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The γ-FCC (face-centered cubic) to e-HCP (hexagonal close packed) phase transformation in a laser additively fabricated Co-29Cr-5Mo alloy was investigated. The microstructure of the as-built material was γ-FCC featured with a sub-micron scale dislocation cell structure and stacking faults. Aging at 1073 K led to rapid transformation within 0.5 h to the e-HCP structure in a massive mode, characterized by: (i) composition invariance, (ii) oriented grain face nucleation; and (iii) interface-controlled linear growth mechanism. Effective lowering of the carbon content in the γ-FCC by partial tie-up as carbides along prior grain and dislocation cell boundaries and the diverse grain structure and interfaces are believed to promote the massive transformation.

The aimed study proposes laser shock peening without a coating of high strength ultrafine bainitic steel to mitigating the fatigue failures for automotive and structural engineering applications. Laser pulse density of 2500 pulses/cm2 (75% overlapping) was optimised based on the induced residual stresses for employing the wide range of characterisations. The roughness and topographic results showed that surface roughening was controlled by tuning the laser pulse density. The High-Resolution X-ray Diffraction analysis confirmed the lattice misorientation resulting peak shift and the trend towards martensite phase transformations. The electron microscopic micro/nanostructure analyses revealed the grain refinement features such as nano-twins, micro shear bands and shear cells. The work hardening depth analysis indicates the significant enhancement in the mechanical properties. Completely reversed (R = −1) high-cycle fatigue tests extended the lifespan by an average of five times than the untreated. Also, it has potential to repair the structural components effectively.

The development of graded microstructure in Ni-base Alloy 602CA, processed through the new technique of high reduction (per pass) cold rolling (HRCR) and the severe surface plastic deformation technique of ultrasonic nanocrystal surface modification (UNSM) was investigated. Clear through-thickness gradients in residual stress, dislocation structure and boundary density with misorientation >2° were observed after the HRCR and UNSM. However, the gradient in HRCR did depend on the roll-pass schedule: relative reduction per pass, total reduction and direction of the roll pass. Applying maximum reduction per pass and minimum number of passes exhibited an improved graded microstructure for 40% total reduction in both unidirectional (UR) and cross rolling (CR) cases. The UR40 and CR40 in HRCR process led to graded microstructures that compared well with those produced by UNSM.

The enhanced nonlinear optical absorption and optical limiting properties of polymeric one dimensional photonic crystal (1DPhC) with ZnS nanoparticles as defect are reported. The 1DPhC was fabricated by spin coating technique, using polystyrene (PS) and cellulose acetate (CA) as high and low refractive index materials. ZnS nanoparticles were synthesized in CA solution by laser ablation technique and the structural, morphological and non linear optical characterizations were done. A microcavity structure with cavity resonance around 532 nm was designed by inserting ZnS NPs/CA defect layer between two Bragg reflectors comprising 10 bilayers of CA/PS. A significant enhancement (4.6 times) in both nonlinear absorption and optical limiting properties of 1DPhC with ZnS defect layer was observed under 532 nm pulse excitation compared to the ZnS reference sample. The enhancement in the observed nonlinear optical properties of the system could be accredited to the confinement of optical field due to the localization of photons in the cavity mode. The current system can play crucial roles in designing practical nonlinear optical devices, such as optical limiters, optical switchers etc.

The present work has important implications for the use of graphene as reinforcement and interlocking the grains in nanocomposites. In order to achieve this, low energy laser shock peening (LSP) assessed on graphene (0.4 wt %)-AA 7075 nanocomposites fabricated through powder metallurgy (PM) technique and hot extrusion (28:1 extrusion ratio). As a consequence, substantial improvement in microstructure observed for the nanocomposites up to 400 µm depth. The added graphene serves the pinning effect and blocks the grain growth in the nanocomposites. LSP contribute the additional grain refinement effectively along interlocking the grains by graphene called pinned dislocation core in the nanocomposites leading to large deformation texture strengthening. Addition of graphene found to have improved in the ultimate tensile strength (UTS) by 42.93%, LSP has contributed 10.66%.

The objective of this study is to understand the influence of surface treatments, namely laser shock peening (LSP) and ultrasonic nanocrystal surface modification (UNSM), on the irradiation tolerance of a Ni-base alloy. Surface treatments such as LSP and UNSM have been shown to mitigate the potential for primary water stress corrosion cracking (PWSCC). As such, there is emerging interest in the development and implementation of LSP and UNSM for nuclear reactor components. The LSP process utilizes a laser-generated plasma, while UNSM utilizes mechanical contact at ultrasonic vibration speeds, to create near-surface compressive residual stresses, high dislocation densities, twins and subgrains, and nanostructuring of the workpiece. These resultant microstructural changes can substantially affect the creation and evolution of irradiation damage. Herein, we study precipitation hardened Ni-base Alloy 718+, which is utilized in reactor components exposed to PWSCC-inciting environments. Specimens are treated with LSP or UNSM, then irradiated with 2.0 MeV protons to 7 displacements per atom (dpa) at 500°C. The dislocation line density is roughly an order of magnitude larger in the unirradiated LSP and UNSM specimens than in the baseline (untreated) specimen. Irradiation-induced dislocation loop nucleation results in an increase in the areal density of dislocation-type defects. Irradiation also induces disordering of the γ′ precipitates; this disordering appears more extensive in the baseline than in the LSP and UNSM specimens. Results are considered in the context of overall sink strength. Finally, irradiation-induced softening is observed in all specimens through nanoindentation, and is ascribed to the overall change in sink strength, resulting from the competition between γ′ disordering and dislocation loop nucleation.

