWHT friction weld samples resulted in the highest hardness among all the conditions in the FDZ due to the formation of precipitates. On the AISI 316L side, prolonged exposure to high temperatures during PWHT resulted in grain growth and decreased hardness. During the tensile test at ambient temperature, both the as-welded and PWHT friction weld joints failed in the HAZ regions of the AISI 316L side.

The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and microstructures, as well as the changes in hardness and tensile properties resulting from friction welding. The joint integrity was studied through various characterization techniques, and no cracks or incomplete bonding was observed. The study found that the dissimilar joints of the AA7075 and AA5083 alloys displayed higher flash formation on the AA7075 side, which has a lower melting temperature compared to the AA5083 alloy. Various zones were identified in the weld region, including the dynamic recrystallized zone (DRZ), the thermomechanically affected zone (TMAZ) consisting of TMAZ-1 (elongated grains) and TMAZ-2 (compressed/distorted grains), the heat-affected zone (HAZ), and the base metal (BM) zone. The rotary friction welded sample AA5083/AA7075-PWHT joint exhibited the highest strength (yield strength (YS): 195 ± 3 MPa, ultimate tensile strength (UTS): 387 ± 2 MPa) among all the other welded conditions, and this may be attributed to the major strengthening precipitates MgZn2 (of AA7075) formed during postweld aging. All dissimilar welds failed in the HAZ region of the AA5083 side due to the formation of coarse grains, indicating the weakest region.

The present study investigated the influence of welding speed on the microstructure, hardness, and tensile properties of the AZ31 Mg alloy gas tungsten arc (GTA) welds that were prepared using alternating current (AC). A microstructural examination of the weld metal and base metal was performed using stereo, optical, and scanning electron microscopy (HR-SEM and EDS) techniques. The microstructure of all fusion zones consists of two parts: a columnar zone, adjacent to the fusion boundary, and equiaxed grains, in the centre of the weld fusion zone. It is shown that the average width of the equiaxed zone present at the centre of the fusion zone increases with increasing welding speed. Metallographic examination shows that the highest welding speed (5 mm/s) results in the smallest average grain size. The welds prepared with high welding speed exhibit an increase in strength, hardness, and ductility compared with other welding speeds, which is attributed to low heat input.

Metastable beta (β) titanium alloy welds typically exhibit low strength and hardness due to their coarse fusion zone (FZ) microstructure. Efforts to improve the mechanical properties of these alloys have been confined to the use of various heat treatment processes as the means to promote α precipitation in the β matrix. The present study employs a novel method of using boron-added commercial pure-Ti fillers in gas tungsten arc welding (GTAW) of the Ti-15V-3Cr-3Sn-3Al metastable β titanium alloy. Microstructural analysis of boron-added welds showed refined prior-β grains and equiaxed dendritic grains with nonlinear grain boundaries. The formation of TiB and consequent microstructural modification of the FZ in the welds prepared using 0.5 wt% boron-added CP-Ti filler contribute to the improvement in the mechanical properties.

The implementation of boronizing in low alloy steel had been implemented tremendously in past years as this method offers excellent surface protection that led to enhancement of hardness and wear of the material. In conjunction to that, few parameters had been recognized as the factor that promotes boron diffusion into the surface of the material which is the selection of boronizing temperature and time. This study concentrated on the effect of pack boronizing on the boride layer thickness of 304 stainless steel which contained high amount of alloying elements. The microstructural analysis and boron layer thickness was measured and observed using optical microscopy and SEM analyzer. The microhardness of the material was measured using Vickers microhardness tester. The results portrayed that boronizing successfully induced boronizing layer containing FeB and Fe2B phases with thickness of 15μm. This resulted in major improvement of the microhardness values with improvement of 5 times compared to non-boronized samples.

Aluminum-silicon (Al-Si) alloys are an important class of materials, alloys which have great interested in wide industries whether in light or heavy industries, due to their superior properties like high strength to weight ratio, corrosion resistance, and excellent castability. The mechanical strength and the effect of modifying alloys have been studied. To evaluate the strength and revealed the structural of these alloys, the Instron tensile and Shimidzu Vickers hardness tester have been employed while the fracture surfaces have been observed by Scanning electron microscope (SEM). From results obtained, the microstructure of Al-Si with TiB2 has much finer microstructure compared to unfine Al-Si alloy. It showed that the eutectic silicon microstructure in Al-Si alloy changed from needles-look or acicular to fine grain size or globular when the added of TiB2. The mechanical studies showed that the ductility of Al-Si alloy was much lower in the absence of grain refiner, TiB2. The tensile strength of unrefined Al-Si and Al-Si with 6 wt.%TiB2 as grain refinement were recorded 275 and 312 MPa respectively. The hardness value for the unrefined Al-Si alloy also shows less compared with Al-Si with grain refiner, 6 wt.%TiB2, which are 74 and 78 MPa. This showed the results were significant improvements in mechanical properties have been obtained with the use of TiB2 as grain refiner to Al-Si alloy.

