Search

A combination of ultrahigh resolution mass spectrometry (MS), MS/MS fragmentation, nuclear magnetic resonance spectroscopy (NMR), and computational chemistry was used to probe the reaction mechanis...

Magnesium aluminate spinel with an initial MgO: Al2O3 molar ratio of 2:1 was prepared from its constituent oxides through a solid-state sintering process at temperatures ranging from 1550 to 1700 °C in a normal air atmosphere. The effect of varying amount (0.25–1.0 wt%) of TiO2 and Yb2O3 on densification, phase assemblage, mechanical, thermo-mechanical properties and microstructure of magnesia-rich spinel were investigated under static heating condition. The addition of TiO2 and Yb2O3 favours the densification of magnesia-rich spinel, which is discernible up to 1650 °C. This beneficial effect may be attributed to the development of the secondary phase and formation of solid solution due to the dissolution of the additive ions in the spinel structure. A marginal increase in the average grain size of the samples along with a narrower grain size distribution occurred with the incorporation of both the additives. Both the additives improved the mechanical properties of the magnesia-rich spinel; however, better room temperature flexural strength was achieved with Yb2O3 as compared to TiO2 addition. For the samples sintered at 1550 °C, 1.0 wt% Yb2O3 addition resulted in 30% increase in flexural strength; however, same amount of TiO2 addition increased the strength by 20%. In case of thermal shock resistance, 1.0 wt% TiO2 and 0.25 wt% Yb2O3 addition demonstrated promising result among all the samples.

A newly designed composition of non-equiatomic Fe40Cr25Ni15Al15Co5 medium-entropy alloy (MEA) was produced by induction melting (IM). The as-cast alloy was found to consist of a two-phase microstructure of BCC (2.87 ± 0.01 A) and ordered B2 (2.88 ± 0.02 A) type phases. The structures of these phases were confirmed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. It was observed that the Ni-Al-enriched ordered B2 phase of cuboidal shapes (~ 100 to 200 nm) is homogeneously distributed in Fe-Cr-rich BCC matrix with a cube-on-cube orientation relationship. The formation of the columnar dendrites (width 50 to 100 μm) was identified through optical microscopy (OM). The structural and microstructural stability of the alloy was investigated by heat-treating the alloy through different schedules. Heat-treated samples at different temperatures (< 1273 K) exhibit a similar type of two-phase microstructure with columnar dendrites. However, compositional rearrangement takes place during long time exposure to develop polymorphically related phases. The alloy was observed to possess a high compressive yield strength and hardness, i.e., ~ 1047 MPa and 391 ± 9 HV, respectively, at room temperature. Heat-treated samples at 600 °C and 900 °C (873 K and 1173 K) showed an increase in yield strength and ultimate strength with a significant increase in plasticity due to the increase in volume fraction of B2 phase and softening of the BCC matrix phase. The thermal stability and high strength of this alloy may open new avenues for high-temperature applications.

Galvannealed (hot dip galvanized and annealed) dual phase (DP600) steel and interstitial free (IF) steel are two of the widely used materials in automotive industries owing to their high specific strength, toughness, formability and corrosion resistance. This inevitably requires their joining to form larger components. Resistance spot welding has emerged as the predominant welding technique for joining of sheet metals in automotive industries. There are complexities regarding microstructural variation of the fusion zone and across heat affected zones during spot welding of fundamentally dissimilar steels. This is further aggravated by the prospect of zinc redistribution during the welding process. Current study presents the evolution of microstructure in different zones of welding in IF and DP600 steel. Micro-hardness profiles and electron back scattered diffraction studies were performed. Furthermore, redistribution of elements in different welding zones is studied using electron probe micro analysis. The effect of welding current and time on the nugget size and the strength of the weld during tensile–shear is determined. It was observed that there was an increase in nugget diameter and maximum load bearing capacity of the joint with an increase in heat input, until the occurrence of expulsion. Furthermore, critical nugget diameter for pull-out failure was determined and existing empirical models were verified for the applicability in this case. None of the existing empirical models could predict the critical nugget diameter correctly and thus a new empirical relationship between sheet thickness and critical nugget diameter for zinc coated dissimilar steels has been proposed. Failure behaviour of the spot-welded sheets were studied under tensile–shear configuration under quasi-static and fatigue mode of loading and it showed substantial difference in location of crack initiation and fractographic features. Tensile–shear specimen at optimum welding parameter failed from the base metal of the IF steel side with dimples on the fracture surface, whereas fatigue specimen failed from the heat affected zone of the IF steel side with transgranular striations on the fracture surface.

