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Tension and compression tests for a rare-earth-containing alloy sheet, Mg–1.9Mn–0.3Ce (wt-%), are performed under quasi-static and high-rate loadings along the rolling, transverse and normal direct...

The present study investigated the influences of Dy-addition on the microstructural characterization, functional behaviour and deformation mechanisms in high-temperature Ni54Mn25Ga21 alloys. The re...

Cellular solids’ acoustic properties, such as dispersion, direction dependence, and phase velocities, are inherently coupled to the dominant deformation modes in their ligaments. Understanding and ...

Quasi-static indentation tests were conducted to characterize the mechanical behavior of honeycombs. The local failure mechanisms of honeycombs with different relative density were discussed in det...

Introducing precipitates significantly improves the strength of metallic materials. In the present study, we elucidate the role of a precipitated Ti phase on the deformation mechanism in nanocrysta...

Dynamic compression experiments were carried out on Mg–2.5Zn–4Y magnesium alloy containing long period stacking ordered phase (LPSO) to understand its deformation mechanism using ‘Split Hopkinson P...

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 l...

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 numbe...

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, including particle size, and volume fraction, were successfully taken into account in the constitutive model. Moreover, the effect of particle fracture, diffusion relaxation around particles, dynamic recrystallization, and dynamic recovery of the matrix during deformation were precipitated as the softening factors in the presented model. It was found that the occurrence of particle stimulating nucleation mechanism can destroy the load transfer mechanism, which results in flow curve softening for a limited range of deformation conditions. It was shown that deformation mechanisms in single-phase alloy and metal matrix composite are the same, which are viscous glide and dislocation climb.

In this study, impact behavior and deformation mechanism of triply periodic minimal surface (TPMS) sheet (Schwarz’ P, Schoen’s I-WP, and Neovius) were numerically investigated. The convergence stud...

In this work, the microstructure and deformation mechanism, based on uniaxial tensile tests of 2507 super duplex stainless steel, is investigated using OM, XRD, EBSD, TEM and micro-Vickers. The exp...

Based on high-temperature compression tests and focusing on the mechanical behaviour characteristics and microstructure evolution laws during high-temperature compression, laws relating to the stra...

Austenitic steels with high manganese content exhibit various deformation mechanisms depending on their stacking fault energies. Here we present a novel approach of combining the algorithm of parti...

The deformation process of titanium with an initial crack was simulated under uniaxial tension by the molecular dynamics method. The effect of [0001], [1¯21¯0] and [21¯1¯0] orientations on ...

The mechanical behaviour of Mg–7Gd–5Y–1.2Nd–0.5Zr (wt. %) alloy with ultrafine grains was measured by split Hopkinson pressure bar method under the strain rates of 1000, 1500, and 2000 s−1 at room ...

It is important to understand the deformation mechanism of methane-hydrate specimens (MHSs) to avoid deforming the seabed during methane-hydrate production. For this purpose, discrete-element metho...

The ability to experimentally synthesise ceramic materials to incorporate nanotwinned microstructures can drastically affect the underlying deformation mechanisms and mechanics through the complex ...

Effects of thermal exposure (TE) on high cycle fatigue (HCF) behaviours in Ni-based superalloy GH4169 have been investigated in this study. GH4169 specimens were thermally exposed at 650°C ...

Tunnel excavations in rock usually cause initial stress release, which is different from the stress path in classical triaxial compression tests. To analyze the permeability variations in excavatio...

The properties of ohmic contact and thermal boundary conductance between Al and GaN have been studied extensively, but the interface structures and deformation mechanisms in the Al/GaN multilayer c...

The room-temperature tensile properties of K640S cobalt-based superalloy were investigated by tensile tests and microstructure observation. The experimental results showed that the deformation mechanism of K640S alloy is dislocation slip; that the dislocation could be decomposed into continuous stacking faults with different orientations; and that with the increase of the number of dislocations, the dislocation tangle interacts with the decomposed stacking fault to increase the tensile strength of the alloy. As the stretching proceeded further, a plurality of slip systems were activated between different grains to coordinate the deformation, and the grains were gradually plastically deformed. The stress concentration occurred at the carbide interfaces, and microcracks were formed, causing mixed crystal fracture to the alloy.

This paper presents an experimental, numerical, and analytical study on the crushing of web girders, to provide insights into the behaviour of a ship’s structure in a collision or grounding inciden...

The effect of strain rate on deformation microstructures and mechanical properties of Fe–18Cr–8Ni austenitic stainless steel was investigated at strain rates of from 10−3 to 100 s−1. The results in...

In this work, the plastic deformation mechanisms and fracture toughness of nanotwinned γ-TiAl with different twin boundary (TB) spacing are investigated by using molecular dynamics simulati...