The investigation of the microstructural development during solidification as well as wear performance of Nb and Mo added hypereutectic WCI hardface deposits with W and V as minor additives was aimed during the study. This would enable the development of the hardface deposits with superior abrasive performance for severe wear applications. The hardfacing alloys were deposited on carbon steel using self-shielded flux cored arc welding (FCAW) technique. Phase formation, microstructural and mechanical properties of hardface deposits were investigated in the as-deposited condition. The microstructural examination showed that the addition of alloying elements to the high-Cr WCI resulted in grain refinement of the primary proeutectic M7C3 (M = Cr and Fe) carbide phase. EDX analysis revealed that the addition of Nb and Mo resulted in the formation of MC (M = Mo and Nb) carbides which resulted in grain refinement and higher wear resistance. Phase investigation of the deposits using XRD analysis shows the existence of M7C3 for all alloys and MC carbides for alloy B, C and D along with the ferrite phase. The main wear mechanism observed for the base high-Cr WCI is abrasive wear, while hardface alloys with alloying addition showed surface delamination which was attributed to the presence of soft phase adjacent to the M7C3 carbides in the microstructure. Among all the alloys, hardface deposits prepared using a filler with 5.5 -Mo, 6 - Nb, 2 - W and 1 - V (wt%) addition showed highest wear resistance due to grain refinement, MC carbide formation and solid solution strengthening by W and V.

The current study has investigated the influence of zirconium (Zr) addition to Mg–3Ca–xZr (x = 0.3, 0.6, 0.9 wt%) alloys prepared using argon arc melting on the microstructure and impression properties at 448–498 K under constant stress of 380 MPa. Microstructural analysis of as-cast Mg–3Ca–xZr alloys showed grain refinement with Zr addition. The observed grain refinement was attributed to the growth restriction effect of Zr in hypoperitectic Mg–3Ca–0.3 wt% Zr alloys. Heterogeneous nucleation of α-Mg in properitectic Zr during solidification resulted in grain refinement of hyperperitectic Mg–3Ca–0.6 wt% Zr and Mg–3Ca–0.9 wt% Zr alloys. The hardness of Mg–3Ca–xZr alloys increased as the amount of Zr increased due to grain refinement and solid solution strengthening of α-Mg by Zr. Creep resistance of Mg–3Ca–xZr alloys increased with the addition of Zr due to solid solution strengthening of α-Mg by Zr. The calculated activation energy (Qa) for Mg–3Ca samples (131.49 kJ/mol) was the highest among all alloy compositions. The Qa values for 0.3, 0.6 and 0.9 wt% Zr containing Mg–3Ca alloys were 107.22, 118.18 and 115.24 kJ/mol, respectively.

Strength and ductility of fusion zone of metastable β titanium alloy welds can be improved by choosing suitable fillers. This paper reports the effects of using CP-Ti filler on the microstructural and mechanical properties of Ti-15-3 weldments. Full penetration autogenous and CP-Ti filler welds were produced by pulsed gas tungsten arc welding. X-ray diffraction analysis revealed small amounts of α-Ti phase in the diffraction pattern obtained for welds prepared using CP-Ti filler. Transmission electron microscopy analysis showed presence of grain boundary and intragranular α in the fusion zone of the welds prepared using CP-Ti filler. The welds prepared with CP-Ti filler showed higher hardness, higher UTS and lower % strain compared to autogenous welds.

Mechanical properties of as-cast beta titanium (β-Ti) alloy can be improved by grain refinement and formation of insoluble precipitate. This paper reports the effect of carbon (C) addition on microstructure and hardness of cast Ti–15V–3Cr–3Sn–3Al (Ti-15-3) samples prepared by argon arc melting. X-ray diffraction analysis of C added as cast Ti-15-3 samples revealed the presence of β-Ti and TiC phases. Scanning electron microscope analysis revealed eutectic TiC precipitates in C added Ti-15-3 samples while a reduction in grain size was observed with increasing carbon addition. Inoculation effect due to TiC and growth restriction by C for β phase resulted in decreased grain size. Hardness of C added Ti-15-3 alloys increased with the increased carbon content of the sample. The improvement in hardness was contributed by grain refinement and the formation of TiC precipitates in the samples.

The present study has investigated the influence of calcium process control agent on the microstructure and mechanical properties of powder metallurgy processed samples fabricated by milling and spark plasma sintering technique. The microstructure of spark plasma sintered Ti-6Al-4V with 0.3 wt% Ca (Ti-6Al-4V-0.3Ca-M) samples revealed fine grain structure compared to sintered unmilled (Ti-6Al-4V-UM) samples. The average grain size values of sintered Ti-6Al-4V-0.3Ca-M and Ti-6Al-4V-UM samples are 8 and 60 μm, respectively. The spark plasma sintered Ti-6Al-4V-UM exhibited a yield strength (YS) of 875 ± 10 MPa, ultimate tensile strength (UTS) of 1057 ± 2 MPa, and % elongation (% El) of 15 ± 2. The spark plasma sintered Ti-6Al-4V-0.3Ca-M exhibited higher YS of 964 ± 9 MPa, UTS of 1153 ± 7 MPa, and lower % El of 6 ± 1 when compared to mill annealed Ti-6Al-4V alloy (YS 899 MPa, UTS 978 MPa and %El 15). The higher strength of Ti-6Al-4V-0.3Ca-M sintered samples could be attributed to the fine grain structure and the presence of interstitial elements in the matrix. In contrast, the lower strength of Ti-6Al-4V-UM can be ascribed to its coarse grains.