Two-dimensional lattices are ideal candidate for developing artificially engineered materials and structures across different length-scales, leading to unprecedented multi-functional mechanical properties which can not be achieved in naturally occurring materials and systems. Characterization of effective elastic properties of these lattices is essential for their adoption as structural elements of various devices and systems. An enormous amount of research has been conducted on different geometry of lattices to identify and characterize various parameters which affect the elastic properties. However, till date we can not control the elastic properties actively for a lattice microstructure, meaning that the elastic properties of such lattices are not truly programmable. All the parameters that control the effective elastic properties are passive in nature. After manufacturing the lattice structure with a certain set of geometric or material-based parameters, there is no room to modulate the properties further. In this article, we propose a hybrid lattice micro-structure by integrating piezo-electric materials with the members of the lattice for active voltage-dependent modulation of elastic properties. A bottom-up multi-physics based analytical framework leading to closed-form formulae is derived for hexagonal lattices to demonstrate the concept of active lattices. It is noticed that the Young’s moduli are voltage-dependent, while the shear modulus and the Poisson’s ratios are not functions of the applied voltage. Thus, the compound mechanics of deformation induced by external mechanical stresses and electric field lead to an active control over the Young’s moduli as a function of voltage. Interestingly, it turns out that a programmable state-transition of the Young’s moduli from positive to negative values with a wide range can be achieved in such hybrid lattices. The physics-based analytical framework for active modulation of voltage-dependent elastic properties on the basis of operational demands provide the necessary physical insights and confidence for potential practical exploitation of the proposed concept in various futuristic multi-functional structural systems and devices across different length-scales.

Fifteen-millimeter-thick aluminum alloy AA6082-T651 extruded flats were friction-stir-welded by using three different types of tool pin profiles, i.e., (1) conical with only left-hand threads (CL), (2) conical with both left-hand and right-hand threads (CLR), and (3) conical cam-tri-flute with left-hand threads (CTFL) up to a height of 6 mm from the pin tip. The microstructures and the mechanical properties across the weld thickness were characterized. Tunneling defect was found at the weld-bottom for the CL tool pin profile and at the weld-top for the CLR pin profile. The reasons behind the formation of such defects have been analyzed and discussed. On the other hand, a defect-free joint was obtained with the CTFL pin profile. Tensile test samples were machined from top, middle, and bottom sections of the welds, and tensile strengths were measured for all the sections to determine the joint efficiencies. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were employed to identify and study the morphology of the coarse phase particles present in the base material and in different regions of the welds. These results were correlated with the microhardness contours plotted across the weld cross section.

Here we report for the very first time the intelligent, novel design and synthesis, microstructural, optical as well as nanomechanical characterization of a multilayer ceramic polymer microcomposite (MLCPMC) structure comprising of a spin coated PEDOT:PSSlayer sandwiched between two spin coated TiO2 layers. The results show that in comparison to the nanomechanical properties of the polymeric PEDOT:PSS layer, spectacular improvement in nanomechanical properties is achieved in the MLCPMC structure. In addition, excellent optical tunability is achieved in the MLCPMC structures, without compromising the transmittance in the visible range. Thus, the novel MLCPMC structure may provide a further step towards materials for flexible electronics with additional benefit of extraordinary mechanical integrity. These results are discussed in terms of low temperature phase and microstructure development. Further, the mechanism of spectacular improvement in nanomechanical properties is proposed. Finally, the implications of these unique results for development of intelligently designed multilayered micro/nano composite structures for multifunctional applications in various domains such as strategic, space, military, structural, bio-sensing, OLED devices, DSSCs, flexible electronics and bioelectronic applications; are discussed.

