ABSTRACT Understanding the evolution of dislocations and twinning at the crack front is critical for designing micro-mechanical systems with improved performance. In this work, the dislocation evolution at the crack front in thin pre-cracked FCC single crystals is correlated with the associated fracture toughness, which is shown to be dependent on material specific properties such as stable stacking

ABSTRACT We employ molecular dynamics simulations to investigate the evolution dynamics of { 10 1 ¯ 2 } twinning in single-crystal Ti under shock loading. The shock compression applied perpendicular to the c-axis leads to the activation of { 10 1 ¯ 2 } twins in single-crystal Ti. We find the twin variant activation for each case of the applied loading conditions follows Schmid criterion. However, the

ABSTRACT High-temperature oxidation behaviour of an alumina-forming austenitic (AFA, Febalance–20Ni–14Cr–2.5Al–0.15Si–2Mn–2.5Mo–0.9Nb, in wt%) steel and W-substituted AFA steel was examined. The isothermal oxidation tests were performed on the two steels at 780°C for 2 weeks in air, which indicated that the substitution of W for Mo was beneficial to improve the oxidation resistance of the AFA steel

ABSTRACT The spin-polarized full-potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT) and the exchange and correlation potential is treated with the generalized gradient approximation (GGA) and the Coulomb repulsion (GGA + U), as well as the modified Becke-Johnson approach (GGA-mBJ) are investigated on the structural, elastic, electronic and magnetic

ABSTRACT Similarity has been proven between the Lifshitz topological transitions (LTT) in AB-stacked trigonally warped bilayer graphene (TWBG) and graphite near K points. The density of states (DOS) has been shown to have the van Hove singularities (VHS) of type ( ϵ c − | ϵ | ) − 1 / 2 at LTT in AB-stacked (TWBG) and graphite near K points. The topology evolutions of the iso-energetic lines at LTT

ABSTRACT Natural pyrrhotites have gained significant attention due to their interesting electronic, antimicrobial, and chemical properties. The present work attempts to explore the morphology-induced modifications in the thermal characteristics of natural pyrrhotite due to ageing. The morphological, elemental, structure, optical, and thermal characterisations help in understanding the effect of ageing

ABSTRACT We investigate the effects of a time-dependent gate voltage on a spin–orbit interaction (SOI) coupled interacting double quantum dot (DQD) system. For a tunnel coupled detuned DQD with two interacting electrons, SOI couples triplet T 0 and hybridised singlet state (1,1)–(0,2) through spin nonconserving transition. In order to explore the effects of Ac gate voltage on charge localisation, we

ABSTRACT The present study deals with the properties of boronized and non-boronized low-alloy steel (34CrAlMo5-10). Specimens are characterised using microscopy, various spectroscopic techniques, nanoindentation, surface profilometer, and tribometer. The boronized region contains (i) (Fe, M)2B columns and (ii) matrix between the columns. Nanoindentation study reveals the difference in the mechanical

ABSTRACT We discuss surface roughness effects on the conduction of electrons in metals using both the quantal Kubo–Greenwood formalism and the semi-classical Fuchs–Sondheimer method. The main purpose here is to compare these methods and clarify a few subtle and widely misunderstood conceptual issues. One of such issues is concerned with the conditions under which the broken translation symmetry along

ABSTRACT We employ molecular dynamics simulations to investigate the role of temperature on the evolution dynamics of the voids in single crystal iron. We simulate isotropic tension in single crystal iron at a constant strain rate with temperature in the range of 300–1200 K. We find that the number of voids is highest at 1200 K in comparison to that at 300 K indicating high nucleation events at high

ABSTRACT In this report, SrFeO3-δ nanoparticle perovskite sample was prepared by the co-precipitation method. Rietveld refinement of the X-ray diffraction (XRD) data of SrFeO3-δ sample showed that it has a cubic phase (space group: Pm3 m). The morphology and average size (11.15 nm) of the SrFeO3-δ nanoparticle samples were characterised by the high-resolution transmission electron microscope (HRTEM)

