Search

This work is to optimize the back pressure (BP) and processing temperature required for equal channel angular pressing (ECAP) of commercially pure magnesium. ECAP was performed at different processing temperatures with different back pressures for one pass. For a combination of back pressure and processing temperature the crack-free samples were obtained. Microstructural characterization of pure magnesium samples after ECAP was performed using an optical microscope and mechanical behavior is discussed with hardness and tensile test results. From the XRD peak profiles, the microstructural feature such as crystallite size, micro-strain and dislocation density are analyzed using the modified Williamson and Hall (W-H) method. The results concluded that the processing temperature of 200 °C and back pressure of 150 MPa is the best combination of processing parameters to process crack-free pure magnesium by ECAP.

In-spite of many advantages of Al-Si alloys, it is limited in industrial application due to lack of ductility, because microstructure contains plate like Si particles which is embedded in an Al-matrix. This article describes the modification effect on microstructure and mechanical properties of sodium modified hypoeutectic Al-Si alloys. Modification has been done by using pure Na as modifier with different composition 0.08, 0.12 and 0.16 wt% at 10, 15 and 20 min holding time on hypoeutectic Al-Si alloy. Microstructure of modified samples has been analyzed by optical microscope and eutectic particle size was measured by using ImageJ software. In all cases the modified microstructure has shown the fine fibrous eutectic particle which is uniformly distributed throughout the sample. Tensile and hardness test were carried out by tensometer and Vickers hardness testing machine and the properties were studied. The fracture surface analysis was carried out by SEM. Due to modification, eutectic particle size has reduced and mechanical properties have improved.

The effect of weave pattern on the mechanical properties of basalt- reinforced epoxy composite was investigated. Basalt in the plain and twill weave fabric forms were used for reinforcement, and lapox (L-12) epoxy resin was used as the matrix. Different weave types and their effect on mechanical properties of the weave were considered in the present study. The composite laminate was fabricated by the compression molding technique. Mechanical tests including tensile, compressive, and hardness tests were conducted as per the ASTM standards. Plain weave composites exhibited better mechanical properties compared with twill weave composites. From the results, it was evident that the weave pattern of the fabric significantly influences the strength of fibre reinforced composites.

This study aims at studying the dynamic mechanical and thermogravimetric properties of boron carbide (B4C) filled carbon fiber (CF)/epoxy composites (BC-CF/Ep composites) using the wet lay-up process assisted by vacuum bagging technique. The B4C fillers were used in varying filler weight percentages (1%, 3% and 5%) in the different CF/Ep composites and are uniformly mixed in epoxy system through ultrasonification process and was used as the matrix. The Toray make bidirectional twill (2 × 2) woven T800CF was used as the reinforcing material. The Dynamic Mechanical Analyzer (DMA) and Thermogravimetric Analysis (TGA) tests are conducted to study the dynamic capacity and thermal degradation behavior respectively. In the DMA, the storage modulus (E1), loss modulus (E11), damping behavior (Tanδ) and glass transition temperature (Tg) of CF/Ep composite specimens are studied with increasing temperature from (25–173)°C. The BC1% composites showed better storage modulus, loss modulus and damping factor, while unfilled CF/Ep and BC3% composites showed better Tg than other CF/Ep composites. As far as TGA is concerned, the BC1% composites exhibited better thermal stability than all other composites. The dynamic tests resulted in the trend of BC1% > unfilled CF/Ep > BC3% > BC5% composites. The TGA tests also followed the trend of BC1% > unfilled CF/Ep > BC3% > BC5% CF/Ep composites.

This research focuses on the static mechanical, thermal and tribological properties of carbon fibre epoxy (CF/Ep) composites filled with boron nitride (BN) micro-filler powder (BN-CF/Ep). The mechanical properties studied were tensile, flexural, interlaminar shear strength and hardness. The thermal properties studied were dynamic mechanical and thermogravimetric analyses which were analysed through dynamic mechanical analyser and thermogravimetric analyser, respectively. The curing ability and dispersion of BN filler in the Ep and composites were investigated through differential scanning calorimetry, Fourier-transform infrared spectra and scanning electron microscopy. The tribological properties focused were three-body abrasion and dry sliding friction and wear conduct. Three-body abrasion tests were studied with silica sand of 212 µm particle size, 30 N load, 2.38 m s−1 sliding velocity and variable abrasive distances of 250 m, 500 m, 750 m and 1000 m. The dry sliding wear tests were performed using pin-on-disc (POD) wear experimental set-up with 60 N load, 3 m s−1 sliding velocity and variable sliding distances of 1000 m, 2000 m and 3000 m. The results followed the trend of BN1% > BN3% > BN5% composites in all mechanical properties. The carbon fabric reinforcement along with the BN-Ep matrix improved enormously all the mechanical properties except impact resistance. Further, it was exhibited that 1 wt% BN into CF/Ep prompts better mechanical properties with predominant damping capacity and thermal stability. Both the dry sand abrasive wear and POD test outcomes revealed that all BN-CF/Ep composites prompt predominant wear resistance. CF along with BN improves enormously the wear resistance with friction coefficient. Further, it was exhibited that 1 wt% BN into CF/Ep in both three-body abrasive and POD tests prompts better wear resistance. Generally speaking, it was presumed that BN-CF/Ep gracefully and successfully improved the mechanical, thermal and tribological properties and morphology of Ep for various mechanical, electrical components and load-bearing applications used in automotive and engineered applications.