Molecular dynamics (MD) simulations have been performed on the physically crosslinking poly(vinyl alcohol) (PVA) hydrogel to study the deformation mechanisms under uniaxial tensile conditio...

Ti-6Al-4V (Ti64) plates were subjected to rolling at 600 degrees C and 800 degrees C, respectively, for reductions up to 90% reduction in thickness. The mechanism of texture and microstructure evolution during rolling was studied in the present study. Extension twins of coherent nature were observed in the samples rolled up to 50% of reduction. The deformation was relatively inhomogeneous in the samples rolled at 600 degrees C compared to that at 800 degrees C. Visco-plastic self-consistent (VPSC) simulation showed that relative activity of pyramidal slip was higher during rolling at 800 degrees C compared to that at 600 degrees C. The average activity of slip systems per grain was less than five for the samples rolled at 600 degrees C and this might be responsible for the strain heterogeneity in the large grains. Further, twinning activity was found to be limited to a true strain of 0.5, as supported by the microstructural observation. VPSC simulation also showed the presence of contraction twins in the samples which was further supported by X-ray texture measurement. Dominant basal texture was observed in the samples irrespective of the temperature of rolling.

The present study aims to investigate the effect of grain refinement on strain hardening behaviour and fracture surface characteristics in 316LN austenitic stainless steel (ASS). The ASSs with vary...

The size effects of nano-spaced basal stacking faults (SFs) on the tensile strength and deformation mechanisms of nanocrystalline pure cobalt and magnesium have been investigated by a series of lar...

Tensile tests within a temperature range from room temperature (RT) to 1100°C were performed on a novel second-generation single-crystal superalloy DD11. The experimental results indicated that the...

We elucidate here the deformation behaviour and delamination phenomenon in a high-strength low-alloy bainitic steel, in terms of microstructure, texture and stress evolution during deformation via ...

The effects of extrusion passes on the microstructure and mechanical properties of the magnesium AZ31-Ce alloy prepared by solid-phase synthesis were studied. The deformation mechanism of Mg-Ce chips was also discussed. The alloy was characterised by optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry and an electronic universal strength tester. The results show that Mg-Ce chips are constantly crushed and deformed, and finally exhibit a fine granulated shape as the number of extrusion passes increases. The mechanical properties of the alloy markedly increase with further extrusion passes. After five passes, the tensile strength and elongation reach 311 MPa and 9.83%, respectively. The solid-phase synthesis method has the potential to prepare wrought magnesium alloys with rare earth alloying additions.

Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer, maleic anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA) copolymer with varied concentration (10-40 wt.%) using twin screw extruder. Dynamic rheological behaviour of PLA/SEBS-g-MA blends investigated a transition from liquid like behaviour to solid like behaviour in the composition range of 10-20 wt.% of SEBS-g-MA. The capillary rheometer analysis showed enhanced shear viscosity with increase in SEBS-g-MA content. At 10 wt.% of SEBS-g-MA, a maximum in the non-essential work of fracture was observed which reflects resistance to crack propagation. SEM revealed a transition in deformation mechanisms from voids, to fibrillation and cavitation.

We report the fabrication of nickel nanowires with parallel growth-twin structures (‘twin lamella’ along the wire axis) by electrochemical deposition, and demonstrate an interesting twin ‘unzipping’ phenomenon in such nanotwinned nanowires under bending. Through in situ TEM, we found that ‘unzipping’ of twin lamella was achieved by gradually increasing twin spacing along the wire axis via a layer-by-layer twin boundary migration process. Molecular dynamics simulations suggest that partial dislocation slip is responsible for activating the ‘unzipping’, with a multi-step-process involving dislocation loop initiation, expansion and partially annihilation. Our work could provide new insights into the deformation mechanisms of nanotwinned 1-D metallic nanostructures. IMPACT STATEMENT Nickel nanowires with parallel-twin structures were fabricated and demonstrated an interesting twin lamella ‘unzipping’ behavior upon flexural bending, which provides new insights into the deformation mechanisms of nanotwinned metallic materials.

The dynamic tensile behaviour and deformation mechanism of the Fe–17Mn–0.4C–0.06V twinning-induced plasticity (TWIP) steel were investigated over a wide range of strain rates from 10−4 to 1...

The subtransus deformation behaviour of Ti–10V–2Fe–3Al alloy was investigated. The flow stress curves are featured with significant flow softening, resulting from the breaking up and globularisation of lamellar α phase. The critical major axis of α phase to cause flow softening is 1 µm. Alpha phase acts as a dislocation barrier in the beginning and suppresses the recrystallisation of beta matrix. Dynamic recovery is the main restoration mode for beta matrix and alpha phase just works as a marker of it. Beta phase is dominated by strong {001} and weak {111} orientations. The Burgers relationship and variant selection are observed between α phase and β matrix in a single grain and overall samples, and the subtransus deformation does not destroy it.