Extrusion based high-throughput Additive Manufacturing (AM) provides a rapid and versatile approach for producing complex structures by using a variety of polymer materials. An underexplored aspect of this technique is concerned with the formation of interfaces between successively deposited layers. This is particularly important for large-scale additive manufacturing of semi-crystalline polymers because of the highly non-isothermal conditions involved, which influence both nucleation and crystal growth. The objective of this work is to investigate the microstructure and the corresponding viscoelastic properties of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) resulting from extrusion-based high-throughput AM process. Questions on development of morphology focus on polymer crystal structure and carbon fiber orientation in the vicinity of the interface between successive layers. This study attempts to establish a fundamental understanding of the role of the AM has in transferring a set of intrinsic material properties to the macroscopic properties of the final AM structure.

The nonlinear optical properties of phenothiazine-iodine (PTZ-I) charge transfer complexes (CTC) in three different proportions were investigated by z-scan set up using Nd: YAG laser at 532 nm wavelength, 7 ns pulse width and 10 Hz repetition rate as excitation source. The interaction between phenothiazine and iodine was analysed using FTIR spectroscopy. The morphological changes after the formation of CTC were observed with the help of scanning electron microscopy and optical microscopy. The CTC system displayed an absorption in the UV-Visible region, which is attributed to the charge transfer between constituents. Optical nonlinearity was observed to be maximum when the molar ratio between phenothiazine and iodine is 1:1, and it strongly depends on the electron donor-acceptor proportion. Optical limiting threshold values of the studied samples are comparable to many reported values. The excellent nonlinear optical properties exhibited by PTZ-I CTC make them promising candidates in nonlinear optical applications.

The combination of interlocked lamellae grains is the primary feature of biological material “nacre” to constitute its highest strength. The mimic of this hierarchical assembly of biological material combinations remains the challenge for the future trending bioinspired engineering materials. In this study, the interlocked nanolaminated architecture of graphene-reinforced aluminum alloy nanocomposite achieved via multi-step powder metallurgy route and industrial extrusion process followed by laser shock peening. Interrupted re-nucleation to obtain lamellae grains, controlled laminates sliding through interlock mechanism and inhibited large dislocation loop formation in the nanocomposites during laser shock peening was significantly influenced the mechanical properties of the nanocomposites. Consequently, enhancement in the hardness, tensile strength, wettability characteristic properties and prolonged fatigue life cycles were achieved significantly for nanocomposites.

Localized plastic deformation and hardening was studied in laser shock peened (LSP) Inconel 718 SPF (Super plastic forming), a fine grained Ni-Base superalloy, using electron backscatter diffraction (EBSD), nanoindentation, and micro pillar compression testing. 718SPF samples were LSP-treated with two different laser power densities. After LSP, the plastic deformation is manifested as increase in the fraction of low angle misorientations and the formation of sub-grain boundaries. EBSD was used to study plastic deformation as a function of distance from the peened surface for different laser intensities. Different approaches like image quality mapping and local misorientations analysis were used to study the in-depth distribution of the plastic strain. Results show that EBSD is effective in the qualitative characterization of localized plastic strain of the materials subjected to LSP.

In this study, we investigate the effect of thermo-mechanical processing (TMP) on the evolution of low coincident site lattice (CSL) grain boundaries (3 ≤ Σ ≤ 27) and thence on the precipitation behavior of carbides at various types of grain boundaries in Alloy 600. Detailed analysis of the microstructure using Electron Back-scattered Diffraction (EBSD) in the scanning electron microscope (SEM) as well as Precession Electron Diffraction (PED) and Energy Dispersive X-ray Spectroscopy (EDS) in the transmission electron microscope (TEM) has been used to study the effects of TMP on the precipitation of Cr carbides and Cr depletion. After TMP, the fraction of low-CSL grain boundaries is increased appreciably and the precipitation behavior of carbides is modified resulting in lower sensitization. The results showed that Σ3 boundaries were more resistant to carbide precipitation as compared with random high angle boundaries due to their lower surface free energy. Furthermore, the decrease in effective grain boundary energy of the microstructure after TMP resulted in lower Cr depletion and lower sensitization along grain boundaries.

