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Microstructural quantification of austenite and ferrite phases during isothermal bainite transformation (IBT) is paramount to tailor properties in low-carbon carbide-free bainitic steel. Such quantification carried out at the end of IBT heat treatment through microstructural analyses is fraught with limitations, such as non-consideration of transformation of the untransformed austenite on cooling post IBT. The current work has, therefore, devised a simple model to quantify volume fractions and the average carbon contents of bainitic ferrite and different austenite regions, namely film and blocky present between ferrite platelets and between bainitic sheaves, respectively, formed during IBT treatments at 375 to 450 °C from dilatometric strain itself. Such quantification, through other means would be very demanding in terms of experimentation and characterization. Microstructural quantification from the devised model is validated with experimental findings and highlights the difference in carbon contents of film and blocky austenite during IBT treatments. [Display omitted] [ABSTRACT FROM AUTHOR]

Dynamic analysis of structures using Finite elements largely needs to handle Mass, Stiffness matrices and Excitation vector. Lumping of Mass matrix is well established and its computational advantage recognized. Dynamic analysis of rotors additionally requires handling of skew symmetric Gyroscopic matrix which makes the solution difficult and solvers complicated. The present work attempts to lump Gyroscopic matrix. In real co-ordinates, the Gyroscopic matrix is skew symmetric. If Gyroscopic effect of disc is only considered, off diagonal skew symmetric terms appear at limited degrees of freedom. However, if gyroscopic effect of shaft is also considered, the off diagonal skew symmetric terms are present throughout. Use of complex co-ordinates diagonalizes the skew symmetric terms due to discs only. However, if distributed gyroscopic effect of shaft is considered, the Gyroscopic matrix becomes symmetric but non-diagonal. Since gyroscopic effect like mass appears due to inertia, the present work attempts to lump Gyroscopic matrix in complex co-ordinates. [ABSTRACT FROM AUTHOR]

The present work aims at stability analysis of a uniformly precessing and nutating viscoelastic beam with a tip mass as a simple model of a polymeric mechanical arm. The motion of the beam is described as small deformations superposed on rigid body rotation about a point. The damping in the viscoelastic material is considered to be of non-viscous type. The material is modeled in the time-domain using a Voigt model and Maxwell model in parallel. The resulting parametric equations are derived in a rotating frame and analyzed using a variant of Hill's method. The stability borderlines are generated with precession and nutation speeds as parameters for materials with different frequency versus storage modulus and loss coefficient graphs. It is observed that the beam, which only precesses is also unstable for a certain range of non-zero nutation angles. [ABSTRACT FROM AUTHOR]

The present work proposes a new shaft element for viscoelastic rotors in a spinning frame. The Maxwell-Wiechert viscoelastic material model which has one elastic branch and several parallel Maxwell branches of elastic and viscous elements in series is considered here. This model considers additional internal or damping variables between elastic and viscous elements. Here, the stress depends not only on the elastic strain and elastic strain rate but also on additional strains and their rates. In the present work, it is assumed that these additional strains can be derived from continuous fictitious displacement variables in the same way as the elastic strains are derived from the actual displacement variables. These continuous fictitious displacements in turn are interpolated from their nodal values using the conventional beam shape functions. Therefore, in addition to the standard degrees of freedom, extra degrees of freedom are defined at the nodes. [ABSTRACT FROM AUTHOR]

In this study, we report the investigation of microstructural and mechanical property changes in binary Zr−2.9 wt% Sn alloy induced by room temperature heavy ion (Ar9+) irradiation to fluences ranging from 3.1 × 1015 to 4.17 × 1016 Ar9+cm-2. S-parameter, probed using positron annihilation spectroscopy, showed an increase with fluence. Changes in microstructural attributes, viz., the coherently scattering domain size, microstrain, dislocation density and, residual stress, were ascertained through grazing incidence X-ray diffraction. A decrease in domain size and increase in both microstrain and dislocation density were observed in addition to the development of compressive stress in place of tensile after irradiation. The hardness of the irradiated samples, probed by nanoindentation, was found to be higher in comparison to unirradiated one. Transmission electron microscopy investigation exemplified the formation of - and - type dislocation loops upon irradiation. The above findings could be rationalized on the basis of the defects generated during Ar9+ heavy ion irradiation. • Ar9+ ion irradiation of binary Zr − 2.9 wt% Sn alloy. • Distribution of defects observed experimentally. • Domain size, microstrain and dislocation density characterization using GI-XRD. • Change in nature of residual stress from tensile to compressive upon irradiation. • Characterization of dislocation loops and probing of irradiation hardening. [ABSTRACT FROM AUTHOR]

