Values Of Dislocation Density Research Articles

Structural modifications of BiOBr nanoplates by electron beam irradiation

Abstract In this study, BiOBr nanoplates are synthesized through the hydrothermal method, then samples have been irradiated by an electron beam of 10 MeV energy to deliver doses of 100 kGy and 500 kGy. XRD and Raman investigations corroborated the presence of a pure phase in all nanoplate samples. The sharp and narrow peaks in XRD indicate well crystalline in nature of the samples, which decreases with increasing the electron dose as confirmed by the decay in peak intensity. Conversely, the peak position shifts at lower angle with increasing the electron dose. Structural factors including lattice parameter, dislocation density, cell volume, microstrain, as well as stacking fault have been found to change due to electron beam irradiation. We employed the Debey-Scherrer formula (D-S), Size Strain Plot method (SSP), and Halder Wagner (H-W) methods to determine the crystal size and strain of purified and irradiated BiOBr nanoplates. It has been found that the size of the crystallites increases nonlinearly as the irradiation dose increases. All three of the aforementioned calculation methods have observed this trend. Strain and dislocation density exhibited the opposite trend of crystallite size, as they decreased as the irradiation dose increased. The dislocation density, strain, and crystallite size values are nearly identical for the SSP and H-W procedures, while the D-S method exhibits values with deviation. The tetragonal structure and the Raman active mode, which we have identified as closely resembling those in other literature of this composition, are discussed in the respective section. Because of their intriguing phase strength, the synthesized nanoplates may be suitable for the degradation of organic pollutants and the separation of water through photo-electrocatalysis.

Structural and electrical characterization of nickel sulfide nanoparticles

Nickel sulfide nanoparticles were successfully synthesized through a meticulous process involving a well-mixed powder of Ni(CH3COO)2∙2H2O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is fundamental, as it forms the basis for understanding the material’s behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation Nickel sulfide nanoparticles were successfully synthesized through a careful process involving a well-mixed powder of Ni(II)2∙2H2O and Thiourea. The X-ray diffraction analysis provided insights into the structural nature of NiS, revealing its polycrystalline characteristics with a hexagonal system. This information is crucial as it forms the basis for understanding the material’s behavior and functionality in various applications. Determining the average values of mean crystallite size, microstrain, and dislocation density for the (100) plane (32.62 nm, 0.000296, and 0.000939 nm-2, respectively) contributes to a comprehensive understanding of the material’s structural features. The photoluminescence spectrum of NiS in the visible region revealed split peaks at 405.8 and 428.25 nm, shedding light on the radiative recombination process between electrons and holes. The confirmation of thermal stability through a thermogravimetry diagram is essential for applications in elevated temperature environments, ensuring the material’s reliability under varying conditions. Analyzing the stoichiometry of NiS using energy dispersive spectroscopy attached to transmission electron microscopy provides insights into the material’s composition. Cyclic voltammetry results indicating a diffusion coefficient greater than that of NiS added to carbon hold significance for electrochemical applications. The unique characteristic peaks observed in cyclic voltammetry for fuel cell applications suggest the potential use of NiS in energy conversion technologies, broadening its scope of application. The confirmation of NiS’s ability to elucidate the physical and electronic properties of electrochemical systems through electrochemical impedance spectroscopy underlines its importance as a versatile material in various research and practical domains.

Change in the qualitative composition of non-metallic mineral raw materials as a result of blasting operations

Purpose. The research purpose is to study the change in the qualitative composition of granite before and after blasting operations to determine its compliance with the criteria of marketable products. Methods. X-ray phase and X-ray structural research methods are used to study changes in the mineral composition of granites before and after blasting operations. To separate magnetic and non-magnetic fractions of the selected granite samples, a three-roller RST magnetic separator is used. X-ray phase research is conducted using a DRON-3 diffractometer. Additionally, an analysis of the unit cell dimensions of the quartz crystal lattice was conducted, and the dislocation density along the corresponding crystallographic planes was studied. Findings. It has been determined that after blasting operations, granite mass is redistributed from coarse fractions of 1-20 mm to small fractions of 0-1 mm with an increase in the latter by 4.2%. It has been found that the biotite content decrea-ses naturally and consistently, and the quartz content increases correspondingly in products in the following series: magnetic separator drum (90%, 2%) → lower roller (72%, 14%) → upper roller (55%, 31%) → non-magnetic product (48%, 34%) before blasting operations. Therefore, despite significant differences in the magnetic favorability of these two mineral phases, they are present in all magnetic separation products (with the exception of quartz in the non-magnetic product): magnetic separator drum → lower roller → upper roller. Originality. It has been established that along the crystallographic directions 101 and 211, the maximum gradient of dislocation density increase in the quartz crystal lattice in granite samples before blasting operations is observed during the transition from the lower roller product to the upper roller product, amounting to 1.55·1010 and 6.63·1010 cm-2, respectively. After blasting operations, in granite samples along the same directions, the maximum gradient of dislocation density increase is observed between the upper roller product and the non-magnetic product, amounting to 3.01·1010 and 4.67·1010cm-2. As a result of the thermodynamic impact of blasting operations, the weighted average dislocation density value along crystallographic planes 101 and 211 in the quartz crystal lattice increases by 47.21 and 25.72%, respectively. Practical implications. Understanding the quality characteristics of marketable products after blasting operations will contribute to optimizing the stages of further processing of non-metallic mineral raw materials (two-, three- or four-stage crushing) and expanding the scope of granite applications. This increases its competitiveness in the building materials market by reducing the costs for additional processing with a reduction in the labor intensity of the process.