ABSTRACT In this paper, the influence of growth rates on the microstructure and magnetostrictive properties of Fe83Ga17 directional solidification alloys were investigated. The microstructure and magnetic properties of Fe83Ga17 as-cast and directional solidification samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), optical

ABSTRACT Non-uniform height semiconductor quantum rings are studied in order to determine their electronic and optical absorption properties. Theoretical modelling of the structure includes an analytical description of the non-regular multi-hilled confining potential as well as the presence of repulsive scattering centre and external crossing electric and magnetic fields. We have discussed the features

ABSTRACT The temperature, hydrostatic pressure, and external electric field effects on the confined exciton in cylindrical quantum dots by considering a parabolic confining potential are investigated. The effects of these external perturbations on the binding energy and interband emission energy are calculated numerically by adopting the variational method within the effective mass approximation. Our

ABSTRACT As a class of typical topological structures, polarisation vortexes were characterised by the intensity vector which is defined as the curl of the polarisation at their cores. Some phase field simulations were conducted on the lead titanate nanofilms to evaluate the effects of model size, temperature, traction, and curled electric field on the formation and evolution of polarisation vortex

ABSTRACT The energies of small-angle tilt grain-boundaries have been predicted using the Read–Shockley model based on dislocation theory. However, experimentally observed energies have been inconsistent with the Burgers vector-dependent values derived from this theory. Finite-temperature predictions of grain-boundary energies, performed via first-principles calculations, show consistency with the experimental

ABSTRACT The plates of an Fe–12%Mn–0.5%C–1.5%Al austenitic steel with an original grain size of 80 µm were subjected to friction stir welding using a spherical welding pin. The fine grained microstructures with a grain size being dependent on the welding feed speed were evolved in the stir zones. The microstructure evolution in the stir zone resulted from a kind of post-dynamic recrystallisation. An

ABSTRACT Adopting a unique electrical circuit design, here we treat a significant low-cost engineering material (eutectoid steel not containing costly alloying elements) with a high-voltage (100 kV) low-current (150 mA) energy input (energy level exceeding cohesive energy). A distinctive structural evolution is ascertained with treatment duration of only 5 min as an outcome of lamellar fragmentation

ABSTRACT The dynamical evolution of smectic-C liquid crystals in the presence of a magnetic field is studied. The theoretical analysis is based on dynamic renormalisation group techniques. The starting point of the analysis is the nonlinear elastic model of smectic-C liquid crystals followed by Langevin formulation. The dynamical model predicts the onset of Kosterlitz-Thouless transition at low frequency

ABSTRACT The lack of interstitial oxygen for locking and pinning of dislocations has made the ultra-high resistivity silicon wafers for radio frequency applications prone to slip and warpage during electronic device manufacturing. In this work, we investigate the role of germanium doping on the dislocation mobility in very low oxygen concentration, Czochralski-grown silicon wafers. Mechanical bending

ABSTRACT The aim of this article is to provide the displacement field of a straight dislocation in gradient elasticity that can be implemented in dislocation dynamics simulations. The displacement and plastic strain fields of a dislocation depend on the history of the dislocation motion. The cut surface (or the branch cut) represents this history. When an edge dislocation glides, the branch cut must

ABSTRACT Using first principle calculations based on the density functional theory (DFT), the structural, elastic, electronic, and thermoelectric properties, and thermodynamic stability of the LiMgZ (Z = P, As, Bi) half-Heusler ternary compounds were studied. The results of structural calculations and elastic constants and investigation of the thermodynamic phase diagram represent stability for these

ABSTRACT Memory effects generated by a prolonged transverse electric field in the triglycine sulphate (TGS) ferroelectric were investigated quantitatively. Four characteristic temperatures were introduced, TS ≤ TA ≤ TH   < TC, where TC is a para-ferroelectric critical temperature. Measurements of depolarizing transverse electric current carried out in heating from TS (or TA) up to above TC were preceded