Abstract: The crystallographic aspects associated with the formation of the γ hydride phase (fct) from the α (hcp) phase and the β (bcc) phase in Zr–Nb alloys have been studied in two distinct situations, viz., in the α matrix in pure Zr and Zr–2.5Nb and in the β matrix in β stabilized Zr–20Nb alloy. The β–γ formation can be treated primarily as a simple shear on the basal plane involving a change in the stacking sequence. A possible mechanism for α–γ transformation has been presented in this paper. In this paper the β→γ transformation has been considered in terms of the invariant plane strain theory (IPS) in order to predict the crystallographic features of the γ hydride formed. The lattice invariant shear (LIS) (110)β ||(111)γ has been considered and the crystallographic parameters associated with bcc→fct transformation, such as the habit plane and the magnitude of the LIS and the shape strain have been computed. The predictions made in the present analysis have been compared with experimentally observed habit planes. The α/γ and β/γ interface has been examined by high resolution transmission electron microscopy (HRTEM) technique to compare with the interfaces observed in martensitic transformations. [Copyright &y& Elsevier]

The possibility of solidification of unalloyed zirconium and zirconium–niobium alloys from the liquid phase directly into the low temperature α phase is examined and the role played by solidification microstructure in modifying the β to α′ martensitic transformation in rapidly solidified zirconium and zirconium–niobium alloys is discussed. [Copyright &y& Elsevier]

Abstract: Understanding the effect of nitrogen content on the crack growth rate (CGR) due to intergranular stress corrosion cracking (IGSCC) in high temperature (288°C) pure water, in non-sensitised and strain-hardened stainless steel (SS) type 304 LN was the focus of this study. Non-sensitised SS containing two different levels of nitrogen (0.08 and 0.16wt.%) in the solution annealed condition was strain-hardened by cross-rolling at 200°C (warm rolling). It has earlier been reported that SS with a higher nitrogen level in the warm rolled condition has a higher CGR in high temperature pure water. Tensile testing was carried out using both the SS in the warm rolled as well as in the solution annealed condition at 288°C. Samples were prepared for transmission electron microscopy (TEM) from the warm rolled SS and from the tensile tested (at 288°C) specimens. TEM studies indicated that twinning and shear band formation were the major modes of deformation due to rolling at 200°C and these feature were observed to terminate at grain boundaries, leading to regions of higher strain and stresses at grain boundaries. Higher nitrogen SS has higher grain boundary strain and stresses making the grain boundary regions more susceptible to IGSCC, resulting in higher CGR values. At 288°C dislocation entanglement and cross-slip were the predominant modes of deformation. [Copyright &y& Elsevier]

