Influence Of Recrystallization Research Articles

Hierarchical Porous Reduced Graphene Oxide/Poly(l-lactic acid) Fiber Films: The Influence of Recrystallization on Strength.

Electrospinning technology for fabricating nanofiber films and the Hummer method for synthesizing graphene oxide (GO), along with subsequent reduction, have been significantly advanced, demonstrating immense potential for large-scale industrial applications. Nanofibrous films loaded with reduced graphene oxide (rGO) have been widely explored for their applications in electromagnetic shielding, the biomedical fields, and pollutant adsorption. However, fragile mechanical performance of electrospun fibers with limited surface post-treatment methods has somewhat hindered their further industrial development. In response to this challenge, we propose a dual-regulation strategy involving post-treatment to form porous nanofiber films and the controlled flake size of rGO for surface coating during preparation. This approach aims to achieve poly(l-lactic acid) (PLLA)/rGO electrospun fibrous films with enhanced mechanical properties. It offers a roadmap for the continued application and standardized production of fibrous films loaded with rGO.

The thermal history of Permian carbonate strata reconstructed with clumped isotopes and U–Pb dating: Eastern Sichuan Basin, SW China

The lack of effective paleogeothermometers restricts the study of the thermal history of carbonate strata. Carbonate clumped isotope thermometry and in-situ U–Pb dating are appropriate for reconstructing the thermal history of carbonate strata. Herein, this study analyzed clumped isotope compositions and U–Pb ages of calcite fabrics, including micrite matrix and veins, from Permian carbonate strata in the eastern Sichuan Basin. U–Pb dating of the micrite matrix was performed to rule out the influence of recrystallization and determine the diagenetic age of the samples. Clumped isotope temperatures of the four micrite matrix samples ranged from 102 °C to 137 °C. The maximum paleotemperature derived from a solid-state reordering model was between 210 °C and 220 °C. From all four samples, three calcite veins yielded crystallization temperatures corresponding to 160 ± 10 °C, 60 ± 10 °C, and 29 ± 4 °C, as determined by clumped isotope and solid-state reordering model analyses. In-situ U–Pb dating provided corresponding crystallization ages of 159 ± 17 Ma, 256.6 ± 5.5 Ma, and 17.86 ± 0.8 Ma. The crystallization ages and temperatures of the three calcite veins align well with the thermal history of the Permian strata, indicating a high degree of accuracy. This study introduces a new strategy for reconstructing the thermal history of carbonate strata. The thermal history can be quantified using the constraints of the crystallization ages and temperatures from different stages of calcite veins or cements. This approach is suitable for determining the maturation progress of the source rock and conducting oil and gas exploration in petroliferous basins.

Influences of recrystallisation and σ phase precipitation on the mechanical properties of CoFeNiMnV high-entropy alloy

An equiatomic CoFeNiMnV high-entropy alloy with a face-centred cubic phase was cast and cold-rolled. The influence of recrystallisation and σ phase precipitation on the mechanical properties of this alloy was explored by varying the annealing temperature from 700 to 1000 °C. The results revealed that V is more effective than Cr at stabilising the σ phase. The precipitation of σ phase occurred before recrystallisation during the annealing process. The σ phase precipitation strengthening and recrystallisation softening had a combined effect on mechanical behaviour. The strength decreased with increasing annealing temperature, resulting from an increased recrystallisation percentage. Moreover, a heterogeneous structure with partial recrystallisation resulted in back stress hardening, and the precipitated σ-phase promoted crack nucleation, resulting in premature fracture.

The effect of recrystallization on the resistivity recovery of W

The influence of recrystallization on the recovery of radiation damage in tungsten (W) was investigated. Polycrystalline cold-rolled W foils were annealed in the temperature range between 1100 and 1600 °C and recrystallization and grain growth was observed. Subsequently, the specimens were irradiated with 7 MeV protons at cryogenic temperature. The induced radiation damage and its recovery during isochronal annealing treatments was monitored by in-situ measurements of the electrical resistivity. We observe that the recrystallized samples exhibit (a) a significant reduction in total defect recovery and (b) changes in characteristic features of the recovery spectra with respect to the as-received ones. These results are discussed and correlated to the effect of grain boundaries and dislocations on the radiation defect reactions.

The Influence of Recrystallization on Zinc Oxide Microstructures Synthesized with Sol–Gel Method on Scintillating Properties

Zinc oxide (ZnO) is one of the wide-bandgap semiconductors, which may be useful in a plethora of electronic, optical, piezoelectric, and scintillating applications. The following article consists in a structural and luminescence analysis of ZnO microfilms grown on a sapphire substrate with a sol–gel method. The films were annealed at different temperatures. The structures were investigated with the XRD and Raman methods, by which the influence of the substrate on the structure of the film was determined. The luminescence of films was investigated with room-temperature fluorescence, radioluminescence, and thermoluminescence.