In this study, Inconel 718 (IN718SPF) samples were treated with three surface modification techniques: laser shock peening (LSP), cavitation shotless peening (CSP) and ultrasonic nanocrystalline surface modification (UNSM). Subsequently, these samples were exposed to temperatures between 550 °C–650 °C for different time intervals. Residual stresses on the sample surfaces were measured using XRD to compare the thermal relaxation behavior of samples treated with different surface treatments. The results show that surface compressive residual stresses induced by all three surface treatments are stable at high temperatures after initial relaxation. Further, TEM micrographs were obtained from surface treated samples that were exposed to 550 °C for 5 min and 24 h. A comparison of microstructures before and after thermal exposure is presented. The study quantifies activation enthalpy for residual stresses relaxation in LSP, CSP and UNSM treated IN718SPF and a relaxation mechanism is proposed.

Ultrasonic Nanocrystal Surface Modification (UNSM) is a mechanical surface treatment that induces large compressive residual stresses and near-surface microstructural changes in the material by using repetitive impacts at ultrasonic frequencies with a WC tip. In this study, we investigate the use of UNSM to improve the fatigue life of ATI 718 Plus (718Plus) at high temperature of 650 °C. UNSM induced severe surface plastic deformation which led to nano-sized crystallites, twins, and high dislocation density in the near surface regions, coupled with an increase in surface hardness and high magnitude of compressive residual stresses. This change in the near-surface microstructure remained stable at elevated temperatures. In addition, UNSM retained ∼−680 MPa near-surface residual stress (56% of its initial residual stress) even after 140 h exposure to 650 °C. The retained near-surface residual stresses and the stable microstructure from the UNSM increased the yield strength by ∼11% (∼105 MPa) and endurance limit by ∼8% (∼70 MPa) in corresponding tests at 650 °C. This improvement in fatigue life was attributed to near-surface microstructure changes, material hardening and high compressive residual stress induced by UNSM. The estimated crack growth rates were ∼60% lower for UNSM-treated 718Plus as compared with untreated material. The thermal-mechanical residual stress relaxation indicates the effectiveness of UNSM in improving the fatigue life of 718Plus at 650 °C.

During recent years, researchers have given more attention towards the spillover effects between exchange rates and stock indices, but the literature in this area seems to be inadequate and the interactions between currencies and stock markets are still not clear. This entails more attention to the dynamics of spillover effects between exchange rates and stock indices. Especially, after the global economic crisis BRICS has emerged as an inevitable economic force by strengthening its economic, financial and political relationship. The important reason behind this is that the global investors are considering BRICS as the most favourable destination for portfolios diversification. Besides, the characteristics of stock markets, the investors’ behaviour and the economic policies of BRICS are different from that of developed and other emerging nations. The existing literatures on the interactions between stock and currency markets of BRICS are comparatively limited and there is hardly any research that studied the long-run spillovers between stock and currency markets in BRICS. Hence, this research study has tried to identify the long-run spillover effect of US dollar on major stock indices of BRICS nations by applying individual and Panel Generalized Method of Moments (GMM). The results indicate that the appreciation in the value of BRICS currencies against dollars has increased the value of the respective nation’s stock indices.

The problem considered: This multi-centric study analyzed data of COVID-19 patients and compared differences in symptomatology, management, and outcomes between vaccinated and vaccine-naive patients. Methods: All COVID-19 positive individuals treated as an in-or out-patient from the 1stMarch to 15th May 2021 in four selected study sites were considered for the study. Treatment details, symptoms, and clinical course were obtained from hospital records. Chi-square was used to test the association of socio-demographic and treatment variables with the vaccination status and binary logistic regression were used to obtain the odds ratio with a 95% confidence interval. Results: The analysis was of 1446 patients after exclusion of 156 with missing data of which males were 57.3% and females 42.7%. 346 were vaccinated; 189 received one dose and 157 both doses. Hospitalization was more in vaccinated (38.2% vs 27.4%); ICU admissions were less in vaccinated (3.5% vs 7.1%). More vaccinated were symptomatic (OR = 1.5); half less likely to be on non-invasive ventilation (OR = 0.5) while vaccine naive patients had 4.21 times the risk of death. Conclusion: Severe infection, duration of hospital stays, need for ventilation and death were significantly less among vaccinated when compared with vaccine naive patients.