The influence of gamma radiation on the structure and morphology of AgNWs/GO nanocomposites

In this study, AgNWs/GO nanocomposites were prepared by mechanically mixing graphene oxide (GO) synthesized using a modified Hummers' method and silver nanowires (AgNWs) synthesized using a modified polyol method. These nanocomposites were subjected to gamma radiation at three different doses (8, 25, and 50 kGy). Modification of materials by gamma radiation is a very important issue in materials science. The effects of gamma radiation on the structure of the nanocomposites were investigated through X-Ray diffraction (XRD) analyses. Changes in morphology depending on the radiation dose were examined using transmission electron microscope (TEM) images. Elemental analysis was performed before and after irradiation. For GO irradiated at a dose of 25 kGy, the strain and dislocation density values reached their highest levels (ε = 0.065 and σ = 3.33 × 1012 cm−2). Following gamma radiation exposure, the strain and dislocation density of AgNWs showed a non-linear decrease compared to the initial sample. The highest values for both strain and dislocation density were recorded at the 0 kGy dose (ε = 0.0064 and σ = 0.0036 × 1012cm−2). Elemental analysis (EDS) indicated that reduction processes occurred depending on the radiation dose, with the highest reduction observed in the sample irradiated at 25 kGy. Studies indicate that gamma radiation can modify the structural and physical properties of the AgNWs/GO nanocomposite.

Structural Changes in High-Entropy Alloys CoCrFeNi and CoCrFeMnNi, Irradiated by He Ions at a Temperature of 700 °C.

High-entropy alloys (HEA) are promising structural materials that will successfully resist high-temperature irradiation with helium ions and radiation-induced swelling in new generations of nuclear reactors. In this paper, changes in the elemental and phase composition, surface morphology, and structure of CoCrFeNi and CoCrFeMnNi HEAs irradiated with He2+ ions at a temperature of 700 °C were studied. Structural studies were mainly conducted using the X-ray diffraction method. The formation of a porous surface structure with many microchannels (open blisters) was observed. The average diameter of the blisters in CoCrFeMnNi is around 1.3 times smaller than in CoCrFeNi. It was shown that HEAs' elemental and phase compositions are stable under high-temperature irradiation. It was revealed that, in the region of the peak of implanted helium, high-temperature irradiation leads to the growth of tensile macrostresses in CoCrFeNi by 3.6 times and the formation of compressive macrostresses (-143 MPa) in CoCrFeMnNi; microstresses in the HEAs increase by 2.4 times; and the dislocation density value increases by 4.3 and 7.5 times for CoCrFeNi and CoCrFeMnNi, respectively. The formation of compressive macrostresses and a higher value of dislocation density indicate that the CoCrFeMnNi HEA tends to have greater radiation resistance compared to CoCrFeNi.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

Development of eutectics of pioglitazone with citric acid and its effect on crystallite properties and dissolution.

Eutectics of pioglitazone were developed using citric acid (CA) as the co-former, and the effect on crystallite properties and dissolution has correspondingly been studied. Pioglitazone-citric acid eutectics (PC1, PC2, PC3, and PC4) in different molar ratios (3:1, 3:2, 1:1, and 3:4 respectively) were prepared by simple solvent evaporation method. Difference in dislocation density and strain value of the eutectics were observed, and the maximum strain value of PC1 might be due to the highest deformation activity compared to PC2, PC3, and PC4. Carbonyl-thiazolidine or carboxyl-pyridine weak bond formation might be the reason of producing eutectics of PGZ-CA rather than cocrystal with a docking score of - 2.2 Kcal/M. Likewise, lowest particle size was found with PC1 rather than that of pure PGZ and other eutectics. PC1 demonstrated highest dissolution of drug (68 %) rather than other eutectics (54 to 61 %) and PGZ (44 %) after 360 min.