ABSTRACT Classical molecular dynamics simulations have been performed to investigate the microstructural evolution of single crystal titanium under equal channel angular extrusion process (ECAE). The ECAE loading condition has been simulated by constraining deformation along two directions and applying shear along one direction. We find that for the case where shear is applied along < 2 1 ¯ 1 ¯ 0 >

ABSTRACT The properties of the specific heat and elastic stiffness components at the charge density wave phase transition in several one-dimensional and two-dimensional materials are examined. Here we show that the thermodynamic properties of the rare earth tritelluride R Te 3 ( R = Te , Er) and Lu 5 Ir 4 Si 10 compounds can be explained in the framework of a standard mean field Landau theory. The

ABSTRACT We use nanoindentation to perform elastic cycling on, and to characterise, the bulk metallic glass Cu46Zr46Al7Gd1. From multiple loading curves, cumulative distributions are determined for several properties, including the initial yield load, the hardness and the indentation modulus. The distributions are characterised by the median property value and by their width. The effects of elastic

ABSTRACT I comparatively determine the structural and electronic properties of Li2FePO4F compounds with F substituted by Cl, Br and I atom using the spin density functional theory with Perdew–Burke–Ernzerhof generalised gradient approximation (GGA + U). The lattice parameters and volumes are improved by the dopants because of the greater atomic radius in dopants. Non-metal doping in Li2FePO4F reduces

ABSTRACT Ni2MnSb Heusler alloy is modelled and its magnetic properties are investigated by means of the effective field theory (EFT) developed by Kaneyoshi. Furthermore, the structural and electronic properties are performed by using density functional theory (DFT). According to DFT, with the help of volume-energy optimisation curves, the ferromagnetic (FM) state is more stable in energetic than the

ABSTRACT The main raising propose in material science is to modify the structural, electronic, optical and magnetic properties. Here, the effect of substituted VIB transition metals in In2O3 semiconductor is analysed utilising the spin density functional theory with the generalised gradient approximation (GGA) by Perdew–Burke–Ernzerhof (PBE) formulation. W doping in In2O3 semiconductor is the most

ABSTRACT Electrochemical Impedance Spectroscopy and Raman studies are performed on fast ion conducting, AgI–Ag2O–MoO3 glasses, over a wide range of composition to understand the features of structure, ion migration and their correlation. These features essentially involve diffusion and relaxation. The coefficients associated with diffusion process, especially, the diffusion coefficient, diffusion length

ABSTRACT A new approach accounting for the indentation size effect in metals with the dislocation mediated deformation mechanism is proposed in the paper. The model is based on the assumption that the number of dislocations contained in the ‘effective’ plastic zone under the contact area incrementally scales with the penetration depth with h m , which leads to the modification of the Nix-Gao model

ABSTRACT Semiconducting glassy chalcogenides (ChGs) have broad technological applications owing to the ability to tune their band gap through composition change. However, there is a lack of theoretical models predicting the band gap in ternary and quaternary compounds of these amorphous materials which are the most industrially used. After a critical review of some existing models concerning mainly

ABSTRACT Displacement damage in beryllium was predicted as a function of temperature and energy using molecular dynamics simulations. A key aim of this study was to determine if average results from large displacement cascades correspond to values predicted by the Kinchin–Pease (K–P) model. The number of residual defects remaining after 1 ps increased linearly with primary knock-on atom (PKA) energy

ABSTRACT Structural heritage between bulk metallic glasses (BMGs) and their relevant crystals has already been acknowledged. But how this kind of heritage is represented is still unclear. In the present paper, firstly, two important characters are considered to determine the principal cluster of crystal, i.e. the atomic-packing efficiency which is evaluated by atomic density radial distribution method

ABSTRACT Adsorption and desorption of CO 2 on metallic and oxidised Ni nano-structures supported on mica (muscovite) substrates have been studied by temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Predominantly physisorption was observed at low temperatures near 130 K. Weak desorption features were found at temperatures up to about