The role of metal matrix composites (MMC) has gained huge momentum in the various research as well in the industrial application due to its high stiffness and high strength to weight ratio. It helps in achieving enormous weight reduction without compromise in the strength of the material. In this study, a novel attempt is made to fabricate MMC with martensitic stainless steel as matrix and titanium diboride (TiB2) as reinforcement. The AISI 420 matrix with different weight percentage (0%, 1%, 2%, and 4%) of TiB2 reinforcement was fabricated by vacuum induction melting technique. The fabricated composite was subjected to X-ray diffraction (XRD) study which revealed the presence of TiB2 phase as well as its respective crystal structure. The microstructural characterization of the AISI 420/TiB2 composite was done. Optical microstructure reveals the presence of secondary phase reinforcement in a homogeneous manner inside the matrix and also across the grain boundaries. Scanning electron microscopy (SEM) images further ensure the availability of TiB2 in the matrix. The hexagonal morphology in the SEM ascertains the TiB2 presence. Energy dispersive spectroscopy (EDS) spectrum shows the presence of the T and B elements in the appropriate weight and atomic percentages. Microhardness results of the composite show that the hardness value increases with the more addition in the wt% of TiB2 particles. The overall results confirm that the AISI 420 metal matrix composite with TiB2 reinforcement can be effectively synthesized by casting route. The addition of TiB2 enhances the hardness of the composite significantly

The present article deals with reinforced AA7075 CuCNT/CuGrP Hybrid nano Composite. To find the corrosion resistance of such an alloy composites, was made by compo casting (Stir- Squeeze) are commonly used for the production of components, such as cylinders, pistons, pumps, valves and combustion chambers, which in service may experience a corrosion phenomenon. Initially different percentage of microstructure, hardness, and mechanical properties were measured. Corrosion tests were carried out according to different mass fraction of copper coated CNTs and copper coated GrP was added to the AA7075 casting and the composition is optimised. The electrochemical corrosion behaviour of CuGrP and CuCNT reinforced AA7075 were studied using Electrochemical Polarization Technique (ACM Gill) and Electrochemical Impedance Spectroscopy Technique. The phase analysis of the composites were done by XRD, microstructure by optical microscope even severity of corrosion is measured optical microscope. The corrosion behaviour of the composites and the possible mechanism for the effect of CuCNT and CuGrP in the properties have been studied in detail in this paper.

The present work compares the numerical fluid dynamic and wall erosion characteristics of a single phase fluid flowing through two vertical pipe bend assemblies: sharp (S) and mitred (M). Both the ‘S’ and ‘M’ pipe bend assemblies have circular section with double bends each having a 90° flow turning angle. The ‘S’ bends has a single weld joint and the ‘M’ bends were made of 2 pieces of miter segments, thus having three weld joints. Single phase fluid (water) was made to flow at five Reynolds numbers 1e5

The aim of this paper is to investigate the mechanical properties of Nickel Aluminium Bronze (NAB) alloying with Niobium (Nb) and Yttrium (Y) rare earth metals. NAB alloy frequently used in the aqueous solution as well as less widely used deployed materials were studied. To avoid failures due to aqueous environment. Niobium (Nb) and Yttrium as chosen alloying addition with NAB. The Nb and Y rare earth element which acts as stabilizing element to existing NAB system to optimize the mechanical properties. The NAB with alloying elements processed in the vacuum induction furnace by means of predetermined parameters. After casting, the samples were tested for the mechanical properties like tensile and Brinell hardness to ensure improvements with the master NAB system. At the same time, the characterization techniques SEM and EDAX with mapping analysis confirmed the chemical proportions of the elements in the developed NAB with proposed NAB (Nb) and NAB (Y) alloys. A comparative study is to be made for the NAB with Nb and Y under aqueous environment based for the developed alloys.