Microstructural and impression creep properties of hot pressed bulks made from unmilled AlMg5 powders, milled AlMg5, and AlMg5 powders milled with 0.5 vol% of Al2O3 nanoparticles are investigated. Microstructural, high-temperature impression creep, and high-temperature tensile properties investigation is carried out. Activation energies and stress exponent values are determined from the steady state creep rate obtained at different temperatures and creep stresses. AlMg5–0.5 vol% Al2O3 samples display superior strength values at 298 K compared to unmilled AlMg5 and milled AlMg5 samples. However, AlMg5–0.5 vol% Al2O3 nanocomposite exhibits higher creep rate and tensile elongation with a decrease in strength at 473 K due to activation of grain boundary sliding mechanism.

Reported work focuses on the effect of morphology of the Fe-rich intermetallic phases on the machinability of Al-alloy containing >2wt.% Fe, obtained from automotive scrap. Effect of Mo addition on the microstructure, high-temperature impression creep and thereby the machinability of the Al-recycled alloy were studied. The machinability of the recycled alloy was estimated by investigating the built-up-edge (BUE) and surface roughness (Ra). SEM-EDS and TEM-SADP studies have shown that the crystal structure (BCC) of the Al8Fe2Si phase remained unchanged; however, Mo replaced few Fe atoms with little effect on the lattice dimension. It has been found that the addition of Mo to the recycled alloy suppresses the formation of β-phase (Al5FeSi) by suppressing the peritectic transformation of α (Al8Fe2Si) phase. Such suppression is found to improve the high-temperature creep resistance and the machinability with the increase in the Mo addition level.

Glass samples with composition xSrO-10PbO-(90-x)B 2 O 3 (x = 20, 25, 30, 35, 40 and 45) were prepared by melt-quenching method to elucidate the elastic behaviour due to borate anomaly. Structural investigation of glass samples were carried out by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy while elastic properties were studied by measuring both longitudinal and shear velocities using pulse-echo method at 5 MHz frequency. FTIR analysis revealed the presence of BO 4 and BO 3 vibration groups. Addition of SrO has resulted in increased ultrasonic velocities, elastic moduli ( C L , μ , K and Y ), hardness ( H ), Debye temperature ( θ D ) for SrO content up to 30% but decreased for higher SrO addition. The fraction of the four coordinated boron atoms (N 4 ) values, calculated from FTIR spectra increased for x ≤ 30 mol% followed by decrease at x > 30 mol%. Quantitative analysis of ultrasonic data using the bulk compression and ring deformation models showed reduction in the ratio of calculated bulk modulus to the experimental bulk modulus, K bc / K e for x ≤ 30 mol% indicating decreased ring deformation in borate anomaly region.

High Entropy Alloy (HEA) with at least 5 elements with equimolar ratios were developed to investigate the characteristics of Zr added in FeNiAlCoCrZrx (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0). HEAs were prepared by arc melting technique in Ar atmosphere and were remelted five times to ensure homogeneity. The microstructure and phase constitution of these alloys are examined by X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM). The results show that addition of Zr to FeNiAlCoCr HEA resulted in multiple solid solution phases viz., BCC1, BCC2, FCC1 and FCC2 as evidenced by XRD patterns. Furthermore, presence of both BCC and FCC phases at higher Zr additions suggests that Zr did not preferentially promoted the solidification of either BCC or FCC phase. It can be observed from the FESEM micrographs that with different Zr additions, solidified microstructures of FeNiAlCoCrZrx alloys varied between completely eutectic microstructures to proeutectic and eutectic phase mixtures. From FESEM micrographs it can be suggested that different Zr contents have resulted in different solidification modes. Hardness of Zr added samples is higher compared to base HEA which is FeNiAlCoCr. It was observed that hardness values are higher when proeutectic phases were present compared to completely eutectic FeNiAlCoCrZr alloy (x=0.1).

In the present study, powder metallurgy processed unmilled AlMg5, milled AlMg5 and milled AlMg5-0.5 vol% Al2O3 nanocomposite have been successfully friction stir welded (FSW). The effect of friction stir welding on the evolution of weld microstructures; hardness and tensile properties were studied and discussed in detail. FSW of unmilled AlMg5 resulted in significant grain refinement and strain hardening in the nugget zone induced by the thermo-mechanical processing, thereby increasing the stir zone hardness and tensile strengths to 100 HV and 324 MPa when compared to 80 HV and 300 MPa of base metal, respectively. In contrast, the FSW of milled AlMg5 and milled AlMg5-0.5 vol% Al2O3 samples showed a reduction in UTS values to 375 MPa and 401 MPa in the stir zone compared to 401 MPa and 483 MPa of respective base metal values. Transmission electron microscopic (TEM) investigation of weld stir zones revealed the homogenous distribution of Al4C3 nanophases in milled AlMg5 and Al2O3 nanoparticles in milled AlMg5-0.5 vol% Al2O3 samples throughout the aluminium matrix. It was revealed that the pre-stored energy from the prior ball milling and hot pressing processes, higher deformation energy and grain boundary pinning effect due to the presence of reinforcement particles has resulted in a higher recrystallization tendency and retarded grain growth during FSW of milled samples. The welds prepared with milled AlMg5-0.5 vol% Al2O3 exhibited higher hardness and tensile strength in the stir zone when compared to all other conditions which was attributed to Hall Petch effect due to fine grain size and Orowan strengthening effect due to Al2O3 reinforcements.