The ceramic nanocomposites (CNCs) like zirconia toughened alumina (ZTA) ceramics are important futuristic materials for structural and functional applications in advanced strategic systems, structural components, biomedical prostheses and devices. In all structural materials including the ZTA CNCs, the very early stages of plastic deformation i.e., the incipient plasticity events (IPE) are most important to be understood so that the microstructure and mechanical properties can be tuned to suit a given end application. Here we report for the first time the mechanisms of IPE in the nanoindentation experiments conducted at 10–1000 mN loads in the 40 ZTA CNCs. Here 40 ZTA CNC stands for 40 vol% of 3 mol% Yttria partially stabilized zirconia toughened alumina (40ZTA) CNC. The role of load ranges in variations of the IPE related parameters in the 40 ZTA CNCs is also studied. Further, an attempt is made to assess how the amount of zirconia content in ZTA CNCs affects the variations of the IPE related parameters. Through the extensive usage of field emission scanning electron microscopy (FESEM) and theoretical estimations, efforts are also directed to check out the linkage, if any, between the localized shear deformation and/or microcracking with the IPE events that occur in the present CNCs. In addition, a new concept of damage resistance is introduced for the first time in the present work to explain the presence of a strong indentation size effect (ISE) in the 40 ZTA CNCs. Finally, an attempt is also directed to understand how the indentation load (P) controls the relative size of interaction zones of dislocation loops as well as the damage resistance and thereby, engineer the acuteness of the ISE in ZTA CNCs. The implication of these findings in futuristic design of especially the ZTA CNCs for various applications is also discussed.

Nanocrystalline Ba0·6Sr0·4Co0·8Fe0·2O3 (BSCF-6482) powder is synthesized by combustion synthesis technique. Powder calcined at 1000 °C reveals phase pure cubic perovskite. Transmission electron microscopic (TEM) analysis exhibits soft agglomerates of average size ∼50 nm wherein interplanar spacing for (110) and (221) resembles to the cubic lattice. While DC electrical conductivity of 23 S cm−1@800 °C is observed, interfacial polarization measured by electrochemical impedance spectroscopy is found to be the least @850 °C (0.18 Ω cm2). Cell performance has been compared among BSCF-6482, BSCF-5582 and LSCF-6482 mixed ionic and electronic conducting (MIEC) and conventional electrode (LSM). Higher performance (1.37 A/cm2@1.3 V,800 °C) with high hydrogen generation rate (0.57 Nl/cm2/h) is found during steam electrolysis with cell fabricated using BSCF-6482 having minimal area specific resistance 0.33 Ω cm2. Under similar operating condition, BSCF-5582, LSCF-6482 and LSM exhibit hydrogen generation rate of 0.35, 0.28 and 0.23 Nl/cm2/h respectively. Cell microstructure is clinically correlated with the higher reactivity of BSCF-6482 air electrode in steam electrolysis.

In this work, we have studied the effect of open air annealing on photo-induced microactuation (PIMA) property of a Co–Ni–Al melt-spun FSMA ribbon sample. This is one of the alloy systems that demonstrate the special type of PIMA effect while interacting with laser. This property has opened up the scope of various laser-controlled micromechanical engineering applications. Due to this importance, a detailed study has been made to explore the applicability of this alloy in different environmental conditions, where temperature plays an important role. The correlation between microstructure and the photo-induced microactuation (PIMA) properties has also been addressed here. The variation in actuation of the alloy with different heat-treated conditions has been studied in details. Transmission electron microscopy (TEM) was used to characterize the evolved microstructure for both the as-spun and the heat-treated alloy samples. The correlation between the evolution of the structural effects and resulting degradation of the PIMA property changes was also followed systematically to understand the correlation.

In the recent time, aqueous polymer quenchants are gaining importance in the steel heat treatment processes over conventional quenchants. It has been observed that desirable microstructure and mechanical properties can be achieved by proper adjustment of the quench parameters in the polymeric media. Reduction of distortion and cracking of heat treated steel has also been reported. However, the effect of this comparatively new technique of heat treatment on the tribologicalbehavior of steel has not been reported to a greater extent. In the present experimental study the effect of aqueous PEG-400 (poly ethylene glycol) solution as a quenching medium on medium carbon steel has been studied followed by the study of friction and wear. Multi tribotester ‘TR-25’ (DUCOM) has been utilized for this purpose. This paper also highlights the different applications of the new generation polymer quenchants and various critical quenching system parameters that need to be considered during the design stage of the quenching system for the new generation polymer quenchants. The results have been discussed along with necessary figures

The low carbon steel (LCS) rods were plastically deformed at room temperature up to a very high strain level by equal channel angular pressing (ECAP). ECAPed samples were further cryo-rolled at subzero temperature up to 94% area reduction. After plastic deformation, samples were annealed for short period at 475–675 °C temperature range. Optical microscopy and transmission electron microscopy are used to characterize primary microstructure and fine microstructural details respectively. Hardness of the deformed and annealed samples is measured by Vickers hardness testing. Results show that the grains are refined from 65 µm to 200 nm by ECAP at equivalent strain of 16.8, further grains are refined to