Rare earth oxide reinforced Aluminium matrix composite are produced using La2O3 as dispersoids in VAL12 aluminium alloy matrix by varying the percentage of dispersoids. The composites are tested for their microstructural evolution and mechanical properties. Advanced characterization techniques are used in characterizing the composites to reveal the microstructural and physical properties. The microscopic examination reveals refinement in grain structure with increasing reinforcement percentage of La2O3. XRD results shows peak broadening of matrix and increase in the intensity of dispersoids peak confirming the presence of reinforcement in the matrix. Energy dispersive spectrum mapping further confirms the elemental composition of the composites. The actual density of the composites are more than 95% of the theoretical density as the squeeze casting process produces with very less porosity level. The tensile test results show loss of ductility in the composites having dispersoids more than 4% (by wt.) which was further elucidated with the fractographic and machining studies. Fractographic results show fracture propagating in both matrix and reinforcement as there is good interface between matrix and reinforcement. The machining studies on developed composites reveal continuous, semi continuous and disintegrated chips, revealing increase in brittle nature with respect to increase in dispersoids percentage.

The influence of crystalline nature of aluminium in mechanical properties of carbon Nanotubes (CNT) reinforced Aluminium alloy is reported. The materials chosen for this study is AA 4032 alloy powders and multi-walled Carbon Nanotubes (MWNT). Three different composites were prepared by powder metallurgy technique. First is an AA4032/MWNT microcrystalline composite, second one is AA4032/MWNT nano-crystalline composites and third one is AA4032/MWNT bimodal composites. The microcrystalline structure was prepared by regular P/M route where nano-crystalline and bimodal structure was prepared by mechanical alloying. The micro-hardness and compressive strength of different composites were measure and analyzed.

Cast hyper duplex stainless steel (HDSS) was modified with a stabilizer Niobium to suppress the formation of deleterious intermetallic phases. Based on the Thermo calc, samples were heat treated at 900 °C and 1150 °C. Intergranular corrosion resistance was studied with the help of double loop electrochemical potentiokinetic reactivation (DL-EPR) method. Surface of the specimen was characterized by optical microscope, SEM coupled with EDS. Addition of niobium retards the formation of chromium carbides and the same was confirmed with EDS point analysis. DL-EPR shows the better degree of sensitization for niobium stabilized cast HDSS than the regular HDSS.

The conventional copper alloys with regular grain structure and size are relatively low yield soft materials. To overcome this limitations of conventional tin bronze monolithic material to achieve good combination of strength, along with stiffness, toughness and density, current work focuses on the development of composites using boron carbide particulates as reinforcement. Boron carbide was chosen as a particle reinforcement for composite material for its high hardness, high melting point, low density, with high elastic modulus (448 GPa) and chemical properties. The composites are tested for its mechanical properties and correlated with the microstructural morphological changes using advanced microscopic techniques. The tensile test results shows on increasing percentage of reinforcement, the ductility of the composites is lost. The composites show, microstructural refinement and formation of intermetallic phases, at the grain boundaries justifying increases in the hardness and tensile strength of the as cast composite.

Rare earth oxide reinforced Aluminium matrix composite are produced using La2O3 as dispersoids in VAL12 aluminium alloy matrix by varying the percentage of dispersoids. The composites are tested for their microstructural evolution and mechanical properties. Advanced characterization techniques are used in characterizing the composites to reveal the microstructural and physical properties. The microscopic examination reveals refinement in grain structure with increasing reinforcement percentage of La2O3. XRD results shows peak broadening of matrix and increase in the intensity of dispersoids peak confirming the presence of reinforcement in the matrix. Energy dispersive spectrum mapping further confirms the elemental composition of the composites. The actual density of the composites are more than 95% of the theoretical density as the squeeze casting process produces with very less porosity level. The tensile test results show loss of ductility in the composites having dispersoids more than 4% (by wt.) which was further elucidated with the fractographic and machining studies. Fractographic results show fracture propagating in both matrix and reinforcement as there is good interface between matrix and reinforcement. The machining studies on developed composites reveal continuous, semi continuous and disintegrated chips, revealing increase in brittle nature with respect to increase in dispersoids percentage

An investigation has been performed on the slurry erosion behavior of squeeze cast AA7150 aluminium alloy – a potential structural alloy in as cast condition. The tests were conducted at room temperature varying the service factors using quarts silica sand. The cast samples were examined for its metallurgical and mechanical factors followed by investigation on erosive wear behavior. The results showed the ductile nature of mechanism undergone and greater influence was seen with respect to the angle of impingement. The erodent flow rate also significantly affects the performance of the material. The surface morphologies of the wear tested specimens were examined using SEM for better understanding on the mechanism of failure. Severe plastic deformation is seen in all the cases as the strain energy exceeded the elastic strain rate.