Phase formation, microstructure, and hardness properties of FeCrNiMnCoTax and Al0.5 FeCrNiMnCoTax high-entropy alloys (HEA) have been investigated and reported. In this study, FeCrNiMnCoTax and Al0.5FeCrNiMnCoTax high-entropy alloys (HEA) were synthesized using arc-melting technique in argon (Ar) atmosphere from high purity elements (x in molar ratio, x=0.2, x=0.4 and x=0.6). Ingots from arc-melting were homogenized for 24h at 900°C in Ar atmosphere. Dominant dendritic and inter-dendritic phases were identified from the electron micrographs of these HEA. The area of inter-dendrite region increased for both FeCrNiMnCoTax and Al0.5FeCrNiMnCoTax alloys with the increasing of Ta content. The major phases in both FeCrNiMnCoTax and Al0.5FeCrNiMnCoTax alloys were identified as FCC and BCC solid-solutions. Addition of Al in Al0.5FeCrNiMnCoTax alloys has resulted in precipitation of a minor phase which was identified as FCC-TaCr2 Laves phase. As the Ta content increased, hardness of FeCrNiMnCoTax and Al0.5FeCrNiMnCoTax alloys increased from 200.34 Hv to 345.10 Hv and 385.22 Hv to 570.86 Hv respectively. Furthermore, presence of Laves phase in Al0.5FeCrNiMnCoTax alloys has resulted in higher hardness values compared to Al free sample, and this higher hardness could be attributed to precipitation strengthening effect by Laves intermetallic phase formation.

Tensile and wear properties of aluminium (Al) based metal matrix composites (MMCs) was prepared by added titanium diboride (TiB2) with in-situ technique by salt route. The salts used in this research were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). Nanocomposite samples were prepared by casting technique associated with incorporating 3 and 6 wt.% of TiB2 into matrix of Al-6wt.%Cu. Instron and wear tests machine were used to characterize the tensile and wear Al-Cu alloys properties. Results showed that increase in TiB2 content gave the high properties of tensile and wear behavior. The study indicates that TiB2 particles have giving improvement the wear performance of the Al–6wt.%Cu alloy. For a constant load and sliding speed, the wear rate decreases as a function of amount of TiB2 in the composite. The wear rate decrease with increasing in wt.% TiB2 particles for the all loads applied. However, addition of TiB2 particle to the Al–6 wt%.Cu matrix has show the coefficient value of wear decreases regardless of applied load. Study of the wear surfaces both alloy and composites by optical microscope suggests that the improvement in wear resistance is mainly due to the formation of finer groove or debris by content of TiB2.

The aluminium-silicon (Al-Si) alloys, based on the Metal Matrix Composites (MMCs) system are widely used in light-weight constructions and transport applications requiring a combination of high strength and ductility. A grain refinement plays a crucial role in improving characteristics and properties of Al-Si alloys. In this investigation, titanium diboride (TiB2), scandium (Sc) and strontium (Sr) elements were added to the aluminium alloys for grain refinement of the alloy. This study focused more on how to improve the microstructure of the alloy by adding some inoculants that mentioned above. The TiB2content was fixed at 6wt.% while 0.2-0.8wt.% Sc and Sr contents were chosen in this investigation. Characterizations of the alloy by using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) were conducted to identify how the inoculants existence affected the phase composition and the microstructure of composite. From the results obtained, it showed that the hardness of the alloy increased compared to Al-Si-TiB2 -Sr alloy without addition of Sc. The study discovered that the inoculants can act as a grain refiner due to decrement size of dendritic structure and also responsible for the mechanical properties improvement.

Aluminium-copper (Al-Cu) alloys is the one of most Metal Matrix Composites (MMCs) have important high-strength Al alloys. The aluminium (Al) casting alloys, based on the Al-Cu system are widely used in light-weight constructions and transport applications requiring a combination of high strength and ductility. In this research, Al-Cu master alloy was reinforced with 3 and 6wt.% titanium diboride (TiB2) that obtained from salts route reactions. The salts used were were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). The salts route reaction process were done at 800 °C. The Al-Cu alloy then has characterized on the mechanical properties and microstructure characterization. Salts spray fog test and Gamry-electrode potentiometer instruments were used to determine the corrosion rate of this alloys. From results obtained, the increasement of 3wt.%TiB2 contents will decrease the value of the corrosion rate. In corrosion test that conducted both of salt spray fog and Gamry-electrode potentiometer, the addition of 3wt.%TiB2 gave the good properties in corrosion characterization compare to Al-Cu-6wt.%TiB2 and Al-Cu cast alloy itself. As a comparison, Al-Cu with 3wt.%TiB2 gave the lowest value of corrosion rate, which means alloy has good properties in corrosion characterization. The results obtained show that in-situ Al-Cu alloy composites containing the different weight of TiB2 phase were synthesized successfully by the salt-metal reaction method.

Titanium (Ti) and its alloys are widely used in medical applications due to its superior mechanical properties and biocompatibility. Hydroxyapatite (HA), due to its similarity with teeth and bone material, is also widely used in clinical applications and orthopaedic implant manufacture. In this study, composite powers containing titanium with different wt % of HA were coated on stainless steel substrate using high velocity oxy-fuel (HVOF) spray technique. These Ti+HA coatings were characterized using XRD technique to indentify phases present in the coating. Small amount of oxide phases were identified apart from the original Ti and HA in the coatings during XRD analysis. The microstructure analysis of the coating surface using FESEM and EDX revealed dense and homogeneous coatings along with few well distributed pores.