Recrystallization-mediated crack initiation in tungsten under simultaneous high-flux hydrogen plasma loads and high-cycle transient heating

Tungsten and tungsten-based alloys are the leading material choices for the divertor plasma facing components (PFCs) in future fusion reactors. Recrystallization may occur when they undergo high heat loads, drastically modifying the predesigned grain structures and the associated desired mechanical properties. However, the influence of recrystallization on the thermal fatigue behavior of tungsten PFCs still remains unclear. In this study, ITER-grade tungsten was simultaneously exposed to a high-flux hydrogen plasma (∼5 × 1024 m−2 s−1) and high-cycle (104–105) transient heat loads in the linear plasma device Magnum-PSI. By correlating the surface temperature distribution, obtained by analyzing temperature-, wavelength-, and surface-dependent emissivity, and the surface modifications of the plasma exposed specimens, the crack initiation heat flux factor threshold was found to be ∼2 MW m−2 s0.5 (equivalently, ∼0.07 MJ m−2 for a 1 ms pulse). Based on electron backscatter diffraction analyses of cross-sections near the crack initiation sites, faster recrystallization kinetics near the surface compared to literature was observed and the surface cracks preferentially initiated at high angle grains boundaries (HAGBs). Upon recrystallization, the yield strength decreases which entails increasing cyclic plastic strains. The HAGBs fraction is increased, which constrains the transfer of plastic strains at grain boundaries. The recrystallization decreases the dislocation density, which promotes heterogeneous deformation. All these mechanisms explain the reduced crack initiation threshold of recrystallized tungsten compared to its as-received counterpart. The results provide new insights into the structural failure mechanisms in tungsten PFCs exposed to extreme fusion plasmas.

Studies on changes in the temperature field and recrystallization properties of glass fiber reinforced polypropylene composite strip winding process

The glass fiber reinforced polypropylene (GF/PP) composite ring specimens were fabricated based on the composites prepreg tape winding process. The heated winding process was simulated by ANSYS software to obtain the temperature distribution of the wound layer of the specimen. At the same time, the temperature of the wound layer was collected and stored using a temperature-controlled recorder. The temperature fields between the wound layers were found to be different significantly, and the temperature measured through experiments was generally below the simulation results, where it is especially noticeable in the fusion zone. After the recrystallization of GF/PP specimen, the maximum shear strength that the specimen can withstand was improved. The response surface method was used to test and analyze the influence of recrystallization on the mechanical properties of the specimen, Obtain optimized process parameters, heating temperature of 91 °C, pressure of the press roller is 106 N, heating time of 13 min, the highest sample obtained is 28.67Mpa. The experimental results show that the influence of recrystallization parameters on the mechanical properties of the composite specimens (from large to small) are: heating temperature, heating time, and the roller pressure.

Influence of recrystallization annealing regime on the formation of a fine-grained structure in structural steels

The analysis of the main factors affecting the reliability and safety of welded metal structures in long-term operation is carried out. The features of obtaining a fine-grained structure due to recrystallization annealing and the main factors affecting the degree of dispersion of the formed microstructure are considered. For low-carbon steel 08ps and low-alloy steel 09G2S, optimal recrystallization annealing regimes have been developed with the aim of obtaining final structures with a given degree of dispersion, typical for real building metal structures. It was found that the degree of dispersion of the obtained microstructures depends on the heating temperature, the initial structure, and the chemical composition of the steels.

Rolling asymmetry effects on recrystallization process and on properties and microstructure of annealed copper

There are number of works describing microstructural and mechanical properties of asymmetrically rolled polycrystalline metals. However, in industrial practice the rolled metals are generally annealed and recrystallized before final applications. Therefore, the influence of recrystallization on the properties of asymmetrically rolled metallic materials has to be studied. In the present paper such properties are studied for polycrystalline copper grade M1E rolled symmetrically and asymmetrically and then recrystallized. The microstructure characteristics, texture, hardness and mechanical anisotropy were examined using EBSD, X-ray diffraction and mechanical tests. The activation energy and released heat during recrystallization were determined using the differential scanning calorimetry tests.In general, the examined microstructural and mechanical properties of the recrystallized polycrystalline copper exhibit a pronounced dependence on the asymmetry ratio of the prior rolling deformation.