The development of high-temperature heavy-duty turbine disk materials is critical for improving the overall efficiency of combined cycle power plants. An alloy development strategy to this end involves superalloys strengthened by ‘compact’ γ′-γ″ coprecipitates. Compact morphology of coprecipitates consists of a cuboidal γ′ precipitate such that γ″ discs coat its six {001} faces. The present work is an attempt to investigate the microstructure and creep behavior of a fully aged alloy exhibiting compact coprecipitates. We conducted heat treatments, detailed microstructural characterization, and creep testing at 1200 °F (649 °C) on an IN718-variant alloy. Our results indicate that aged IN718-27 samples exhibit a relatively uniform distribution of compact coprecipitates, irrespective of the cooling rate. However, the alloy ruptured at low strains during creep tests at 1200 °F (649 °C). At 100 ksi (689 MPa) load, the alloy fails around 0.1% strain, and 75 ksi (517 MPa) loading causes rupture at 0.3% strain. We also report extensive intergranular failure in all the tested samples, which is attributed to cracking along grain boundary precipitates. The results suggest that while the compact coprecipitates are indeed thermally stable during thermomechanical processing, the microstructure of the alloy needs to be optimized for better creep strength and rupture life.

The influence of mechanical milling (MM), primarily on microstructure and phase evolution in Al62.5Cu25Fe12.5 (at%) quasicrystalline (IQC) matrix reinforced with varying volume fraction of Sn has been investigated by means of X-ray diffraction (XRD), scanning & transmission electron microscopy (SEM and TEM) and differential scanning calorimetry (DSC) methods. It was observed that with increasing the milling duration, the IQC phase transforms to crystalline B2 phase [Al (Cu, Fe) and Pm3 m, a = 0.29 nm]. In SEM and TEM analysis, it was found that both IQC and Sn particles are refined during MM. The XRD and TEM results confirm the formation nanostructured matrix consisting of nanocrystalline B2 phase along with minor IQC phase reinforced with ultrafine grained Sn particles after 40 h of MM. The STEM-EDS results show a homogenous distribution of elements (Al, Cu, Fe). The Sn particles were immiscible in a matrix consisting of B2 and IQC phase as indicated by XRD and TEM investigations.

Role of three rare earth oxides, viz., La2O3, CeO2 and Yb2O3 on reaction sintering of magnesium aluminate spinel having molar ratio of MgO:Al2O3 = 1:2 from its solid oxide precursors was investigated in static and dynamic heating conditions. Effect of these additives (3 wt%) on densification behavior, phase assemblage and microstructure development were studied in the temperatures of 1500–1700 °C. Yb2O3 enhanced the sintering of spinel, while La2O3 and CeO2 negatively impacted the sintering of magnesium aluminate spinel which can be discerned from the shrinkage curve of TMA as well as from static firing regime. This is ascribed to the formation of secondary phases in La2O3 and CeO2 containing samples which have different crystalline structures to that of spinel. This anisotropy due to different crystallinity hindered the pore shrinkage and pore removal and thereby retarded the densification. Whereas, the cubic structure of the secondary phase formed in Yb2O3 containing sample which is isotropic with the crystalline orientation of the parental spinel phase assisted the densification.

Developments of microstructures and texture are investigated for a low-carbon steel deformed by equal-channel angular pressing (ECAP) at room temperature for equivalent strain (evm) of 16.8. ECAP at evm = 0.6 reduces grain size by two orders of magnitude. With increasing strain, grain size reduces further and high-angle grain boundary (HAGB) fraction improves by grain subdivision and its change in orientation. ECAP of low-carbon steel up to evm = 16.8 can produce ultrafine grains of 0.2 µm size with HAGB fraction of 82%. The as-received steel has low texture index. Microstructural changes strongly influence texture development. It increases with equivalent strain as grain subdivision continues. Texture index fluctuates at intermediate strain range due to randomization of initial texture. Texture index reaches saturation at the high equivalent strain. On ECAP at low to intermediate strain evm = 0.6-6, components of both α (Fθ, Jθ, and $$ \overline{J} $$ θ) and γ (D1θ, D2θ, and Eθ) fibers are developed though all of them deviate from their ideal positions. At higher strain (evm = 9-16.8), the γ fiber components (D1θ, D2θ, Eθ) are strengthened, and the Eθ component reaches the highest intensity of ≈ 17 at evm = 12. There is no texture symmetry at low to high strain level. The presence of pearlite in low-carbon steel enhances strongly the deviation of texture components from their ideal positions in Euler’s space as well as it increases the intensities of the components more than that of IF steel for a similar equivalent strain.