CaCu3Ti4O12(CCTO) is well known to have colossal dielectric constant in the range of 105.It is widely accepted that this phenomenon may be attributed to internal layer barrier capacitance (IBLC) model. The dielectric properties of CCTO were reported to be strongly dependent on the processing conditions and grain size. In this work, CCTO samples with different grain sizes were produced by varying sintering temperature in order to investigate IBLC effect on dielectric properties of CCTO. The samples were sintered at four different temperatures, (T=1100°C, 1050°C, 1000°C and 950°C). Dielectric measurements were carried out for the samples in the frequency range of 102– 106Hz using impedance spectrometer. Electron micrographs showed that increasing temperature promoted the grain growth of CCTO while sintering. The internal crystalline defects are seen to play major role by increasing the grain conductivity in dipole formation and increased the dielectric constant of the samples.

Aluminium based metal matrix composites (MMCs) have better properties and performance. They are commonly used in transport applications which require combinations of high strength and ductility. They are quite attractive due to their low density, capability to be strengthened by precipitation, good corrosion resistance, high thermal and electrical conductivity. Grain refinement plays a crucial role in improving characteristics and properties of aluminium-silicon (Al-Si) alloy. In this investigation, scandium (Sc) and strontium (Sr) elements were added to aluminium-silicon-titanium diboride (Al-Si-TiB2) alloy for refinement of grains. The compositions of 93 wt.% Al-Si, 6 wt.% TiB2, 0.5 wt.% Sc and 0.5 wt.% Sr were melted into induction furnace. Then the composites have been characterized on the mechanical properties and microstructure characterization. Instron tensile machine and vickers hardness tester were used to characterize the mechanical properties of the composite alloy. Microstructure and phase composition were characterized by Field Emission Scanning Electron Microscope (FESEM) and X-ray Diffraction (XRD). From the results obtained, addition of Sc and Sr, into Al-S-TiB2 improved the tensile strength and hardness of composite alloy. Results also showed that the inoculants addition able to enhance the refinement of grains and escalate the values of hardness and tensile strength of Al-Si-TiB2 composite. Mechanical properties related much on the microstructure as it can be seen that the addition of grain refiners produced much higher value of mechanical properties.

Microstructural and mechanical properties beta Titanium (β-Ti) weldments can be improved by grain refinement and formation of insoluble precipitates in the weld. This paper reports the effect of Boron (B) and Carbon (C) addition to Ti-15V-3Cr-3Sn-3Al (Ti-15-3) fillers on the microstructural and mechanical properties of Ti-15-3 gas tungsten arc weldments. X-ray diffraction and scanning electron microscopic analysis revealed the presence of β-Ti phase in the weldments prepared without the filler modification, while additional TiB and TiC phases are observed in the weldments prepared with fillers modified with B and C, respectively. B and C addition to the fillers has resulted in the grain refinement of the weldments and the grain size reduction is seen to be higher with the increasing B and C addition. The formation of TiB, TiC and growth restriction effect due to the presence of B and C in the filler resulted in the decreased grain size of the β-Ti weldments. Mechanical properties such as hardness and tensile strength improved as the amount of B and C addition increased. The improvement of mechanical properties is contributed by the grain refinement and the formation of TiB and TiC precipitates in weldments.

Duplex stainless steels (DSSs) are complex materials and they have been widely used in the marine environment and gas industries, primarily offering a better resistance of pitting corrosion and good mechanical properties. In the present work, the effects of heat treatment on duplex stainless steel (DSS) weld overlay samples that were heat treated at three different temperatures, namely 350 &deg, C, 650 &deg, C, and 1050 &deg, C, and followed by air cooling and water quenching were studied. Stress relief temperature at 650 &deg, C had induced sigma phase precipitation in between delta ferrite and austenite (&delta, /&gamma, ) grain boundaries, resulting in the loss of corrosion resistance in the weld metal. Interestingly, post weld heat treatment (PWHT) test samples that were reheated to solution annealing temperature had shown no weight loss. The ferrite count determination in the region of weld metal overlay increased at hydrogen relief and decreased at stress relief temperatures due to slow cooling, which is more favorable to austenite formation. The amount of ferrite in the weld metals was significantly reduced with the increment of solution anneal temperature to 1050 &deg, C because of sufficient time for the formation of austenite and giving optimum equilibrium fraction in the welds.

Microstructural development, post-weld ageing response and mechanical properties of gas tungsten arc and CO2 laser welded Al-6 %Cu (AA2219) alloy were investigated in the present study. The fusion zone of laser weld consists of three parts: the fine grains in the middle part, the columnar zone and equiaxed zone adjacent to fusion boundary. In contrast, fusion zone of gas tungsten arc weld consists of two parts: the columnar zone in the middle part and the equiaxed zone adjacent to fusion boundary. The size of the equiaxed grains in the fusion zone was the least in the laser welds when compared to gas tungsten arc welds. Laser welds have exhibited higher hardness, post weld ageing response, yield strength, ductility and fatigue strength when compared with gas tungsten arc welds. Fine equiaxed grain morphology and discontinues eutectic distribution in the laser weld fusion zone could be attributed to the improved tensile and fatigue properties of laser welded samples. ‘Thermal pinning effect’, due to non isothermal conditions, has arrested grain growth in heat affected zone in spite of temperatures close to the melting point of aluminum in heat affected zone.