Study on the mechanism of chip forming and the microhardness of micro-grinding nickel-based single-crystal superalloy

Nickel-based single-crystal superalloy has no grain boundary, hence has excellent high-temperature mechanical properties and is the best option for the manufacturing of the blades of aero-engine and gas turbine. The removal mechanism of grinding traditional polycrystalline material is different from that of single-crystal material, but so far there are very few studies on grinding nickel-based single-crystal superalloy. To understand low-damage manufacturing of micro-grinding single-crystal parts, this paper first explored the chip-forming mechanism of micro-grinding nickel-based single-crystal superalloy; secondly, this paper analyzed the microstructure of micro-grinding sub-surface damage through the scanning electron microscope (SEM), then studied the microhardness on the sub-surface of grinding nickel-based single-crystal superalloy parts, and the surface-hardening phenomenon from the aspect of dislocation theory through the transmission electron microscope (TEM); finally, this paper investigated the microstructure of sub-surface recrystallization and the influence of recrystallization on the microhardness of the micro-grinding workpiece through simulating the high-temperature application environment, and the measures for controlling or inhibiting recrystallization of single-crystal parts were also discussed. The experiment results showed that the chip shape of grinding nickel-based single-crystal superalloy had the typical serrated structure due to the occurring of adiabatic shearing slippage, while the shearing slippage and the distortion took place in the sub-surface plastic deformation layer; the sawtooth degree of chips increased gradually with the spindle speed increasing; the feeding rate and grinding depth also had some effect on the sawtooth degree of the chips; the dislocation cell substructure appeared on the sub-surface of micro-grinding single-crystal superalloy, which improved the surface hardness of single-crystal parts; cellular recrystallization occurred on the sub-surface of the single-crystal parts after high-temperature treatment, which decreased the surface hardness of the workpiece and affected the service life of the parts; when the workpieces were precisely grinded using the micro-grinding tool electroplating 1000# abrasives at vs = 50,000 r/min, vw = 20 μm/s, and ap = 2 μm, followed by the annealing treatment at 760 °C for 4 h, the thickness of recrystallization layer significantly decreased, and the service life was improved. Therefore, these were good guidelines and references to the manufacturing of nickel-based single-crystal superalloy micro-workpiece.

FE Simulation of Residual Welding Stresses: Aluminium and Steel Structural Components

One of the decisive criteria in the selection of material between steel and aluminium could be the welding RS (residual stresses), which play an important role for the fatigue behavior of the structures under cycling loading. In the current paper simulations in commercial FE software ANSYS were carried out, in order to calculate the welding RS field for three different materials: structural steel S355 and the aluminum grades EN AW-6060 and EN AW-5754. In the case of EN AW-6060 influence of recrystallization on the yield strength of the HAZ (heat affected zone) was taken into consideration.

Impact of combined transient plasma/heat loads on tungsten performance below and above recrystallization temperature

The influence of recrystallization on thermal shock resistance has been identified as an issue that may influence the long term performance of ITER tungsten (W) divertor components. To investigate this issue a unique series of experiments has been performed on ITER divertor W monoblock mock-ups in three EU high heat flux facilities: GLADIS (neutral beam), JUDITH 2 (electron beam) and Magnum-PSI (plasma beam). To simulate ITER mitigated edge localised modes, heat fluxes between 0.11 and 0.6 GW m−2 were applied for Δt < 1 ms. Two different base temperatures, Tbase = 1200 °C and 1500 °C, were chosen on which ~18 000/100 000 transient events were superimposed representing several full ITER burning plasma discharges in terms of number of transients and particle fluence. An increase in roughening for both e-beam and plasma loaded surfaces was observed when loading during or after recrystallization and when loading at higher temperature. However, regarding the formation of cracks and microstructural modifications the response was different for e-beam and plasma loaded surfaces. The samples loaded in Magnum-PSI did not crack nor show any sign of recrystallization, even at Tbase = 1500 °C. This could be a dynamic hydrogen flux effect, because pre-loading of samples with hydrogen neutrals (GLADIS) or without hydrogen (e-beam JUDITH 2) did not yield this result. These results show clearly that the loading method used when investigating and qualifying the thermal shock performance of materials for ITER and future fusion reactors can play an important role. This should be properly accounted for and in fact should be the subject of further R&D.

Influence of recrystallization and subsequent aging treatment on superelastic behavior and martensitic transformation of Ni50.9Ti wires

In the present study, influence of different stages of recrystallization process and subsequent aging treatment on the superelastic properties of Ni-rich NiTi shape memory wires is investigated. Characteristics of transformation temperatures were determined using differential scanning calorimetry. Results indicate that annihilation of cold work effects after annealing results in changes on the features of DSC curves. The amount of residual strain is higher in the samples with cold work value of ε = 0.6 compared to the samples with ε = 0.4. The combination of annealing and aging treatment leads to improve in the superelastic properties. Results showed that different stages of the recrystallization process would affect the precipitation process in subsequent aging treatment.