Low energy laser shock peening without coating (LSPwC) was conducted on AISI 304 austenitic stainless steel specimens with varying pulse densities or overlapping. Highest magnitude of compressive residual stress (CRS) was achieved for an optimized pulse density of 2500 pulses/cm 2 (75% overlapping). The 2-D and 3-D topographical analysis were indicative of the fact that controlled roughening of the surface was achieved after the LSPwC process. After the LSPwC process, the hydrophilic unpeened surface was converted into the hydrophobic surface, thus decreasing the wettability characteristics of the surface. The X-ray diffraction (XRD) results reveal that there is a beginning of the martensite transformation and the rise in the intensity value of the peaks after LSPwC indicates the presence of compressive residual stresses induced in the specimen. The optical microscope and high-resolution transmission electron microscope results provided evidence of grain refinement and deformation induced refinement features such as multidirectional mechanical twinning, dislocations lines, micro shear cells and stacking faults in the near and sub-surface areas. The average hardness value of the LSPwC specimens was found to be increased by 28% more than the untreated specimen. The potentiodynamic polarization revealed that there was a considerable amount of increase in the pitting corrosion resistance after the LSPwC process, thus, supporting to extend the fatigue life of the specimen. The electrochemical impedance spectroscopic (EIS) analysis depicts that the LSPwC process supports the formation of the strong passivation layer in 3.5% NaCl solution.

Rubbery materials are widely used in industrial applications and are often exposed to cyclic stress and strain conditions while in service. To ensure safety and reliability, quantifying the effect of loads on the life of rubbery material is an important but challenging task, due to the combination of geometric/material nonlinearities and loading conditions for extended time durations. In this work, a novel simulation approach based on nonlinear space-time finite element method (FEM) is presented with a goal to capture fatigue failure in rubbery material subjected to cyclic loads. It is established by integrating the time discontinuous Galerkin (TDG) formulation with nonlinear material constitutive laws. A continuum damage mechanics (CDM) model is introduced to account for the damage evolution and model parameters for synthetic rubber are calibrated based on experiment. The nonlinear space-time FEM coupled with CDM constitutive model shows good agreement with the fracture and low cycle fatigue test of notched rubber sheet specimen.

Ultrasonic Nanocrystal Surface Modification (UNSM) is a mechanical surface treatment that induces large compressive residual stresses and near-surface microstructural changes in the material using repetitive impacts at ultrasonic frequencies with a WC tip. In this study, we investigate the use of UNSM to improve the fatigue life of ATI 718 Plus (718Plus). UNSM induced severe surface plastic deformation in 718Plus, which led to nano-sized crystallites, twins, and high dislocation density in the near surface regions, coupled with an increase in surface hardness by 2.3 GPa and high magnitude of compressive residual stresses. These changes increased the endurance limit by ~ 13% (~ 100 MPa) in room temperature fatigue tests. This improvement in fatigue life was attributed to near-surface microstructural changes, material hardening and high compressive residual stress induced by UNSM. The crack propagation rates were 66% lower for UNSM-treated 718Plus as compared with untreated material. The residual stress relaxation after cyclic loading indicates the effectiveness of UNSM in improving the fatigue life of 718Plus.

Water quality maintenance is crucial in strategizing control and pitching in measures to reduce water pollution and degradation of aquatic ecosystems. Periodic monitoring of water quality is an essential exercise that can help keep track of water bodies' hydrological information. This article presented a novel system that can make water quality monitoring more efficient to prevent ongoing pollution control trends. Here, we implemented a well-structured technique to collect the quality parameters, especially chemical indicators, and generate characteristic maps for each parameter about the particular water body under survey. The data collected were transferred to the cloud in real-time to keep track of the water body's quality and access real-time quality data of different chemical and biological indicators like pH, dissolved oxygen, total dissolved solvents, turbidity, etc. The parameters monitored through the prototype built are pH and Temperature. The proposed system solved major limitations of existing methods, thereby improving water quality monitoring efficiency and minimizing water pollution.

The near-surface microstructure in an Al-Zn-Mg-Cu (7075-T6) alloy after Laser Shock Peening without Coating (LSPwC) was characterized by advanced electron microscopy methods. A remarkable microstructure composed of a ~2 μm wide newly solidified matrix recast surface layer embedded with O-rich Al nanoparticles (NPs) with the close-packed orientation relationship (OR) as the surrounding Al matrix has been discovered, together with a nano-scale aluminum oxide layer formed on the outermost surface. The formation mechanism is associated with high-pressure surface ablation leading to melting, vaporization and shock-assisted rapid solidification during the LSPwC process. The close-packed OR between NPs and matrix is believed to be due to surface energy minimization.

Laser shock peening (LSP) of Al2O3 armour ceramics is reported for the first-time. A 10 J, 8 ns, pulsed Nd:YAG laser with a 532 nm wavelength was employed. The hardness, KIc, fracture morphology, topography, surface residual stresses and microstructures were investigated. The results showed an increase in the surface hardness by 10% which was confirmed by a reduction in Vickers indentations size by 5%. The respective flaw sizes of the Vickers indentations were also reduced (10.5%) and inherently increased the KIc (12%). Residual stress state by X-ray diffraction method showed an average stress of −64 MPa after LSP, whilst the untreated surface stress measured +219 MPa. Further verification with the fluorescence method revealed surface relaxation with a maximum compressive stress of −172 MPa induced after LSP within the Al2O3 armour ceramic. These findings are attributed to a microstructural refinement, grain size reduction and an induction of compressive stress that was relaxing the top/near surface layer (post LSP) from the pre-existing tensile stresses. Further process refinement/optimization will provide better control of the surface properties and will act as a strengthening technique to improve the performance of armour ceramics to stop bullets for a longer period of time and protect the end-users. Keywords: LSP, Ceramics, Al2O3, Hardness, KIc, fracture toughness, residual stress, Microstructure