This article reviews the current state of the art in understanding manganese steels. The standard manganese steel (Hadfield’s Manganese) has roughly 12% manganese and 1.2% carbon. This approximate 10 to 1 ratio from Hadfield’s work. Then there is High manganese steels with 18–31% Mn with higher carbon content upto 1.9%, higher manganese grades require elevated carbon levels in order to achieve the desired increase in service life. And other being Lean manganese steels with 5–8% Mn, 1%C and 1.5%Mo to help stabilize the austenite. Medium Mn steels had been investigated due to their excellent balance between material cost and mechanical properties. Consisting of a single α′ martensite phase in hot and cold rolled states and multiphases after inter-critical annealing. The steels exhibit high strength and good ductility due to transformation induced plasticity occurring in retained γ γR, whose volume fraction is approximately 0.2–0.4. There another deformation mechanism called twinning induced plasticity (TWIP) enhances certain Manganese steels. TWIP steels exhibit very high strain hardening rate due to the deformation twins taking advantages of dynamic Hall-Petch effect. In TWIP steels the manganese content varies between 20 and 30%. In spite of some very desirable properties, it also poses a challenge in materials production. Reducing Mn content in TWIP steels and addition of Al reduced the tendency for delayed cracking. Since the Mn content in TWIP steels influences the stacking fault energy (SFE) which plays major role deformation mechanism. This review concludes by suggesting fundamental research needs to promote the design of manganese steels with improved properties and performance.

SS321 is used as the electrolyte reservoir to store potassium hydroxide electrolyte. The metal is prone to get corroded at the electrolyte environment. The present work is carried out for minimizing the corrosion of SS321 potassium hydroxide electrolyte reservoir which is a part of the AgO-Zn reserve primary battery by passivation with citric acid. The uniqueness of the present work exhibits the optimization of passivation method and process conditions, to withstand concentrated alkaline (KOH) medium stored in SS321 electrolyte reservoir, which is having a long life of more than 7 years. Polarization and KOH resistance tests suggest that AISI 321 showed excellent passivation studies behavior when treated with citric acid solution. Hence it is necessary to establish the corrosion behavior of SS321 electrolyte storage container in alkaline solution by electrochemical studies. The thickness loss and weight loss are the main parameters measured to quantify the amount of corrosion. The Voltammetry and AFM studies established the minimum corrosion rate by passivation process method. Based on the results of electrochemical studies and anodic polarization experiments, it was confirmed that the passivation layer formed by treating the material with Citric acid, is capable of improving the corrosion resistance of stainless steel significantly and the passive film is more stable than those produced by other passivating methods. Thus, to minimize the rate of corrosion on electrolyte storage container for the period of battery life of more than 7 years, citric acid passivation having a good corrosion resistance in concentrated alkaline electrolyte (KOH) medium, is best suited and the method of treatment involved is benign & environment friendly.

The main aim of this study was to get a better knowledge of mechanical properties of carbon fabric reinforced epoxy (CF/Ep) composites. The selected mechanical properties of the CF/Ep composite with different fiber architectures (T300CF/Ep, T700CF/Ep and T800CF/Ep) are investigated for indentation, in-plane, tensile and bending loads. All composites were fabricated with equal weight percentage of carbon fiber and similar consolidation process using hand layup procedure followed by compression moulding method. Experimental results showed that the effect of fiber weave structure on mechanical properties of the CF/Ep composites is more obvious than that in neat epoxy. Both tensile and flexural results showed that high strength carbon fiber (T800) has evident strengthening effects on the tensile and bending load response of CF/Ep composites. The fiber architecture marginally affects the density and severely affects strength and deformation of composites. T300CF/Ep and T800CF/Ep composites are nearly linear up to final brittle fracture while T700CF/Ep system exhibit non-linearity before failure. Furthermore, it is seen that composite performance is dictated by inherent properties of carbon fiber and weaves structure. Even with fiber flaws, stress concentrations, the weaving pattern is beneficial because it makes composites to be very less subtle to flaws. These characteristics are addressed systematically with consideration of numerical aspects of fibers strength and critical defects formation. The significant developments in the mechanical properties of composite systems are further assisted using scanning electron microscopy

The basic property of corten steel is its ability to create a protective layer on its surface in unfavorable environments. This protective layer protects the steel without an anti-corrosion coating. But owing to water accumulation in passenger coaches near lavatory areas and different climatic conditions especially in high chloride conditions, the protective layer formation is not possible leading to premature failure due to accelerated corrosion. In this work, the corrosion resistance of polyurea coatings compared with present coating was studied on corten steel. The coated steel is subjected to immersion and salt spray test and the corrosion rate are evaluated based on ASTM B117 Standards. The corrosion resistance of coating was assessed by monitoring the polarization resistance of the coated steel immersed in 3.5% wt of NaCl solution. The profilometry of the samples were also done to elucidate the enhancement of corrosion resistance of coated steel.