CaCu3Ti4O12 (CCTO) is well known to have colossal dielectric constant in the range of 105. However, CCTO has considerably high dielectric loss values (tanδ > 0.1) at room temperature and 1 kHz. In this work, addition of glass to CCTO was suggested in order to improve its dielectric properties. The effect of V2O5–TeO2 (VT) glass addition on microstructure and dielectric properties of CCTO ceramics were investigated. Dielectric measurements were carried out for (1 − x) CCTO-(x) V2O5–TeO2 (x = 0, 0.03, 0.05, 0.10) samples in the frequency range of 102–106 Hz using impedance spectrometer. Electron micrographs showed that low melting VT glass addition facilitated the grain growth of CCTO. As VT glass amount increased, dielectric constant decreased. The drop, though within reasonable values (~105), may related to the presence of grain boundary glassy phase which itself has low dielectric constant. However, the dielectric loss of the composite has decreased after VT glass addition. The low melting V2O5–TeO2 glass aided in liquid phase sintering and improved the grain boundary resistance which resulted in decreased leakage currents.

Properties of pure metals can be enhanced by alloying with other metallic or non-metallic elements according to the need. However, as multiple alloying elements in an alloy may lead to the formation of many intermetallic compounds with complex microstructures and poor mechanical properties, new types of metallic alloys called high entropy alloys with at least five elements with equimolar ratios were developed. In this study, FeNiAlCuCrTi x Nb y (x, y = 0, 0.5, 1.0, 1.5) alloys have been prepared using Ar arc melting technique. Microstructural studies using scanning electron microscope and XRD showed that Ti addition promoted secondary BCC2 phase whereas, Nb acted as FCC stabilizer. Samples with combined Nb and Ti addition showed FCC1 and FCC2 structure with Nb-rich FCC2 dendritic phase as dominant phase. Though, individual Nb and Ti additions have resulted in increased hardness, combined additions have resulted in highest hardness of 797 HV under 1 kg load.

In this study, the effect of Zr addition on phase formation, microstructure, and hardness of FeCrNiMnCoZr x and Al0.5FeCrNiMnCoZr x were investigated. High entropy alloys (HEA) were synthesized using arc melting technique in argon (Ar) atmosphere (x = 0, 0.1, 0.2, 0.3). Ingots were homogenized for 24 h at 900 °C in Ar atmosphere. Phase formation, microstructure and hardness of HEAs were investigated using field emission scanning electron microscope, X-ray diffraction and Vickers microhardness tester. Electron micrographs of HEAs showed majorly dendritic(DR) and interdendritic(ID) phases. For both FeCrNiMnCoZr x and Al0.5FeCrNiMnCoZr x alloys, amount of ID phases is seen to increase with increased Zr content. Aluminium containing HEAs showed fine needle-shaped precipitates dispersed throughout the matrix phase. XRD results confirmed the presence of mixed FCC/BCC phases in FeCrNiMnCoZr x alloys and BCC as majority phase in Al0.5FeCrNiMnCoZr x alloys. As the Zr content increased, hardness of HEA increased.

Wear is one of the major problems faced in industry that reduces the life of industrial components and increases the operating costs. Therefore, hardfacing is widely employed by engineers to minimize components’ wear, in which single or multiple layers of hard material that mainly consists of carbides deposited on the base metal. However, these carbide-based materials suffer from solidification cracking due to lack of ductility. In this study, titanium carbide (TiC) reinforced alloy steel deposited using self-shielded flux cored arc welding technique. The microstructure and phase analysis in the hardfaced deposit by scanning electron microscope, energy dispersive x-ray and X-ray diffractometer revealed that the microstructure consists of finely distributed TiC within matrix of martensite and some retained austenite. Microhardness test and pin-on-disk wear test had shown that the clad deposit posses better hardness and wear resistance. Retained austenite formation and TiC precipitation were discussed in detail and correlated with the mechanical properties.

Addition of hydroxyapatite (HA) can enhance the bioactivity of the common metallic implant due to its similarity with natural bones and teeth. In this investigation, high velocity oxy-fuel (HVOFT) technique was used to deposit titanium-hydroxyapatite (Ti-HA) composite on stainless steel substrate plate with different percentage of HA for biomedical applications. The aim of this research is to investigate the mechanical properties of Ti-HA coating such as hardness, adhesion strength and wear behaviour. The hardness and strength was determined by using SHIMADZU-microhardness Vickers tester and PosiTest AT portable adhesion tester respectively. The wear test was performed by using pin-on-disk equipment and field emission scanning electron microscope (FESEM) used to determine the extent of surface damage. From the results obtained, mechanical properties such as hardness and adhesion strength of titanium (Ti) coating decreased with the increased of HA contents. Meanwhile, the coefficient of friction of Ti-10% HA coating shows the highest value compare to others as three-body abrasion had occurred during the test.