Laser Shock Peening (LSP) is a mechanical surface treatment that induces large compressive residual stresses and microstructural changes in the material by using repetitive shocks from laser pulses. In this study, we investigate the use of LSP to improve the fatigue life of ATI 718 Plus (718Plus) at high temperature of 650 °C. LSP led to severe surface plastic deformation, which, in turn, led to a high magnitude of surface compressive residual stresses and changes in the near-surface microstructure which caused high surface hardening. This change in the near-surface microstructure was in the form of high dislocation density forming dislocation entanglements and slip bands and formation of near-surface nanoscale sub-grains/crystallites that remained stable at elevated temperatures. In addition, LSP retained ∼−470 MPa residual stress (68% of its initial residual stress) even after 140 h exposure to 650 °C. The retained residual stresses and the stable microstructure from the LSP increased the yield strength by ∼14% (∼140 MPa) and endurance limit by ∼10% (∼90 MPa) in corresponding tests at 650 °C. This improvement in fatigue life was attributed to near-surface microstructure, hardening and high compressive residual stress. The estimated crack growth rates were 72% lower for LSP-treated 718Plus as compared with untreated material. The thermal-mechanical residual stress relaxation indicates the effectiveness of LSP in improving the fatigue life of 718Plus at 650 °C.

The effects of Laser Shock Peening (LSP) on the microstructure, residual stress, hardness, strength, and fatigue life of ATI 718 Plus (718Plus) alloy was investigated and the results are reported. Microstructure before and after LSP and after mechanical testing was characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD)/orientation imaging microscopy (OIM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). LSP led to severe surface plastic deformation, which, in turn, led to a high magnitude of surface compressive residual stresses (∼−725 MPa) and changes in the near-surface microstructure. This change was in the form of high dislocation density forming dislocation entanglements and slip bands and formation of a few near-surface sub-grains, which, in turn, caused high surface hardening (∼8.3 GPa). In addition, a 16% increase in the yield strength (∼175 MPa) and around 15% increase in the endurance limit (∼110 MPa) occurred in corresponding tests at room temperature. The improvement in fatigue life was due to the shielding and resistance to crack initiation that the LSP treatment provided to the material through the near-surface microstructure, hardening and high compressive residual stress. This shielding also hindered crack propagation, lowering its rate to a third compared with baseline. Results of studies of stress relaxation with cycles showed how the LSP shield was affected by cycling and, in turn, the improvement in fatigue life of 718Plus. The results have demonstrated that LSP is a powerful surface engineering technique that can improve mechanical properties and fatigue performance of many important metallic materials.

The surface of Ti-6Al-4V was treated mechanically by applying ultrasonic nanocrystal surface modification. The effect of this treatment on the hardness, compressive residual stresses and fatigue performance were investigated. It is shown that in terms of the measured nanoindentation hardness values and the presence of compressive residual stresses, the treated sample only differed from the as-received sample in the first 200–300 µm area far from the surface. Also, the microstructure very close to the treated surface (

Among metal additive manufacturing technologies, additive friction stir deposition stands out for its ability to create freeform and fully-dense structures without melting and solidification. Here, we employ a comparative approach to investigate the process-microstructure linkages in additive friction stir deposition, utilizing two materials with distinct thermomechanical behavior—an Al-Mg-Si alloy and Cu—both of which are challenging to print using beam-based additive processes. The deposited Al-Mg-Si is shown to exhibit a relatively homogeneous microstructure with extensive subgrain formation and a strong shear texture, whereas the deposited Cu is characterized by a wide distribution of grain sizes and a weaker shear texture. We show evidence that the microstructure in Al-Mg-Si primarily evolves by continuous dynamic recrystallization, including geometric dynamic recrystallization and progressive lattice rotation, while the heterogeneous microstructure of Cu results from discontinuous recrystallization during both deposition and cooling. In Al-Mg-Si, the continuous recrystallization progresses with an increase of the applied strain, which correlates with the ratio between the tool rotation rate Ω and travel velocity V . Conversely, the microstructure evolution in Cu is found to be less dependent on Ω , instead varying more with changes to V . This difference originates from the absence of Cu rotation in the deposition zone, which reduces the influence of tool rotation on strain development. We attribute the distinct process-microstructure linkages and the underlying mechanisms between Al-Mg-Si and Cu to their differences in intrinsic thermomechanical properties and interactions with the tool head.