To understand deformation behaviour of TiHy 600 alloy at higher temperatures, hot compression tests are performed in α region (1173 K), α + β regions (1223, 1248, and 1273 K) and β region (1323 K) at strain rates (0.001, 0.01, 0.1, 1 and 10/s) for up to 50% deformation in Gleeble 3800® thermo-mechanical simulator. Flow curve plots are drawn at each strain rates and temperatures and it is observed that dominant deformation mechanism at higher temperature 1323 K (β region) and strain rates (1 and 10/s) is dynamic recovery (DRV) whereas dynamic recrystallization (DRX) is mostly observed at lower strain rates (0.001, 0.01/s) in medium temperature range of 1223 K (α region) to 1248 K (α + β region). Hyperbolic sine law equation is used to calculate the activation energy (Q) and other material sensitive parameters (A, α and n1). The activation energies for DRX in α region and DRV in β region are obtained as 384 and 251 kJ/mol. Experimental peak stress values are compared with predicted peak stress value...

Based on the characteristics of high tenacity, low density, flexible design, the coated fabric has emerged as a promising construct for tensile test. Here, it reports the deformation mechanism of a PU-coated multi-axial warp-knitted fabric under uniaxial tensile via a digital image correlation system. Specimens produced by us are chase in three fibre-reinforced directions namely 0°, 45° and 90°, respectively. The result shows that the crease does not have an effect on the deformations in the small deformation range (strain

Equiaxed ultrafine duplex alloys γ-TiAl and α2-Ti3Al are prepared by high-energy milling and hot pressing sintering. Microstructures presenting in the mixed and sintered powders are studied by scanning electron microscopy. Structural characteristics are investigated by high-resolution electron microscopy before and after compression at 1100–1200°C. The data reveal grain sizes of 300–500 and ∼100 nm for sintered γ-TiAl and α2-Ti3Al alloys, respectively. High deformation temperatures and low strain rates lead to low peak flow stress, and at such conditions the α2/γ and α2/α2 interfaces are prone to forming dislocation structure. The studies also reveal the presence of large-angle grain boundaries for the and (0002)α2/(0002)α2 interfaces.

In the present work, the deformation mechanisms of the CoCrFeMnNi high-entropy alloy at 77 K were investigated using thermal activation analyses. The strain rate jump test was performed to estimate strain rate sensitivity and the activation volume of the alloy. Transmission electron microscopy analyses were performed to identify the evolution of twins at low temperatures. The insensitivity of activation volume to strain observed in the CoCrFeMnNi alloy at 77 K was different from the observed increase in the activation volume with strain at room temperature, which occurred due to the shearing of nanoscale inhomogeneities, such as co-clusters and short-range orders.

The dynamic response of honeycomb sandwich panels under aluminum foam projectile impact was investigated. The different configurations of panels were tested, and deformation/failure modes were obtained. Corresponding numerical simulations were also presented to investigate the energy absorption and deformation mechanism of sandwich panels. Results showed that the deformation/failure modes of sandwich panels were sensitive to the impact velocity and density of aluminum foam. When the panel was impacted by the aluminum foam projectile with the back mass of nylon, the “accelerating impact” stage can be produced and may lead to further compression and damage of the sandwich structures.

The low cycle fatigue (LCF) performance of AA6063 Al–Mg–Si alloy at under-aged (UA), peak-aged (PA) and over-aged (OA) conditions has been examined to understand the micromechanism of fatigue and the associated dynamic structural changes in this alloy. The LCF behaviour of the differently aged AA6063 alloys has been studied at strain amplitudes ranging between 0.2 and 1.0% under strain control mode. The UA state exhibits pronounced cyclic hardening unlike the PA and the OA states at strain amplitudes greater than 0.4%. The PA and the OA states show hardening only for a few cycles followed by prolonged softening. Characterisations of the micro- and the sub-structural alterations due to LCF establish that the phenomenon of dynamic precipitation results in cyclic hardening the UA alloy. The softening of PA alloy occurs due to shearing of precipitates and that in the OA alloy takes place owing to reversibility of slip by the formation and annihilation of the Orowan loops around the β (Mg2Si) precipita...

The relationship between dynamic strain ageing (DSA) and serrated flow has been investigated via alternately switching strain rates at various temperatures in a Mg–3Nd–1Zn alloy. The results reveal that serrated flow is enhanced with decreasing strain rate and increasing temperature and tends to vanish, while the DSA continually intensifies as revealed by a higher flow stress even after the serration flow disappears. A mechanism is proposed, which could explain some abnormal deformation behaviour, such as a negative strain rate sensitivity and thermal hardening.