This research work based on carbon fiber epoxy (CF/Ep) composites shows the effect of Boron carbide B4C filler on mechanical properties using a hand layup procedure followed by the vacuum bagging process method. The boron carbide fillers were uniformly dispersed in epoxy resin and used as matrix material. The weight percentage of (B4C) filler material in the composite was varied and mechanical properties were obtained with microfiller. The T800CF/Ep composites with 1%wt., 3%wt. and 5%wt. B4C fillers were taken for evaluating the mechanical properties. All composites were fabricated with an equal weight percentage of carbon fiber and a similar consolidation process. The mechanical properties like tensile properties, flexural properties, Interlaminar shear strength, impact strength and hardness are studied to know how the mechanical response of composite structures varies with filler addition. Testing followed the trend of 1%wt. > 3%wt. > 5%wt. of B4C in all mechanical properties of B4C filled CF/Ep composites. Tensile strength of 1%wt. B4C filled composites were better than basic CF/Ep composites whereas 3%wt. & 5%wt. B4C filled composite values were lower. The tensile modulus of all the B4C filled composites was better than basic CF/Ep composites. Flexural properties of 1%wt. and 3%wt. B4C filled composites were better than basic CF/Ep composites whereas 5%wt. B4C filled composite values were lower. Interlaminar shear strength (ILSS) of 1%wt. B4C composites gave better results whereas 3%wt. and 5%wt. B4C filled composites gave lower results. The impact energy of all composites gave lower values than basic CF/Ep composites. Hardness values of all B4C filled composites were better than basic CF/Ep composites. The most important developments in the mechanical properties of composites are further supported by scanning electron microscopy.

Air receivers in railway coaches usually come under severe degradation due to exposure to external atmosphere and corresponding climatic changes. IS 2062 Steel is used for this application. Frequent cleaning and replacement become part of the process. Polymer based coating can save this material from corrosion and subsequent wear. In this work poly urea coating was carried out on an IS 2062 steel. The corrosion properties of the coating were studied using potentiodynamic polarization test in ASTM standard 3.5%NaCl solution. The corrosion resistance of coated material was compared with the base material. The depth of corrosion of the samples were studied to evaluate the enhancement of corrosion resistance of coated IS206. The poly urea coating enhances codal life of these material by manifold.

This research paper based on bidirectional carbon fiber/epoxy composites (CF/Ep) shows the effect of fiber architecture on mechanical properties using a hand layup procedure followed by the vacuum bagging process method. The three different fiber architectures T800CF/Ep, T700CF/Ep and T300CF/Ep were chosen for studying the mechanical properties. All composites were fabricated with an equal weight percentage of carbon fiber and a similar consolidation process. The tensile properties, flexural properties, interlaminar shear strength, impact strength and hardness are studied to know how the mechanical response of composite varies with fiber architecture. Testing results showed that the effect of fiber weave architecture is more obvious in CF/Ep composites than in neat epoxy with regard to mechanical properties. Both tensile and flexural properties showed that T800CF/Ep composites have a very good strengthening effect on both tensile load response and bending load response of CF/Ep composites. The fiber architecture has less effect on the density and serious effect on the strength and deformation of CF/Ep composites. Inherent properties and weaves structure of carbon fiber (CF) dictated the performance of composites. Compared to Hand layup method, the Vacuum bagging method showed (2–6)%, (11–15)%, (5–6)%, (15–20)% and (1–3)% improvement in tensile strength, tensile/flexural modulus, ILSS, impact strength and hardness respectively whereas the flexural strength values were almost near to the former values Grunenfelder et al. (2017). The most important developments in the mechanical properties are further assisted by scanning electron microscopy.

An investigation was carried in Nickel Aluminium Bronze (NAB) alloyed with Niobium (Nb) and Yttrium (Y) to study the effect of the microstructure for onshore applications. Nickel Aluminium Bronze is broadly used in aqueous atmospheres due to their good mechanical and corrosion resistance properties. The presence of destructive species in aqueous water initiates the corrosion of the engineering modules is inevitable. In-order to optimize the corrosion resistance Nb and Y were added as (1%, 2% & 3%) respectively in the master NAB. The specimens were exposed to the immersion test in NaCl solution. To create the behavior of corrosion and succeeding erosion, altered immersions hours were selected as 8, 16, 24, 32, 40, 48 and 54 h. The mass loss measurements were obtained after the completion of the individual specified time to calculate corrosion rates (CR). Solid particle erosion (SPE) investigations were also carried out on the developed alloys. The size of the particle which is used in the investigation is 50 µm. Corrosion rate was calculated and it is correlated with the immersion time. Scanning electron microscopy (SEM) investigations were observed for the corroded and eroded specimens.