Abstract The changes in the microstructure of 3.5 MeV proton irradiated T91 Ferritic-Martensitic steel samples with dose have been evaluated using detailed X-ray diffraction line profile analysis of the data collected using both laboratory and the synchrotron source. Different line profile analysis techniques like Williamson-Hall, modified Rietveld method and convolutional multiple whole profile fitting have been applied to evaluate the microstructural parameters such as domain size, microstrain, dislocation density and the character of the dislocation from both the data. The coherent domain size decreases and the corresponding microstrain increases at the first dose of irradiation. With further irradiation, these parameters show a slight recovery and eventually tend towards saturation with increasing dose. The dislocation density follows similar trend as the microstrain showing saturation at higher doses of irradiation in both the XRD data. However, a systematic change in the character of the dislocation from screw-type to edge-type could be ascertained only from the data obtained using synchrotron source. The Vickers microhardness of the samples is found to increase continuously with increasing irradiation dose supporting the observed change in the dislocation character from screw-type (glissile) to edge-type (sessile). Both EBSD and TEM analysis of the unirradiated and irradiated samples have supported the results obtained from the XRD analysis. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Mechanical properties of nanocrystalline (nc) Nickel (Ni) and Ni-Teflon (Ni-Tf) nanocomposite has been studied in detail using nanoindentation and conventional tensile tests. Nanoindentation tests carried out at room temperature over a range of loading rate exhibited higher hardness for the nanocomposite as compared to the nc-Ni due to Tf dispersion. An increase in strain rate sensitivity (SRS) and decrease in activation volume of the nanocomposite as compared to nc-Ni was also observed. Tensile tests were carried out over a temperature regime of room temperature (RT) to 500 °C. Tensile data also showed enhancement of yield stress and ultimate tensile strength up to 150 °C. But from 200 °C and above, Tf dispersion is unable to provide superior strength over nc-Ni as both the materials show almost similar strength. However, the ductility of the Ni-Tf nanocomposite was observed to be higher at all temperature compared to the pure nc-Ni. SRS was found to increase with temperature while SRS in nanocomposite had higher value below 200 °C. The present study reveals that Ni-Tf nanocomposite possess better strength and ductility compared to nc-Ni up to 200 °C. [ABSTRACT FROM AUTHOR]

Highlights: [•] The paper constructs the stability borderline for a uniformly precessing and nutating beam with tip mass. [•] A simple two degree of freedom model with centrifugal stiffening is considered. [•] It is found that an only nutating beam is always stable. [•] An only precessing beam is unstable within a range of constant nutation angles. [ABSTRACT FROM AUTHOR]

• Effect of proton irradiation on Nb-1Zr-0.1C alloy proposed for CHTR. • XRD line profile analyses of the data collected using synchrotron source. • Prediction of dislocation loop formation with XRDLPA and supported by TEM analysis. • Microstructure-mechanical property correlation by tensile and nanoindentation test. • Comparison of microstructure and mechanical properties with proton irradiated pure Nb. The microstructural evolution and corresponding changes in mechanical properties of proton irradiated Nb-1Zr-0.1C alloy have been studied as a function of irradiation dose. Different XRD line profile analyses (XRDLPA) have been carried out using synchrotron XRD data to evaluate the microstructural parameters. It is observed that coherent domain size decreases with an increasing microstrain within the domain as a function of dose. The dislocation density also increases and shows saturation at the highest dose. The Wilkens arrangement parameter decreases as a function of dose indicating the formation of correlated dislocations in the alloy matrix. Transmission electron microscopy (TEM) analysis confirms the presence of dislocation loops in the highest dose sample supporting the findings of XRDLPA. The strength and ductility of unirradiated and all irradiated samples have been evaluated as a function of dose. It is observed that the ductility reduces continuously along with increasing yield strength (YS) and ultimate tensile strength (UTS) as a function of dose. Nanoindentation was also carried out to measure the change in hardness of the alloy with dose. It is observed that the value of the nanohardness increases continuously from 1.74 GPa for the unirradiated sample to 2.43 GPa in the highest dose irradiated sample. Systematic changes are observed on the morphology of fracture surface as a function of dose. Signature of ductile failure is observed in the unirradiated sample whereas brittle failure is prominent in the irradiated samples with higher dose. The change in microstructure in terms of dislocation density is corroborated with the change in mechanical properties in terms of YS of the irradiated alloy. Contradistinction of the findings of Nb-1Zr-0.1C with those of pure Nb contemplated the role of the alloying additions, especially carbon, in governing the irradiation behaviour of the alloy. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Fully recrystallized Zircaloy 2 was subjected to hydride formation through gaseous hydrogen charging. Primarily grain boundary hydrides were observed. To describe the relative preference, if any, a hydride preference index (HPI) was proposed: HPI Q = f h,Q /f r,Q , where f h,Q and f r,Q are the respective fractions of Q-type boundary present among hydrided boundaries and present in the total sample. HPI Q values were estimated from 1200 distinctly hydrided boundaries and showed a clear preference for hydride formation and grain boundary nature. Coincident site lattice boundaries were, in general, resistant to hydride formation. Elastically harder grains or orientations also arrested the formation of hydrides. The study indicates a clear possibility: a previously unknown/uncharted possibility of suitably ‘tailored’ zirconium microstructures, microstructures with reduced potential for ‘hydride embrittlement’ and delayed hydrogen cracking. [Copyright &y& Elsevier]