Ti activated 72Ag-28Cu filler alloy was reinforced with micro/nano-Al2O3 ceramic particles for active brazing of synthetic diamond grits with 1045 steel. Microstructural changes due to reinforcement and corresponding influence on abrasion resistance characteristics of the modified filler alloy were observed. Different weight percentages (wt%), each of micro and nano-Al2O3 reinforcements, were tried. Micro-Al2O3 ceramic reinforcements were found to be uniformly distributed in the microstructure of the modified filler material. Alumina particles reacted with titanium to form hard Cu3Ti3O and TiO reaction compounds. Nano-Al2O3 reinforcements showed a tendency to get clustered, impairing the improvement in abrasion resistance property of the primary filler alloy. 1 wt% micro-Al2O3 added filler alloy underwent 58% less volumetric wear than the primary Ag-Cu-Ti alloy during the pin-on-disc test. This micro- reinforced filler also could effectively braze diamond grits with the steel without any significant deterioration in its wetting ability on diamond surface and joint strength, compared to its counterpart having the primary formulation.

The present study reports the evolution of microstructure and magnetic properties of Cu2MnAl1-xGax Heusler alloys. The L21 phase, which remained stable up to a Ga substitution of x=0.3, transformed into mixed phases, i.e., hexagonal close packed (HCP) and complex cubic structure (CCS) on further addition of Ga. The non-monotonic increase in the lattice constant indicates that some amount of Ga retains its monovalent state. The magnetic phase showed a transition from ferromagnetic to paramagnetic state with increasing Ga concentration. The re-entrant temperature (TR) decreased from 8.2 K to 5.2 K as Ga content increased from 5 at% to 10 at%. The strength of magnetic exchange-coupling also reduced with an increase in Ga content. Gaussian process regression (GPR) was used to estimate the lattice parameter using the ionic radii and Pauling electronegativity of the constituents. The modeling approach showed high accuracy and stability, providing new insights into future alloy development.

The high temperature strength of directionally solidified Ni-base super alloy CM 247LC strongly depends on the morphology, volume fraction, size and size distribution of γ′ precipitate (Ni3Al) in the FCC γ matrix. The microstructure of the alloy is engineered to achieve the right combination of these parameters that provides the required high temperature strength and creep resistance. The alloy contains high volume fraction of coherent γ′ precipitates having near cubic shape. High temperature exposure of gas turbine components made out of the alloy leads to coarsening of the γ′ precipitates and broadening of the γ matrix channel. This in turn, adversely affects the high temperature mechanical properties of the alloy. The present study endeavours to non-destructively characterize such detrimental changes in the microstructure that controls the mechanical properties and limits the life of components. The microstructural changes of the fully heat treated alloy exposed at 980 °C for different hours (100–1200) of thermal exposure have been characterized using ultrasonic methods. Changes in microstructural parameters due to different hours of thermal exposure have been correlated with changes in ultrasonic velocity, ultrasonic attenuation coefficient and second order acoustic nonlinearity parameter. It is observed that the change in attenuation is predominantly by absorption of the ultrasonic wave due to dislocation damping in the γ channels. Nonlinear ultrasonic parameter changes with thermal exposure predominantly due to the alteration of dislocation precipitate interaction. A dislocation precipitation interaction model for ultrasonic wave distortion has been used to explain the observed variation in nonlinear parameter. A microstructural parameter has been identified that varies in a similar way as ultrasonic attenuation and second order ultrasonic parameter. It is shown that variations in the acoustic non-linearity parameter follow the trend more closely with the identified microstructural parameter.

Methylene blue (MB) dye present in industrial wastewater is a well-known carcinogenic source. By utilizing phase pure three dimensional self assembly of magnesium hydroxide nanoparticle (3DSAMHNPs)...