The present work compares the flow characteristics of a single phase fluid flowing through two vertical pipe bend assemblies: sharp (S) and mitred (M), using CFD. Both the ‘S’ and ‘M’ pipe bend assemblies have circular section with double bends each having a 90° flow turning angle. The ‘S’ bends has a single weld joint and the ‘M’ bends were made of 2 pieces of miter segments, thus having three weld joints. Water was made to flow at five Reynolds numbers 1e5

Metallic corrosion is a major concern for bogie side frames used in railways. The exposure to harsh environment is unavoidable and a protective coating is one possible solution. In this work, tungsten-based carbide coating was produced on EN10025/5 steel. The corrosion properties of the coating were studied using potentio dynamic polarization test using actual field conditions and using ASTM standard 3.5% NaCl. The coating was subjected to slurry exposure using waterjet erosion tester. The microstructure of the eroded area was studied for understanding the wear mechanism. The corrosion and erosion of the coating was compared with the base material. It was evident that tungsten-based carbide coating increases the corrosion and erosion resistance of steel in railway application.

Duplex stainless steels (DSS) exhibit excellent corrosion resistance and mechanical properties to the severe environments and hence are used in many engineering applications such as oil and marine industries, chemical storage, nuclear power plants, and many more. These are used as valves, fittings, and pipes to suck the crude oil in oil fields. Austenite (γ) and ferrite (δ) phases constitute the microstructure of DSS. However, one needs to control both the phases towards making it lucrative in desired applications. Investigations on tribological behavior of cast DSS are limited. The current work focuses on optimizing the wear parameters for slurry jet erosion and analyzing their effect on wear of the 5A DSS. Grey relation analysis (GRA) and Taguchi design of experiments have been used for optimization. Slurry jet erosion tester was used investigate the response of the material to various designed experiments. Worn-out surfaces morphologies and wear mechanisms were revealed using Scanning electron microscopy (SEM), whereas white light interferometer was used to understand 3D morphologies the surfaces.

La2Ti2O7 nano metric powder was prepared using solid state route and evaluated in the present study. Precursors of lanthanum oxide and titanium dioxide were blended, synthesized at 850 °C for 8 h. The phase analysis of the synthesized powder was carried out using XRD diffraction analysis to check the purity of the perovskite La2Ti2O7 compound formed. The crystalline size measurement was carried out using Debye–Scherrer formula which reveals that the synthesized powder at 850 °C for 8 h is in the range of 49.54 nm. The powder morphology was studied using the SEM and EDS result confirms the presence of La, Ti and O elements. The SEM results reveal irregular morphology of the powders and few clusters which may be attributed to the presence of the moisture in them.

Nanocrystalline powders of 4 mol.% GdO1.5-4 mol.% SmO1.5 doped ZrO2 (4Gd4SmSZ) has been synthesized by co-precipitation process. Their phase transformation and crystalline growth behavior was investigated by Thermo gravimetric-Differential Thermal Analysis (TG-DTA), X-ray Diffraction (XRD), Raman spectroscopy and High-Resolution Transmission Electron Microscopy (HR-TEM) after calcinations at different temperatures. The XRD, Raman spectra and HRTEM results confirm the nature of tetragonal zirconia (t-ZrO2). The prepared 4Gd4SmSZ powders, remains in the single metastable tetragonal phase over the whole calcination temperature ranging from 873 K to 1273 K for 2 h. The crystallite size varies from 11.98 nm to 18.90 nm with increase of temperature from 873 K to 1273 K. The activation energy of the prepared powders at low temperature is considerably lesser than that at a higher temperature. The annealed 4Gd4SmSZ powders had shown excellent phase stability at 1573 K for 100 h. Keywords: Zirconia, Coprecipitation, Rare earth oxide, Phase transformation, Tetragonal, Activation energy

Mg-9Li-3Al magnesium alloys with varied level of Nd added (i.e., 0-2.0wt. %) alloys were prepared electric resistance stir casting furnace under controlled inert gas atmosphere. Impact of Nd addition on metallographical changes and mechanical characteristics of as-cast alloys were analyzed by using an OM, XRD, SEM with EDS. The metallography evaluation revealed that adding Nd refines the microstructures due to formation of Al2Nd and Al11Nd3 precipitates, these precipitates exists together with α-Mg, β-Li, AlLi, MgLi2Al phases in the alloy. Furthermore, adding Nd improves the mechanical strength and elongation. 1.5wt.% Nd added alloy displayed the better mechanical characteristics; UTS is 166MPa; Elongation 16.87%.