ABSTRACT The compressive creep deformation behavior of a Co-base single-crystalline superalloy is studied in the high temperature / low stress regime at 950°C/150 MPa. Emphasis is placed on the mechanisms causing the double minimum creep behavior consisting of a local and a global creep rate minimum. The local minimum occurs at ∼0.2% strain with dislocation accumulation at γ/γ′ interfaces after bowing

ABSTRACT Microstructure and mechanical properties of compacted graphite iron (CGI) alloyed with different additions of rare earth (RE) elements are analysed in this paper. Experimental results show that graphite presents mostly vermicular shape when the content of RE is less than 0.041%. The shape of graphite becomes spherical after more RE is added. Tensile strength is improved significantly with

ABSTRACT For modern engineering applications, the prediction of residual stresses is a starting-point for the subsequent optimisation of the design with regard to the process induced stresses on the macro and the grain scale. In this paper, a new approach for the numerically efficient prediction of phase-specific residual stresses (residual stresses of second kind) in two-phase materials is presented

ABSTRACT A dislocation assisted self-consistent model based on Tandon and Weng approach and Bergstrom dynamic recovery model for particulate-reinforced composites has been extended to consider the matrix evolution during high-temperature deformation on flow stress. The impact of main influential processing parameters such as temperature, strain, and strain rate in addition to reinforcement characteristics

ABSTRACT The superstructure and basic structure of ternary Yb-Cd-Mg 1/1 quasicrystal approximants with the compositions Yb 12.9 Cd 78.4 Mg 8.8 and Yb 13.3 Cd 64.2 Mg 22.5 were investigated using X-ray structural analysis. The former was determined to have a face-centred packing structure comprising two distinguishable Tsai-type rhombic triacontahedron clusters (space group F d 3 ¯ , a = 31.377 ( 1

ABSTRACT The present work describes the effect of Ni/Fe ratio on microstructure, tensile flow and work hardening behaviour of tungsten heavy alloys (WHAs) based on 92 wt. % W with varying Ni/Fe ratios in heat treated and swaged conditions. Evaluation of properties in the heat treated and swaged conditions reflect that the increasing Ni/Fe ratio has resulted in the enhancement of tensile as well as

ABSTRACT In this study, Ni2-x Co x MnSb full-Heusler alloys (1.00 ≤ x ≤ 1.75) were prepared by arc melting process, and examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and SQUID. The L21 crystal structure of the synthesised Heusler alloy was confirmed by XRD patterns, and it was observed that the use of Co instead of Ni caused a decrease in the interatomic distance. The magnetisation

ABSTRACT Hot extrusion (HEX) and isothermal forging (ITF) are two critical processing methods in manufacturing of Ni-based powder metallurgy (P/M) superalloys. Hot compressions with different parameters were performed on a novel Ni-based P/M superalloy in as-extruded condition to simulate ITF and the related microstructure evolution. The results revealed that the as-extruded alloy was fully recrystallised

ABSTRACT In the studies related to thermodynamic and structural functions of liquid alloys at high temperatures using linear temperature-dependent interaction parameters, in some cases, artificial miscibility gaps or artefacts are noticed. These artificial miscibility gaps in these functions at higher temperatures are usually asymmetric with respect to the concentration. The presence of the artificial

ABSTRACT The effect of transition elements, specifically Mn, Cr, V, and Mo, on dispersoid formation and mechanical properties in 6082 aluminum alloy was studied. The elevated-temperature mechanical properties were evaluated based on the compressive yield strength and creep resistance. The results indicated that the addition of Mn to the 6082 alloy resulted in the formation of a large number of the

ABSTRACT Despite a large body of literature, mechanisms contributing to low temperature jerky flow remain controversial. Here, we report a cross-over from a smooth at room and liquid nitrogen temperatures to serrated plastic flow at 4.2 K in high-entropy CrMnFeCoNi alloy. Several complimentary investigations have been carried out to get a coherent physical picture of low temperature jerky flow in these