We find that PIPE issues that do not provide any protections to investors convey positive information about the firm and result in positive announcement period returns. However, PIPE issues that provide protections do not convey any new information about the firm and hence do not result in significant positive or negative announcement period returns. PIPE issuers that offer no protections to investors outperform their matched portfolios for up to 9 months after the issue. PIPE issuers that offer protections underperform their matched portfolios for 18 to 36 months after the issue.

The effects of thermomechanical processing (TMP) with iterative cycles of 10% cold work and strain annealing, on corrosion and stress corrosion cracking (SCC) behavior of alloy 600 was studied. The associated microstructural and cracking mechanisms were elucidated using transmission (TEM) and scanning electron microscopy (SEM), coupled with precession electron diffraction (PED) and electron back scatter diffraction (EBSD) mapping. TMP resulted in increased fraction of low coincident site lattice (CSL) grain boundaries whilst decreasing the connectivity of random high angle grain boundaries. This disrupted random grain boundary network and large fraction of low CSL boundaries reduced the propensity to sensitization, i.e. carbide precipitation and Cr depletion. After TMP, alloy 600 (GBE) also showed higher intergranular corrosion resistance. Slow strain rate tests in 0.01 M Na 2 S 4 O 6 solution at room temperature show TMP lowered susceptibility to intergranular SCC. To better understand the improvements in corrosion and SCC resistance, orientation maps of regions around cracks were used to analyze the interactions between cracks and various types of grain boundaries and triple junctions (TJs). Detailed analysis showed that cracks were arrested at J1 (1-CSL) and J2 (2-CSL) type of TJs. The probability for crack arrest at special boundaries and TJs, calculated using percolative models, was found to have increased after TMP, which also explains the increase in resistance to corrosion and SCC in GBE alloy 600. A clear correlation and mechanistic understanding relating grain boundary character, sensitization, carbide precipitation and susceptibility to corrosion and stress corrosion cracking was established.

In this study, the effects of ultrasonic nanocrystal surface modification (UNSM) treatment on the surface integrity, microstructures and wear resistance of 300M ultra-high strength steel (300M steel) were investigated. The results showed that surface roughness of 300M steels after UNSM processing was significantly decreased with a lower scanning speed even though the surface roughness values were higher than that of mechanically polished control samples. In addition, the surface hardness of 300M steel was significantly enhanced as the static load increased. It was found that using a static load of 50 N and a scanning speed of 250 mm/min in the UNSM process can significantly improve surface hardness (797 HV) while slightly increasing the surface roughness. With these parameters, the resulting microstructure of UNSM-processed samples have three layers: the layer of severe plastic deformation, the layer with gradual plastic deformation, and the unaffected layer. Due to the plastic deformation, greater and deeper compressive residual stresses were induced in the UNSM-processed samples. In addition, the wear resistance of UNSM-processed samples was significantly improved, which was attributed to the refined martensite laths, work hardening and compressive residual stress.

The tribological performance of AISI 52100 substrates subjected to several surface treatments have been evaluated in rolling, sliding, and mixed mode contact. The surface treatments include a boron-doped diamond-like carbon (B-DLC) coating deposited by plasma-assisted magnetron sputtering, an ultrasonic nanocrystal surface modification (UNSM) technique used to generate severe plastic deformation in the near surface of the steel specimens, and a B-DLC coating applied to a UNSM pretreated surface. In general, the tribological performance of the duplex surface treatment was superior to that of the untreated specimens and of the specimens with the other surface treatments in rolling, sliding, and mixed mode contact. The improved tribological performance of the duplex process was attributed to the combination of increased wear resistance provided by the B-DLC coating and the grain refinement of the martensitic structure of the AISI 52100 imparted by the UNSM process that created a beneficial substrate/coating interface.

The efficiency of any electronic device is highly reliant on the charge-injection efficiency at the electrical contact and semiconductor interface. Black phosphorus (BP), a layered and highly anisotropic material is attractive for a variety of electronic and optoelectronic applications including vertically stacked devices with distinct top and bottom electrodes. This makes it imperative to ascertain the influence of contact materials on the charge injection in the out-of-plane configuration. Here, we explore four different contact materials (aluminium, ITO, gold and platinum) chosen based on their work functions relative to the chemical potential of BP. By monitoring the current-voltage characteristics in the out-of-plane direction, conclusions are drawn regarding the charge injection capabilities of these contact materials providing the base knowledge to design efficient BP based stacked devices.

We report herein the effects of Ultrasonic Nano-crystal Surface Modification (UNSM), a severe surface plastic deformation process, on the microstructure, mechanical (hardness, wear), wettability and biocompatibility properties of NiTi shape memory alloy. Complete surface amorphization of NiTi was achieved by this process, which was confirmed by X-ray diffraction and high-resolution transmission electron microscopy. The wear resistance of the samples after UNSM processing was significantly improved compared with the non-processed samples due to increased surface hardness of the alloy by this process. In addition, cell culture study demonstrated that the biocompatibility of the samples after UNSM processing has not been compromised compared to the non-processed sample. The combination of high wear resistance and good biocompatibility makes UNSM an appealing process for treating alloy-based biomedical devices.