The effect of cerium addition on AZ91 magnesium alloy and its influence on stress corrosion cracking (SCC) were studied using constant load proof ring testing NaCl-K2CrO4 and ASTM D1384 solutions at 70 and 80% of yield stress, respectively. The investigation revealed that the optimum grain refinement of desired phases occurred with 0.5% addition of cerium. The addition levels of cerium above 1.5 wt.% to AZ91 alloy resulted in premature failures due to poor SCC resistance in both solutions (K2CrO4 and ASTM D1384 solutions). The microstructural studies of the experimental alloys were characterized by using optical and scanning electron microscopy. The elemental compositions of cerium-added AZ91 magnesium alloys were studied by energy-dispersive spectroscopy. The results indicate that the mode of SCC failure was found to be transgranular in nature along with secondary cracks containing cleavages which resulted from the hydrogen embrittlement and anodic dissolution phenomena. The AZ91 alloy with 0.5 wt.% cerium exhibits better mechanical properties and high stress corrosion resistance.

As-cast Mg-9Li-3Al-xNd (x = 0-2.0 wt.%, with the variation of 0.5wt.%) magnesium alloys were prepared through casting in electrical induction melting furnace under a controlled inert gas atmosphere. Influences of Nd over the metallography changes and corrosion characteristics of Mg-9Li-3Al alloys have been examined by following techniques are OM, XRD, SEM and potentio-dynamic polarization (PDP) test. The results illustrate that adding Nd modifies the continuous β-Li phases into discontinuous phase by the formation of new precipitates such as Al2Nd and Al11Nd3. Meanwhile, the grain sizes of Mg-9Li-3Al-xNd alloys reduced with respect to the increasing Nd content. PDP results disclose that the Nd addition reduces the corrosion current density (icorr) of Mg-9Li-3Al alloys which can be essentially produced by grain refinemente.

In this work multi-component equiatomic and non-equiatomic AlCoCrCuFeTix hexanary high-entropy alloys (HEA) was synthesised through mechanical alloying. The prepared powder was sintered via spark p...

In this research, friction stir processing (FSP) was used to produce three different surface composites of AA5083 reinforced with B4C, SiC, and TiC particles. The effects of reinforced particles and three consecutive FSP passes on particle distribution, microstructure, mechanical and wear properties were studied. The microstructure reveals significant grain refinement with a dense distribution of particulates towards the retreating side and advancing side of stir zone, some region at the centre of stir zone shows particle free bands and excellent bonding between particle and matrix. FSP induces severe plastic deformation promoting mixing and refining the constituent phase in the materials. Mechanical properties and wear resistance of the FSPed samples were evaluated and compared with the matrix alloy. The results show that the incorporation of B4C, SiC and TiC particles into the matrix improves the hardness, tensile and wear properties. TiC and SiC particulates reinforced surface composites reveals a ductile mode of fracture whereas B4C reinforced surface composite shows a bimodal type of fracture. The investigation on wear mechanism was performed using a pin-on-disc tribometer. The results show that the wear mode changes from abrasive to delamination wear.

This research aims to characterize the bead geometry, metallurgical aspects of the optimized maraging steel (250 grade) weld track processed by autogenous gas tungsten arc welding technique. Design of experiments was used to determine the weld track possessing optimal bead geometry. Welding speed and current were the parameters considered for optimization. Depth of penetration and bead width were the adjudicating parameters for optimality. Taguchi analysis showed that welding current is directly proportional to depth and width whereas weld speed was indirectly proportional. Statistical analysis indicated that welding speed has affected the depth of penetration and different current levels have affected the width of the weld bead linearly. Optical microscopy and SEM/EDAX analysis were done to investigate the post weld microstructural changes. X-Ray Diffraction were done to understand the phase formations.

The bimodal structured composites of aluminum – carbon nanotubes prepared using powder metallurgy technique with coarse grained AA 4032 powders and nanocrystalline structured AA 4032 powders. Microstructural observations by optical microscope and transmission microscope ensure the complete densification and uniform distribution of carbon nanotubes. These bimodal composites exhibited high compressive yield strength with good ductility. The result shows improved mechanical properties of composites than alloy.

This research emphasizes the impact of Cerium oxide on grain size and corrosion behavior of AA2219 fabricated by the Squeeze casting technique. The composites were effectively characterized by electron backscatter diffraction EBSD, which indicates a significant reduction in grain size inherited by the thermo-physical properties of the dispersoids, which in turn enhances the mechanical properties. The Corrosion behavior of squeeze cast samples was examined through the potentiodynamic polarization technique with Tafel polarization using a standard solution of 3.5% NaCl. The microscopic characterization of the corroded regions reveals that the sample with higher reinforcement of 2% CeO2 is more resistant to the pitting attack due to the hydrophobic nature of the dispersoids.