The refinement in weld metal grain size and shape results in both improved mechanical properties (ductility and toughness) as well as a significant improvement in weldability. In the present study, the influence of scandium (Sc) additions to the fillers on the structure and mechanical properties of AA6082 gas tungsten arc (GTA) weldments were investigated. Controlled amounts of scandium as grain refiner were introduced into the molten pool of AA6082 by pre-deposited cast inserts (AA4043 and AA5356) by GTA welding. Full penetration GTA welds were prepared using alternating current (AC). It was observed that grain size decreased with increasing amounts of scandium. The grain refinement is mainly caused by the Al 3 Sc particles, which act as heterogeneous nucleation of α-Al grains. It has been shown that welds prepared with AA5356 cast insert exhibited high strength and ductility when compared with other welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, strength and ductility. Post-weld aging treatment resulted in improved tensile strength and hardness of the weldments and this aging response could be attributed to the weld dilution from the base metal. The slow diffusion of Sc in Al matrix and stability of Al 3 Sc precipitates at elevated temperatures were suggested to be responsible for the improved high temperature yield strength of welds made from Sc modified fillers.

This paper presents the characterization results of Zinc Oxide (ZnO) nanoparticles prepared by mechanochemical processing using different moles of diluents. ZnO nanoparticles of different crystallite size were synthesized by milling the precursor powders for 5 hours in a high energy ball mill with Zirconia media. NaCl was added as process control agent (PCA) to control the reaction kinetics, as final particle size of nanoZnO is influenced by the reaction rate. X-ray Diffraction (XRD) data was used to compute and analyze the crystallite size of nanoparticles and also to analyze the progress of reaction during milling process. Field Emission Scanning Electron Microscope was employed to analyze the particle morphology and size distribution of ZnO nanoparticles. Ultraviolet Visible (Uv-Vis) spectroscope was employed to analyze the optical absorption of ZnO nanoparticles. Tauc plots were used to determine the energy gap of the ZnO nanoparticles. Crystallite size values of ZnO nanoparticles are seen to be influenced by the amount of PCA and heat treatment. ZnO nanoparticles with a range of Eg (3.1 to 3.14 eV) were obtained depending on process parameters and an inverse relationship was observed between the crystallite size and the energy gap of the ZnO nanoparticles.

Grain refinement of weld metal plays a vital role in improving mechanical properties (ductility and toughness) as well as weldability. The present study has investigated the influence of Tibor™ additions on the structure and mechanical properties of AA6082 gas tungsten arc (GTA) weldments. Controlled amounts of Tibor™ grain refiner (containing Ti and B in a ratio of 5:1) were introduced into the molten pool of AA6082 by pre-deposited cast inserts (AA4043 and AA5356) under different welding conditions by GTA welding. Full penetration GTA welds were prepared using alternating current (AC). It was observed that grain size was decreased with increasing amounts of Tibor™. The grain refinement is mainly caused grain nucleation associated with constitutional undercooling during solidification. It has been shown that welds prepared with 5356 cast insert exhibited high strength and ductility when compared with other welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, strength and ductility.

Mechanochemical processing was reported to introduce lot of crystal defects which can significantly influence emission properties. Nevertheless, to the best of our knowledge, there are no reports on effect of mechanochemical processing on emission properties of transition metal ion doped ZnO. In this study, Zn 1− x Mn x O nanoparticles with different Mn content ( x =0, 0.02, 0.04, 0.06, 0.08, and 0.1) were prepared by mechanochemical processing to study the effect of Mn doping and processing on emission properties. Confirmation of nanoparticles size and nanocrystalline nature of hexagonal wurtzite ZnO structure is carried out using transmission electron microscopy (TEM) and selected area electron diffraction (SAED), respectively. The samples were also characterized using Fluorescence Spectroscope before and after heat-treatment. The emission studies revealed that blue emission intensity is stronger compared to UV and green emission in contrast to the earlier reports, where other synthesis routes were employed for the ZnO nanoparticles' preparation. The blue emission originates from the zinc interstitial (Zn i ) and oxygen interstitial (O i ) defects, which indicate that the mechanochemical route resulted in more interstitial defects compared to oxygen substitution (O Zn ) and oxygen vacancy (V o ) defects which otherwise would give green emission. Mn doping resulted in shifting of near-band-edge (NBE) emission and the reduction in the intensities of NBE, blue and green emissions. The initial red shift at lower Mn content could be due to s–d and p–d exchange interactions as well as band tailing effect where as the blue shift at higher Mn content can be attributed to the Burstein-Moss shift. The reduction in emission intensity could be due to non-radiative recombination processes promoted by Mn ions with increasing Mn content.

High strength AA2219 aluminum alloys have gathered wide acceptance in aeronautic and aerospace applications mainly due to their excellent mechanical properties, high corrosion resistance and good weldability. However, these alloys have poor as welded joint strength. The loss of strength is due to melting and quick resolidification, which renders all the strengthening precipitates to dissolve. One way of improving strength is through the modification of weld microstructures. The refinement of fusion zone microstructure helps in improving the mechanical properties of weld metal. The present study has investigated the influence of Tibor additions on the structure and mechanical properties of AA2219 gas tungsten arc (GTA) weldments. Full penetration GTA welds were prepared using alternating current (AC). It was observed that grain size was decreased with increasing amounts of Tibor. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness.

The present study has investigated the influence of scandium additions on the structure and mechanical properties of AA2219 gas tungsten arc (GTA) weldments. Controlled amounts of scandium modified AA2319 fillers were introduced into the molten pool of AA2219 by predeposited cast inserts under different welding conditions in GTA welding. Full penetration GTA welds were prepared using alternating current. It was observed that grain size decreased with increasing amounts of scandium and gradual transformation from columnar to equiaxed grain morphology. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, strength, and ductility. Room temperature hardness and tensile properties at different temperatures (room temperature, 100, 150, 200 and 250 °C) of weldments in the as-welded condition were observed and correlated with microstructure. The results show that the welds subjected to post-weld aging treatment have displayed superior hardness and tensile strength.