This study investigated microstructure evolution, thermo-magnetic and mechanical behavior of magnetic shape memory thin film at different substrate temperature. X-ray diffraction measurements reveal the evolution of different phase structure concerning substrate temperature. According to microstructure analysis, the grain size increases with the substrate temperature and also the shape of the grain changed from pyramidal to spherical. A strong dependence of magnetic properties on grain size and phase structure is also observed. Coercivity is found to decrease with increasing substrate temperature up to a minimum value of 62 Oe for the film deposited at 773 K and with further increase in substrate temperature it is found to increase. Based on the relationship between grain size and the nanoindentation results, the decline in the hardness and elastic moduli can be reasonably inferred to be associated with enlarged grain size, consistent with the “Hall–Petch” effect and the grain refinement mechanism.

Here we report for the very first time the synthesis of 100% phase pure calcium silicate nanoparticles (CSNPs) of the α-wollastonite phase without using any surfactant or peptizer at the lowest ever reported calcination temperature of 850 °C. Further, the phase purity is confirmed by quantitative phase analysis. The nano-network like microstructure of the CSNPs is characterized by FTIR, Raman, XRD, FESEM, TEM, TGA, DSC etc. techniques to derive the structure property correlations. The performance efficacies of the CSNPs against gram-positive e.g., S. pyogenes and S. aureus (NCIM2127) and gram-negative e.g., E. coli (NCIM2065) bacterial strains are studied. The biocompatibility of the CSNPs is established by using the conventional mouse embryonic osteoblast cell line (MC3T3). In addition, the biofilm inhibition efficacies of two varieties of CSNPs e.g., CSNPs(W) and CSNPs(WC) are investigated. Further, the interconnection between ROS e.g., superoxide (O2.-) and hydroxyl radical (.OH) generation capabilities of CSNPs and their biofilm inhibition efficacies is clearly established for the very first time. Finally, the mechanical responses of the CSNPs at the microstructural length scale are investigated by nanoindentation. The results confirm that the α-wollastonite phases present in CSNPs(W) and CSNPs(WC) possess extraordinarily high nanohardness and Young's moduli values. Therefore, these materials are well suited for orthopaedic and endodontic applications.

The feasibility of significant weight reduction in conjunction with the superior strength-ductility combination makes Fe-Mn-Al-C-based steels the candidate material for automotive and structural applications. The alloy chemistry and processing conditions influence the microstructure in low-density steels (LDS); however, their role in deformation behaviour is not fully understood. In the present study, three different austenitic LDS grades viz. Fe-28Mn-9Al-0.9C, Fe-28Mn-9Al-5Ni-0.9C and Fe-15Mn-9Al-5Ni-0.9C alloys in hot-rolled conditions were used for evaluating the role of secondary phases, especially B2 ordered Fe(Ni)Al phase on deformation characteristics. Ni-free LDS microstructure consisted of the γ-matrix with fine κ-carbides, whereas Ni containing low Mn alloy possessed coarser κ-carbides along with B2 in both bamboo-like stringer and polygonal particle morphology in the γ-matrix. The B2 containing alloy exhibited higher strength with reduced tensile ductility than the B2-free alloy. Hardness of the γ-matrix and B2 phase were similar with B2 grains exhibiting distinct pop-in events in the nanoindentation curves indicating incipient plasticity. The γ-matrix and B2 co-deform near yield, and a favourable orientation relationship (OR) between the γ-matrix and B2 facilitated easy slip transfer, while the non-favourable OR controlled ductility by strain accumulation and B2-cracking. The differences in the strain hardening behaviour of B2-free and B2 containing alloys were elucidated based on the changes in dislocation substructure evolution examined by an automated crystal orientation mapping in electron microscopy.

Nanocrystalline MIEC air electrodes, viz., La-Sr-Co-Fe and Ba-Sr-Co-Fe (6482) and nano-Gd-doped ceria (GDC) are synthesized using solution combustion technique and hydroxide co-precipitated route, respectively. Synthesized calcined nanopowders are characterized for phase purity using X-ray diffraction showing rhombohedral lattice for LSCF and cubic lattices for BSCF and GDC. Detailed transmission electron microscopy (TEM) reveals a near-net shape nanoparticles of MIEC perovskites and agglomerate free nanoparticles for GDC, and thus a composite functional layer was formulated in combination with MIEC and GDC to adhere in between electrolyte/interlayer and electrodes. Lower electrode polarizations of 0.017 Ω.cm2 and 0.17 Ω.cm2 with high exchange current density prove better electrode kinetic phenomena @850 ℃ for both LSCF-6482 and BSCF-6482 with sufficiently high current densities for both SOFC and SOEC modes of operation with the highest hydrogen generation rate of 0.62 Nl.cm−2.h−1. Cell performances are clinically correlated with the cell microstructure.