In this paper, we demonstrate a novel method for grain boundary engineering in Alloy 600 using iterative cycles of ultrasonic nanocrystal surface modification (UNSM) and strain annealing to modify the near surface microstructure (~250 µm) for improved stress corrosion cracking (SCC) resistance. These iterative cycles resulted in increased fraction of special grain boundaries whilst decreasing the connectivity of random grain boundaries in the altered near surface region. A disrupted random grain boundary network and a large fraction of low CSL boundaries (Σ3–Σ27) reduced the propensity to sensitization. Slow strain rate tests in tetrathionate solutions at room temperature show that surface GBE lowered susceptibility to intergranular SCC. Detailed analysis of cracks using Electron Back-scattered Diffraction showed cracks arrested at J1(1-CSL) and J2 (2-CSL) type of triple junctions. The probability for crack arrest, calculated using percolative models, was increased after surface GBE and explains the increase in resistance to SCC.

Coupons of a Ni base super alloy, Inconel alloy 718 (IN718) were laser shock peened with and without an ablative layer and resulting microstructure and residual stress state were studied. Laser shock peening without a protective overlay results in both mechanical and thermal loading of the material, leading to melting and re-solidification on the surface along with deformation due to laser induced shock wave. The surface shows presence of a non-uniform recast layer which increases the roughness of the surface and also results in a tensile state of residual stresses on surface. The recast layer has areas with modified chemistry and shows presence of nano particles deposited on top of the matrix. In this study, recast layer formed in Inconel alloy 718 (IN718) as a result of laser shock peening without protective overlay was characterized and compared with surface condition of a sample peened with a protective overlay. These results are presented and discussed in relation with those of previous studies.

Sudden, unprecedented electric blackouts and outages come as a dampener for a system that thrives on electrical energy. Reliability and efficiency are essential features for any power grid system. The conventional power grid systems are incapable of making use of real-time information from consumer side as well as the supply end for a more efficient transmission. Smart grid system, in which tremendous research has been done and which has been improvised manifold over the past decade, helps in meeting the incessant fluctuations in power demand from a huge consumer population. Smart grid brings about automation in managing the energy requirements using a two way interactive system, i.e. its ability to fetch information from the user and supply ends and utilize it to improve the overall reliability and efficiency of the transmission lines. Incorporating smart energy meters along with smart grid could come a long way in conserving electricity apart from removing manual energy meter reading from the scene. Smart meters supply the required data for the smart grid which helps the grid in providing an automated response. The paper elucidates how smart meters help in digitally tackling the issue of energy conservation in the consumer end and the utility end.

In the cloud computing paradigm, load balancing is one of the challenges, With Tremendous increase in the users and their demand of different services on the cloud computing platform, fruitful or efficient usage of resources in the cloud environment became a critical concern. Load balancing is playing a vital role in maintaining the rhythm of Cloud computing. The performance metrics of load balancing algorithms in cloud are response time and waiting time. In this paper we mainly focus on two load balancing algorithms in cloud, Min-Min and Max-Min algorithm.

Till date we have seen many applications that have used the technology of Cloud but integrating Augmented Reality and Cloud is pretty new to everybody. This paper will help you understand how we can efficiently use the technology of Cloud in developing Location Based Augmented Reality application. A Location Based Augmented Reality application is an online mobile computing application that provides digital information to the user based on the user's geographical location. Here we make use of the Cloud in order to store and access the Location Based Augmented Reality application. This application is both compatible with iOS and android.

The idea is to upload files into cloud using gestures. A “Gesture” is form of a movement of part of the body, especially a hand or head, to express an action. The gesture used here is a tilt of the device in hand. The type of the file to be uploaded into cloud can be of either a picture or a video. This is accomplished using an application similar to gallery. To perform the task, the application is invoked to view a picture or video, when the device is tilted from its actual viewing position towards its left twice within a span of two seconds, the gesture is recognised and the currently viewed file is uploaded into the cloud. The cloud service used for uploading is Dropbox. The size of a video files is generally large and uploading it will take time, so the video size is reduced through a compression algorithm. There is a buffer which tracks the uploading part and will see to that, that the entire video is uploaded into the cloud. Thus, through this application the file can be uploaded into cloud through a gesture easily and effectively.

In this study, the effects of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of nickel based Alloy 600 in tetrathionate solution were investigated. The LSP induced compressive residual stresses and changes in the near surface microstructure, hardness were characterized. The effects of LSP on SCC susceptibility of Alloy 600 in tetrathionate solution were evaluated by slow strain rate tests and constant load tests. The results indicate a significantly longer time to failure and decreased susceptibility to SCC. These improvements were attributed to LSP induced compressive residual stresses, increased yield strength and hardening caused by near-surface microstructural changes.