ABSTRACT In this study, we present a detailed theoretical investigation of the effect of an externally applied magnetic field on the energy states 1 s , 1 p , 1 d and 1 f in the spherical quantum dot with finite and infinite confinement potentials. For both finite and infinite spherical quantum dot, the first four electron energies, Zeeman transition energies between these electronic states and optical

The influence of the volume fraction of nano-sized TiCN reinforcement additive on the mechanical properties and the microstructure of Al-based composite was studied. It was found that the addition of nano-sized TiCN particulates into the Al-matrix leads to a substantial improvement of the mechanical properties of the composite, TiCN-Al. However, the obtained results showed that the strengthening effect

ABSTRACT Material failure by white-etching-cracks (WECs) can cause enormous economic costs. The formation of WECs emerges from the decomposition of the original, usually cementite-containing, microstructure. As small amounts of electric current can trigger this failure mechanism, we investigate the contribution of electric current to cementite decomposition. We applied ∼700 A/cm2 for two weeks at 60°C

(2020). XV International Workshop on Complex systems Andalo (Trento) Italy. 17–20 March 2019. Philosophical Magazine: Vol. 100, Andalo special Issue on Complex systems, pp. 2543-2543.

We discuss the role of non-hydrodynamic processes in viscoelastic transition in pure liquids. In particular, using both analytical results and molecular dynamics simulations, we clarify the effect of the shear stress relaxation on the transverse dynamics. We use as an example the Lennard-Jones fluids. We analyse the frequency dependence of the shear modulus and its connection to the non-hydrodynamic

(2020). Publisher’s Note. Philosophical Magazine: Vol. 100, Andalo special Issue on Complex systems, pp. 2658-2658.

ABSTRACT In this paper, the austenite grain growth behaviour of 12Cr ultra-super-critical (USC) rotor steel was investigated by a series of heat treatments. The heat treatments at heating temperatures of 900°C–1250°C and holding time of 1 h–20 h were conducted in an electric box-type heating furnace. Experimental results showed that the sizes of austenite grain were affected by heating temperatures

(2020). Correction. Philosophical Magazine: Vol. 100, No. 19, pp. 2540-2541.

ABSTRACT In the paper, molecular dynamics simulation is applied to study the evolution and distribution of subsurface defects during nanoscale machining process of single-crystal copper. The chip-removal mechanism and the machined-surface-generative mechanism are examined through analysis of the dislocation evolution and atomic migration of the workpieces. The findings show that under different stresses

ABSTRACT Electronic, optical and magnetic properties of perovskite oxides PrXO3(X = V, Cr) are calculated by first-principle calculations. The calculations of electronic band structure and density of states (DOS) show that the PrVO3 exhibits metallic behaviour, while PrCrO3 exhibits half-metallic nature with direct band gap. The calculated band gap of PrCrO3 is 2.7 in the minority spin state. The origin

ABSTRACT Traditionally, for hard materials, two types of straight disclinations are identified although some Somigliana disclinations with different aspects have been treated theoretically. Here, we consider four physically distinct types of curved generalised disclinations, one of which reduces to two straight types, giving a total of five. We indicate typical applications for the different types

ABSTRACT Orientation rotation tendency with respect to target orientation in body-centred cubic (bcc) crystal is investigated under different rolling modes. Oriented stability is proposed to describe the rotation rate towards target orientation in contrast to conventional orientation stability. The oriented stability distribution in Euler space can clearly present how an orientation contributes to

ABSTRACT In the aluminum industry, the needs of predictability of the kinetics of precipitation during the artificial aging processes increase as the targeted applications require the maximisation of properties at the lowest costs possible. In this regard, kinetics modelling can be helpful to design the heat treatment processes. Despite using many fitting parameters, available models show a lack of

ABSTRACT Low-energy dislocation structure is one classical self-organised dislocation pattern, among which persistent slip band (PSB) ladders is the most representative. Periodically distributed PSB ladders consist of two phases: matrix phase and pattern phase. In the new two-phase model, the appearance of pattern phase results in the softening of PSBs with lower elastic constant. The formation of