The aim of this investigation is to study precipitation behavior in an aluminum alloy AA2618, based on Al–Cu–Mg–Si–Ni–Fe system. The as-received extruded alloy was solution treated and independently aged at ambient temperature as well as aged for various times at 193 ± 1 ℃, and at 275 ± 1 ℃ for 5 h. TEM revealed that the microstructure developed due to prolonged natural aging consisted of a fine distribution of Guinier–Preston–Bagaryatski (G-P-B) zones. During artificial aging, the sample aged for as low as 1 h revealed the presence of very fine precipitates on both {220}Al and {420}Al planes. With increasing artificial aging hours, widespread precipitation occurred on both {220}Al planes, and, of course, on {420}Al planes that are known to be due to the S′/S (Al2CuMg) phase. The corresponding selected area diffraction patterns confirmed the presence of G-P-B zones and S phase in the microstructure. Preliminary high-resolution transmission electron microscopy (HRTEM) did confirm the presence of precipitates on {220}Al planes in the artificially aged samples of AA2618.

Consolidation of powder inside Additive Friction Stir (AFS) tool poses a problem of hindering its application. Additive Friction Stir Processing (AFSP) is a simple modification of this technique which can negate this. A slightly modified version of this AFSP is used in the present work to successfully make a 3D deposit structure of height 5 mm and width 64 mm. Microstructural study was done both in longitudinal and transverse directions. Induced isotropy was predicted from similar microstructures in these directions. No layer effect was seen in a particular deposit layer, unlike layered Friction Stir Welding. Also, the microstructure was similar in the deposit along the build-in direction. Reduction in the number of voids that was observed in the deposit might help to increase its hardness and other mechanical properties.

Gallium having low surface energy (∼ 600 mJ/m2) and low melting temperature (29.76 °C), was utilized to substitute Al in Al-Pd-Mn quasicrystalline alloys, which may be considered for future development of a quaternary QC alloy with low surface energy. The influence of Ga up to 5 at% in decagonal Al70-XGaXPd10Mn20 (x = 0, 2.5, 5.0) alloys on the stability of decagonal phase was investigated systematically. The surface morphology and phase stability were studied in as-cast (slow cooling from liquid) and also in annealed condition (i.e., annealing at temperature 800 °C for 24 h). It is observed that Ga influences the stability of decagonal phase and the evolution of microstructure. The phase transformation from the mixed icosahedral and decagonal quasicrystal phases coexisting in as-cast Al70-XGaXPd10Mn20 (x = 0, 2.5, 5.0) alloys to a single decagonal quasicrystalline phase was observed on annealing, implying relative phase stability of quaternary decagonal phase around these compositions.

The microstructural, mechanical, and shrinkage characteristics of cement mortar containing 100% fine reclaimed asphalt pavement (RAP-mortar) were revealed through an extensive experimental ...

A high-throughput approach for collecting microstructure and mechanical properties were developed to model the process–structure–property (PSP) correlations in polycrystalline Ni-based superalloy ME3. The semi-automated image processing algorithm captured the area fraction and size distribution of secondary and tertiary γ′ particles from scanning electron microscopy (SEM) images of polished samples. The yield strength and elastic modulus were calculated with an automated algorithm using load-time-displacement data generated by microindentation. Thirty heat treatments were conducted to create various γ′ distributions which are the primary strengthening mechanism of Ni-based superalloys. The PSP correlations among the predictor and response variables were evaluated with regression models and validated with adj-R2 and residual standard error statistics. The PSP statistical models built by using high-throughput protocols align with the previous statistical and theoretical models.

The present work aims to investigate the mechanical and microstructural properties of dissimilar welding of 2014-T6 and 7075-T6 aluminium alloys of 6 mm thick sheets, using butt welded friction stir welding. The two distinct materials welded with the perpendicular to the rolling direction of the dissimilar weld zone. The welded joint was tested in tension at room temperature to investigate the mechanical response and also to observe the differences with the parent materials. The diversity in the properties across the weld and its material mixing behavior have considered by resolving the thermal cycle, hardness test, and microstructural analysis. Plastic deformation along with recrystallization during the welding process resulted in the formation of distinct zones which could be identified by their respective microstructures. SEM/EDS analysis was carried out to analysis the precipitates, which influenced the properties of the joints. Based on the present study, 840 rpm with 30 mm/min weld speed seemed to be optimum.