Nanocrystalline samaria (8 mol%) doped zirconium oxide (8SmSZ) was synthesized using reverse co-precipitation technique, the calcination temperature ranging from 873 K to 1273 K for 2 h. XRD structural analysis results confirm the tetragonal(t) nature of the synthesized 8SmSZ nanocrystalline powder. The calculated crystallite size of tetragonal zirconia calcined at 873 K is around 9.0±0.5 nm and with increase in calcination temperature the size increases to 16.0±0.8 nm (1273 K). Thermogravimetric-Differential thermal analysis (TG-DTA) was carried out to study the crystallisation kinetics and growth behaviour of the 8SmSZ. The activation energy for the crystallisation of tetragonal ZrO2 formation in the 8SmSZ powder was found to be 308.1 kJ/mol by a non-isothermal DTA method. The growth morphology parameter was found to be n=2 indicating two-dimensional growth. The phase stability of the samples after annealing at 1573 K for 100 h was investigated by Raman spectroscopy and it was found that samaria doped zirconia exhibits better phase stability. These preliminary results confirmed the higher phase stability at elevated temperature thereby confirming its suitability in thermal barrier coating (TBC) applications.

Intergranular corrosion of duplex stainless steel is a major concern in high corrosive environments. Interstitial stabilization of alloy is a possible technique for susceptibility to intergranular corrosion. In this paper, zirconium addition was made to 5A grade cast duplex stainless steel in order to achieve the stabilization. Addition of zirconium forms a mixture of zirconium carbides and nitrides which suppress the chromium depletion and thus increase the intergranular corrosion resistance. The metallurgical characterization was carried out on the specimens by means of optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffractometry. Corrosion behavior investigation using oxalic acid etch test and double-loop electrochemical potentiokinetic reactivation technique results underline the superior corrosion-resistant property of zirconium-added cast duplex stainless steel.

Nanocrystalline powders of ZrO2–8mol%SmO1.5 (8SmSZ), ZrO2–8mol%GdO1.5 (8GdSZ), and ZrO2–8mol%YO1.5 (8YSZ) were prepared by a simple reverse-coprecipitation technique. Differential thermal analysis/thermogravimetry (DTA/TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM) were used to study the phase transformation and crystal growth behavior. The DTA results showed that the ZrO2 freeze-dried precipitates crystallized at 529, 465, and 467°C in the case of 8SmSZ, 8GdSZ, and 8YSZ, respectively. The XRD and Raman results confirmed the presence of tetragonal ZrO2 when the dried precipitates were calcined in the temperature range from 600 to 1000°C for 2 h. The crystallite size increased with increasing calcination temperature. The activation energies were calculated as 12.39, 12.45, and 16.59 kJ/mol for 8SmSZ, 8GdSZ, and 8YSZ respectively.

Mg–8Li–3Al+xCe alloys (x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg–8Li–3Al+xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B–117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg–8Li–3Al (LA83) alloy results in the formation of Al2Ce intermetallic phase, refines both the α-Mg phase and the Mg17Al12 intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.

Equi-atomic and non equi-atomic multi-component systems were synthesized through different routes to form high-entropy single solid solution. One such high-entropy alloy (HEA) with hexanary composition AlCoCrCuFeZn x was synthesized using mechanical alloying. The effect of zinc variation on the crystal structure and phase formation was characterized using XRD, FESEM with EDS and TEM. The synthesis resulted in both equi-atomic and non equi-atomic nano crystalline AlCoCrCuFeZn with a crystallite size less than 10 nm.

The corrosion behaviour of Mg–6Al–1Zn + XCe (where X = 0.5, 1.0, 1.5 and 2.0 wt% Ce) alloys, aged for 18 h at different temperatures of 180 °C, 200 °C, 220 °C and 240 °C, was studied in 3.5 wt% NaCl solution. The salt spray test was conducted in accordance with ASTM-B117 standard (fog test). The corrosion morphologies, corrosion rate and the composition of the corrosion products were investigated by X-ray Diffraction (XRD), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) techniques. The results show the cerium addition and ageing treatment has significantly influenced the corrosion morphologies and the corrosion rate. In AZ61 alloy, the intermetallic β (Mg17Al12) phase acts as a corrosion barrier and upon ageing the Al4Ce phase precipitates along the α grain boundaries. The precipitation modifies the β phase to form more continuous network which subsequently reduces the corrosion attack in the chlorine environment. Salt spray test result shows the AZ61 alloy with 1.5 wt% Ce aged at 220 °C exhibits the better corrosion resistance.