Flow Stress Model Based on Internal Variables

In the paper a flow stress model based on internal variables is shortly presented. The multiplicative model contains three parts. In the model, the normalized dislocation density ρm was considered, as a strain function only, independently to the strain rate and the temperature. Influence of varying processing conditions (the strain rate and the temperature) is introduced as a factor. The first one is a model of so called master curve. It is an internal variable model based on dislocation density and its output value strongly depends on strain and very weakly on temperature and strain rate. The second factor introduces varying deformation conditions. Changes of flow stress do not occur instantly with the change of deformation conditions, but it requires some strain for transition. The third part considers influence of recrystallization. The results of the model parameters identification and verification in varying deformation conditions are presented in this paper.

Influence of recrystallization on high-temperature stress rupture property and fracture behavior of single crystal superalloy

A single crystal (SC) superalloy was shot peened and heat treated to induce surface recrystallization, and then the influence of surface recrystallization on the high-temperature stress rupture property and fracture behavior of the SC superalloy was investigated through high-temperature stress rupture tests. The results show that surface recrystallization greatly reduced the high-temperature stress rupture life of the SC superalloy, and the stress rupture life declined nearly linearly with the increase of the recrystallized fraction of the transverse section. At 1000°C/195MPa, the recrystallized specimens and the bare ones (without recrystallization) fractured in the same mode—microvoid coalescence fracture. The recrystallized layers cracked in the initial stage, so they nearly had no bearing capacity, which is the main cause for the remarkable decrease in the stress rupture life.

Effect of Surface Recrystallization on the Low Cycle Fatigue Behavior of Directionally Solidified Superalloy DZ4 by &lt;i&gt;In Situ&lt;/i&gt; SEM Studies

The effect of recrystallization on the low cycle fatigue life of DZ4 directionally solidified superalloy was investigated for specimens with three different recrystallized layers, which were generated by shot peening (0.1MPa, 0.3MPa and 0.5MPa respectively) and a subsequent annealing heat treatment. The fatigue life showed a decrease for recrystallized specimens with shot-peening of 0.1 MPa and 0.3 MPa, and an unusual increase for that of 0.5MPa, in comparison with the original DZ4 specimen. In-situ SEM observations were performed on the short crack growth behaviors for both original and recrystallized specimens, which revealed the fracture mechanism and the interaction with microstructure. Quantitative analysis of fatigue crack growth rates rationalized the influence of recrystallization on the low-cycle fatigue life of DZ4.

Influence of recrystallization on phase separation kinetics of oxide dispersion strengthened Fe–Cr–Al alloy

The effect of different starting microstructures on the kinetics of Fe-rich (α) and Cr-rich (α′) phase separation during aging of Fe–Cr–Al oxide dispersion strengthened (ODS) alloys has been analyzed with a combination of atom probe tomography and thermoelectric power measurements. The results revealed that the high recrystallization temperature necessary to produce a coarse grained microstructure in Fe-base ODS alloys affects the randomness of Cr-atom distributions and defect density , which consequently affect the phase separation kinetics at low annealing temperatures.

Moine Thrust zone mylonites at the Stack of Glencoul: I – microstructures, strain and influence of recrystallization on quartz crystal fabric development

Abstract Since the early descriptions published by Callaway in 1884, the gently dipping mylonites exposed along the Moine Thrust at the Stack of Glencoul have drawn generations of geologists to the northern part of the Assynt district. These mylonites, derived from Cambrian quartzites (footwall) and Moine pelites and psammites (hanging wall), have figured prominently in: a) early research into the influence of crystal plastic deformation and recrystallization on microstructural and crystal fabric evolution; b) debates on the kinematic interpretation of macro- and micro-structures and crystal fabrics; and c) debates on the tectonic significance of such kinematic data. In this paper first we briefly review the historical aspects of this research and then, using both previously published and unpublished data, document the finite strain and quartz fabric development at this classic mylonite locality. A tectonic interpretation of these data, together with quantitative estimates of flow vorticities associated with mylonite formation at the Stack of Glencoul, are presented in a companion paper by Law (2010) .

Influence of Recrystallization on the High-Temperature Properties of a Directionally Solidified Ni-Base Superalloy

The effect of recrystallization (RX) on the high-temperature tensile and creep properties of a directionally solidified (DS) Ni-base superalloy was studied. The tensile properties were not apparently influenced by RX, the depth of which is up to 18 pct of the overall gage thickness. However, an almost linear reduction of the creep rupture life was observed with the increase of the local RX depth. The failure mechanisms of the specimens were discussed based on the microstructural observations.

Influence of recrystallization on thermal shock resistance of various tungsten grades

Thermal shock resistance of various tungsten grades (different manufacturing technologies and heat treatments) was examined under plasma disruption conditions, especially in the cracking regime, i.e. below the melting threshold. The tests have been simulated with the electron beam test facility JUDITH. The comparison of the thermal shock resistance showed that sintered tungsten appeared to be better than the deformed tungsten material and clear degradation after recrystallization was found. Damage processes linked to the mechanical properties of W are discussed.