Synthetic Hydroxyapatite (HA, Ca10(PO4)6(OH)2) have the ability to provide the appropriate, scaffold or template for bone formation because of similar chemical and crystallographic structures to bone. The addition of 10wt. % of Ti powder in nano-HA powder was done by using ball milling. The different sintering temperatures at 1000, 1050, 1100, 1150 and 1200°C of nano-HA-Ti pallet were studied. Nano-HA-Ti pallet after vary sintering temperature were tested by hardness and compression strength tests. The optimum sintering temperature to sintered nano-Ha-Ti was at 1200°C because it gave the highest hardness and compression values which were 290.80HV and 78.49MPa. From Scanning Electron Microscopy (SEM) analyzed, nano-HA-Ti particles at 1200°C showed the attachment of nano-HA powder with Ti powder at grain boundary and some crack had form.

SnO2 is an n-type semiconductor with rutile crystalline structure and display many interesting optical properties. However, there are limited reports on effect of Mn doped SnO2 on optical properties, prepared by mechanochemical processing. This paper reports the effect of Mn doping on structural and optical properties of SnO2 nanoparticles (Sn1-xMnxO2, x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) prepared by mechanochemical processing in a high energy ball mill and heat-treated at 600 °C. Phase analysis of the dried powders was carried out from the data obtained by X-ray Diffraction (XRD) of the samples. The peak shifting in XRD patterns indicate that Mn ions were successfully doped into the SnO2 crystal lattice with successive increase in dopant levels. Average crystallite size, was calculated based on Scherrer's equation, and was found to vary from 24 to 35 nm. Blue shift in Eg at x>0.02 may be affected by decrease in crystallite size. Red shift in Eg with increasing Mn concentration (x ≤ 0.02) could be attributed to either sp-d exchange interaction and to the increasing crystallite size of the SnO2 nanoparticles. The quantum confinement effect was suggested to be the dominant reason for the changes in Eg. The reduction in emission intensity could be due to non-radiative recombination processes promoted by Mn ions with increasing Mn content.

The application of nanomaterials has gained considerable momentum in various fields in recent years due to their high reactivity, excellent surface properties and quantum effects in the nanometer range. The properties of zinc oxide (ZnO) vary with its crystallite size or particle size and often nanocrystalline ZnO is seen to exhibit superior physical and chemical properties due to their higher surface area and modified electronic structure. ZnO nanoparticles are reported to exhibit strong bacterial inhibiting activity and silver (Ag) has been extensively used for its antimicrobial properties since ages. In this study, Ag doped ZnO nanoparticles were synthesized by mechanochemical processing in a high energy ball mill and investigated for antimicrobial activity. The nanocrystalline nature of zinc oxide was established by X-ray diffraction (XRD) studies. It is seen from the XRD data obtained from the samples, that crystallite size of the zinc oxide nanoparticles is seen to decrease with increasing Ag addition. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) data also supported the nanoparticle formation during the synthesis. The doped nanoparticles were subjected to antimicrobial investigation and found that both increase in Ag content and decrease in particle size contributed significantly towards antimicrobial efficiency. It was also observed that Ag doped ZnO nanoparticles possess enhanced antimicrobial potential than that of virgin ZnO against the studied microorganisms of Escherichia coli and Staphylococcus aureus.

La 0.85− x Sm x Ag 0.15 MnO 3 ( x =0−0.2) ceramics were prepared using the conventional solid-state synthesis method to investigate the effect of Sm 3+ substitution on magnetic and electrical transport properties. Magnetic susceptibility versus temperature measurements showed all samples exhibit ferromagnetic to paramagnetic transition with Curie temperature, T c decreasing from 283 K ( x =0) to 164 K ( x =0.2) with increasing Sm 3+ . The observed slope in susceptibility, χ ′ versus temperature curves below T c indicates the possible presence of FM and AFM phases in the metallic region. In addition, a deviation from the Curie–Weiss law above T c in 1/ χ ′ versus T curves indicates the existence of a Griffith's phase in the x =0.05−0.2 samples due to the Sm 3+ ion substitution. The Griffith temperature, T G was found to decrease from 295 K ( x =0.05) to 229 K ( x =0.2). Electrical resistivity measurements of the samples in zero field showed transition from metallic behavior to insulating behavior as the temperature was increased. For x =0, two metal–insulator, MI transition peaks were observed at T p 1 =282 K and at T p 2 =250 K. Both peaks shifted to lower temperatures with the increase in Sm 3+ . The relative resistivity of the first peak to the second peak decreases with increasing Sm 3+ for x >0.05 while at x =0.2 the T p 1 peak was strongly suppressed. Magnetoresistance, MR was observed to weaken with Sm 3+ substitution. The metallic region of the ρ ( T ) curve of the x =0−0.15 samples was fitted to the model of electron–electron and electron–magnon scattering while the insulating region was fitted to the variable range hopping, VRH model. The resistivity behavior indicated that the substitution of Sm 3+ weakened the double exchange process and enhanced the Jahn–Teller effect. Our results indicated that the T p 1 peak is strongly related to the double-exchange mechanism while the T p 2 peak is suggested to originate from magnetic inhomogeneity.