Theoretical investigations on electronic structure, chemical bonding and mechanical properties reveal that MAB phases (CrB2)nCrAl (n = 1–3) exhibit anisotropic electrical and elastic properties, low shear deformation resistance and damage tolerance similar to MAX phases. The main contribution to the electrical conductivity is Cr 3d states and the anisotropic distribution of Cr atoms results in anisotropic conductivity. The high stiffness originates from the strong covalent B–B bonds, while the low shear deformation resistance is underpinned by metallic B–Cr bonds adjacent to Al layer. The possible slip systems are (100)[010], (010)[100], (010)[001] and (001)[010] for Cr2AlB2, (010)[001] and (001)[010] for Cr3AlB4 and Cr4AlB6.

In this paper, the microstructural evolution and deformation mechanism of the cryorolled Fe–36%Ni alloy was investigated. Deformation twinning was confirmed to be activated at the early stage of cryorolling (CR) and subsequently suppressed due to microstructure refinement. The existence of and peaks revealed that the (α′-M) phase transformation was induced during the CR process. The stress-assisted martensite and strain-induced martensite were detected to be transformed at the grain boundary and intersection of deformation twins, respectively. Owing to the co-effect of the temperature raise and mechanical stabilisation, the α′-M phase transformation was suppressed during the CR process. Therefore, the amount of the α′-M was limited in the tested alloy.

In the automotive industry, the current development trend of lightweight and low-emission vehicles requests for high-performance materials. Benefiting from an excellent balance of mechanical properties and production cost, medium-Mn steels have attracted extensive interest by materials scientists. Austenite-reverted-transformation annealing plays a vital role in stabilisation of retained austenite and grain refinement, resulting in a considerable amount of retained austenite. Localised deformation phenomenon is usually observed in the ultrafine-grained medium-Mn steels owing to the absence of strain hardening. The occurrence of transformation-induced-plasticity and/or twinning-induced-plasticity effect in austenite improves strain hardening effectively. In the current review, austenite-reverted-transformation annealing treatment routine, mechanical properties and deformation mechanisms and effect of heat treatment on microstructure and mechanical properties of medium-Mn steels are summarised.This ...

A three-dimensional crystal plasticity finite element method (3D CPFEM) modelling of a real equal channel angular pressing (ECAP) process for investigating the mechanical properties and texture evolutions of single-crystal aluminium has been developed for the first time. The challenge of modelling such a severe plastic deformation via 3D CPFEM is how to accurately predict the deformation mechanism under the complicated contact conditions between a billet and a die. The validation by comparison with experimental observations demonstrates that the developed 3D CPFEM ECAP model is able to precisely capture the deformation characteristics at the microscale. Furthermore, this research clarified the previously remaining disputes such as the microstructural formation mechanism in the deformed area and the deformation nature in the plastic deformation zone. It is also the first time to extensively discuss the orientation-dependent deformation feature of the ECAP-processed billets, including morphology, la...

An Fe–13Cr–3.4Mn–0.47C lean-alloy stainless steel was made austenitic by solution annealing at 1250°C. Tensile tests between 20 and 200°C indicated enhancement of ductility at higher temperatures. At 200°C where planar glide, manifested as deformation twinning, was the dominant deformation mechanism, a uniform tensile elongation of 102% was achieved. At 20°C where deformation-induced α′-martensitic transformation replaced deformation twinning as the dominant deformation mechanism, tensile elongation was significantly impaired. The tensile elongation contribution by the planar glide was estimated to be at least four times that of the α′-TRIP (transformation-induced plasticity) mechanism. The results indicate that inexpensive lean-alloy austenitic stainless steels exhibiting pronounced α′-formation at room temperature could become highly formable at higher temperatures.

Experimental tests on four full-scale exterior unreinforced reinforced concrete (RC) beam-column joints, representative of the existing non-conforming RC frame buildings, are carried out. The specimens have different longitudinal reinforcements (plain or deformed) and they are designed in order to be representative of two typical design practices (for gravity loads only or according to an obsolete seismic code). Different failure modes are observed, namely joint failure with or without beam yielding. The local response of the joint panel is analyzed. The different joint deformation mechanisms and their contribution to the deformability and to the energy dissipation capacity of the sub-assemblages are evaluated.

The influences of electropulse on mechanical properties of AZ31B alloy were investigated by the electro-plastic (EP) tensile tests. The results show that the flow stress decreases with the increase of the root mean square (RMS) current density, while the elongation to fracture almost remains unchanged after it reaches a certain value. The higher peak current density can lead to a more potent EP effect when the RMS current density remains approximate. The results of microstructure analysis indicate that, the electropulse can reduce the dynamic recrystallisation temperature and promote the grain boundary sliding. The inverse eutectic reaction (α + β = L) will take place at the necking zone under high electropulse, which can optimise the deformation mechanism before the liquid phase is too much.