In this study, the effects of Ultrasonic Nano-crystal Surface Modification (UNSM) on residual stresses, microstructure changes and mechanical properties of austenitic stainless steel 304 were investigated. The dynamic impacts induced by UNSM leads to surface nanocrystallization, martensite formation, and the generation of high magnitude of surface compressive residual stresses (−1400 MPa) and hardening. Highly dense deformation twins were generated in material subsurface to a depth of 100 µm. These deformation twins significantly improve material work-hardening capacity by acting both as dislocation blockers and dislocation emission sources. Furthermore, the gradually changing martensite volume fraction ensures strong interfacial strength between the ductile interior and the two nanocrystalline surface layers and thus prevents early necking. The microstructure with two strong surface layers and a compliant interior embedded with dense nanoscale deformation twins and dislocations leads to both high strength and high ductility. The work-hardened surface layers (3.5 times the original hardness) and high magnitude of compressive residual stresses lead to significant improvement in fatigue performance; the fatigue endurance limit was increased by 100 MPa. The results have demonstrated that UNSM is a powerful surface engineering technique that can improve component mechanical properties and performance.

In this paper, the results of a study aimed at understanding the specific role of microstructure on cyclic stress response, cyclic strain resistance, and cyclic stress versus strain response, deformation and fracture behavior of high strength alloy steel AerMet® 100 is presented and discussed. The cyclic strain amplitude-controlled fatigue properties of this ultra-high strength alloy steel revealed a linear trend for the variation of log elastic strain amplitude with log reversals-to-failure, and log plastic strain amplitude with log reversals-to-failure. Cyclic stress response revealed a combination of initial hardening for the first few cycles followed by stability for large portion of fatigue life before culminating in rapid softening to failure at the lower cyclic strain amplitudes and intermediate cyclic strain amplitudes and resultant enhanced cyclic fatigue life. Fracture characteristics of test specimens of this high strength alloy steel were different at both the macroscopic and fine microscopic levels over the entire range of cyclic strain amplitudes examined. Both macroscopic and fine microscopic observations revealed fracture to be essentially ductile with features reminiscent of locally occurring ductile mechanisms. The intrinsic microscopic mechanisms governing stress response, deformation characteristics, fatigue life and final fracture behavior are presented and discussed in light of the competing and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents, cyclic strain amplitude and concomitant response stress.

Laser shock peening (LSP) induced residual stresses significantly affect the high cycle fatigue behavior of certain metals and alloys. Residual stress distribution is a function of various laser parameters (energy, laser pulse width, and spot diameter), the geometry, the material and the laser shot sequencing. Considering the wide range of parameters involved in the LSP process, a numerical approach based on 3D nonlinear finite element method has been employed to explore the relation between the processing parameters and the residual stress distribution. This methodology is applied to a thin coupon of Ti–6Al–2Sn–4Zr–2Mo (Ti-6242) alloy, with a view towards establishing conditions for obtaining through-thickness compressive residual stresses and hence improved bending fatigue life. Material response at very high strain rates in the LSP process is effectively represented using the modified Zerilli–Armstrong material model. The numerical approach is verified by comparison with the experimental results. Effects of laser parameters and laser shot sequencing on final residual stress distribution are studied by performing full scale simulations of LSP patches constituting a large number of laser shots. Based on simulation studies, optimal set of parameters is obtained that produces through thickness compression, which leads to a substantial improvement in bending fatigue life. Fatigue testing results support the recommendations made based on simulation results.

We examine a sample of 670 firms that announce asset purchases. We hypothesize that buyer announcement returns should be higher in the presence of better monitoring and better governance. Consistent with the monitoring hypothesis, we find that buyers with higher private debt make purchase decisions that increase shareholder value. Consistent with the governance hypothesis, we find that returns are higher for buyers that have lower antitakeover provisions in place. Consistent with the managerial discretion hypothesis, buyer announcement-period returns increase with buyer leverage. Consistent with the liquidity hypothesis, we find that announcement-period returns decrease with the seller's Z-score, suggesting that buyers benefit from the lower liquidity of assets sold by sellers with lower debt capacity and higher financial distress. We also find that buyer announcement-period returns are directly related to their operating performance in the post-purchase year.

Mechanical surface enhancement techniques are used to introduce compressive residual stresses to enhance the fatigue life and corrosion resistance of metallic components. In this study, we compare the effects of three advanced mechanical surface enhancements treatments: laser shock peening, cavitation shotless peening and ultrasonic nano structure modification on residual stress, hardness, plastic deformation and changes in near surface microstructure introduced in a Ni-Base superalloy, IN718 SPF(Super plastic forming). Coupons of the alloy were peened using two different conditions of each treatment and results compared to achieve a better understanding of underlying mechanisms of these techniques. Results indicate that there are significant differences in mechanisms of these surface treatments leading to differences in material response.