Synchrotron X-ray diffraction data (SXRD) has been used to characterize the microstructural changes in 3.5 MeV proton irradiated 2.25Cr–1Mo (T22) steel samples as a function of dose through different techniques of X-ray diffraction line profile analysis (XRDLPA). Williamson-Hall (W–H) method, modified Rietveld method and convolutional multiple whole profile (CMWP) fitting technique have been used to evaluate the coherent domain size, r.m.s microstrain, dislocation density and dislocation character from SXRD data. It is demonstrated that XRDLPA from SXRD data is a powerful tool for extracting the microstructural parameters of irradiated samples in a reliable manner. Transmission Electron Microscopy (TEM) investigation has been carried out on unirradiated and irradiated samples to corroborate the results of XRDLPA. It is observed that dislocation density increases with dose and forms dislocation loops at highest dose. Vickers microhardness measurement has also been carried out to get the information on the mechanical property changes with dose. The variation in Vickers microhardness as a function of dose has been explained using the results from XRDLPA and TEM analysis. • Proton irradiation of T22 Ferritic-Martensitic steel samples. • X-ray diffraction line profile analysis of the synchrotron XRD data. • Evolution of dislocation character with dose. • Findings supported by TEM analysis. • Mechanical property in terms of micro hardness measurement. [ABSTRACT FROM AUTHOR]

Most of the layered metal oxides are relatively "open" structures and eventually find use in applications where charge intercalation or de-intercalation is critical. One of the limitations of layered structures is that they have a tendency to collapse after repeated cycling. In this study, it is established that use of single-phasic marteyite-type layered (Zn 3 V 2 O 7 (OH) 2 ·2H 2 O) can be effectively extended in the field of energy storage devices. The pyrovanadate groups act as pillars and prevent the brucite-like Zn–O layers from collapsing. To induce further enhancement in the already stable materials, it is shown that the surface characteristics of these particles, with floriated morphology, can be easily tuned by tailoring the annealing temperature. Contrary to expectation, both the surface area and capacitive behavior showed improvement when the sample was annealed post-hydrothermal treatment for longer durations. Careful analysis, using large number of techniques, establish that this observation can be attributed to atomic rearrangement in the crystal unit cell and formation of cross-linked type particle morphology. This would lead to efficient path for charge transfer, which originate at the electrode-electrolyte interface. The samples showing interlinkages in the pores could deliver specific capacitance of ∼383 F g−1, which was ∼2.5 times higher in comparison to original porous particles. The particles continued to have ∼90% capacitance retention after 2000 cycles, which shows their potential as energy storage materials. • Supercapacitor application of layered zinc pyrovanadate with floriated microstructure. • Duration of hydrothermal treatment positively affects electrochemical performance. • Heat treatment at 300 °C transforms layered structure to highly porous. • 230% increment in specific capacitance due to heat treatment. • Evolution of interlinked pores as channels: increased surface for charge storage. [ABSTRACT FROM AUTHOR]

In the present study the irradiation damage behavior of Zr-1 wt.% Nb fuel cladding alloy was investigated using X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), transmission electron microscopy (TEM) and nano-indentation. The samples were irradiated at two different fluences of 5 × 1016 p/cm2 and 1 × 1018 p/cm2 using proton beam of 3.5 MeV energy at room temperature. SRIM calculation showed an inhomogeneous damage distribution as a function of proton penetration depth with maximum damage at a depth of 68 μm. XRD analysis revealed variation in the microstructural parameters of irradiated samples after proton irradiation. PALS showed formation of open volume defects in the irradiated samples and a clustering tendency of the same with irradiation. The formation of − and − type dislocation loops and needle-shaped precipitates upon irradiation was demonstrated by TEM. The depth dependent hardness of the irradiated samples evaluated from nano-indentation technique was found to follow the damage distribution predicted by SRIM simulation. [ABSTRACT FROM AUTHOR]