Gradient microstructures and mechanical properties of WAAMed and aged Al–Cu alloy after laser shock peening

The integration of wire-arc additive manufacture (WAAM) and laser shock peening (LSP) facilitated the study of the gradient microstructure in T6-treated WAAM Al–Cu alloy and the synergistic strengthening mechanisms involving the precipitation phase and LSP parameters. The results indicate that pore closures, increases in kernel average misorientation (KAM), and low angle grain boundary (LAGB) are positively associated with LSP energy density. Residual stress positively correlates with LSP energy density and inversely with spot diameter, where larger spots exacerbate non-uniformity. The values of dislocation density, microhardness and residual stress of the post-LSP specimen gradually increase with the increase of depth, and reach the maximum value at ~100 μm. As the depth continues to increase, the value begins to decrease gradually. Dislocation accumulation near grain boundaries, interacting with θ’-Al2Cu, contributes to strength enhancement. The main strengthening mechanisms enhanced by LSP involve creating a gradient microstructure through significant plastic deformation, pore closure, and the presence of high-density dislocations. Post-T6 treatment, θ’-Al2Cu significantly restricts dislocation slip, pins dislocations, and encourages the emergence of new dislocation sources, thereby enhancing the strengthening effect and stability induced by LSP.

Investigation of the impacts of artificial ageing, re-ageing and cryogenic cycles on multiplex second phase precipitation and life-time prediction in 7075 alloy

In this study, artificial ageing, re-ageing and multiple levels of cryogenic treatments were practiced on 7075 aluminium alloy. Microstructural changes in the material as a result of the final cryogenic cycles were characterized by SEM and TEM, and the resulting phases with successive upsurge stages of nucleation sites were observed. Throughout crystallographic and X-ray analyses; dislocation densities, strain values of the planes, texture coefficient and plane orientations were determined. Micro-hardness measurements were also carried out to mechanically support the data attained from these characterization methods. According to the results, dislocation density and hardness values particularly after −40 °C cryogenic treatment, achieved the highest value. Heating rate and activation energy-based phase life time predictions against temperature, together with nucleation and growth rates of precipitates were evaluated by thermal analyses. Life time calculations pointed out that the −40 °C was the critical point of sub-zero progression where, the longest useful life expectancy at temperatures of between 80 °C and 300 °C could be reached out meticulously.

Microhardness and Microstructure of Aluminium Alloy 5052 by High-Pressure Torsion Process and Subsequent Annealing

The grain refinement by high-pressure torsion (HPT) process and high-temperature stability have been studied in a commercial non-heat-treated aluminium alloy, 5052. The HPT process was conducted on 10 mm disks of the alloys at room temperature with an applied pressure of 6 GPa for 5 and 10 turns with a rotation speed of 1 rpm. The HPT processing leads to microstructural refinement with an average grain size of ~188 nm and ~156 nm for 5 turns and 10 turns with an increased value of dislocation density. The Vickers microhardness test was performed at 100 gf for a duration of 15 s. It was found that the hardness increased from the onset of straining and saturated at approximately 165 Hv after processing at both 5 and 10 turns. The samples were then annealed at high temperatures. The study demonstrated that annealing at 200 °C for 1 h reduced the hardness by 30% in both samples and enlarged the gain sizes to 226 nm. The results indicated that the rate of hardness decrease is faster in 10 turns compared with 5 turns thus explaining the higher kinetic annihilation phenomenon observed in higher straining in 10 turns due to the higher stored energy in the grains.

Thickness effects on the physical characterization of nanostructured CuO thin films for hydrogen gas sensor

In these studies, radio frequency (RF) magnetron sputtering was used to produce nanostructured CuO thin films on glass bases with different thicknesses of (250, 300, and 350 nm). X-ray diffraction (XRD) analysis of these films revealed a polycrystalline structure with a preferred peak along the (111) plane. The Scherrer formula was used to compute the grain size. It was found that the average grain sizes are 10.78 nm, 11.36 nm, and 11.84 nm for film thicknesses of 250, 3000, and 300 nm, respectively, while the dislocation density and strain values decline. The surface roughness decreased from 9.30 nm to 4.71 nm as the thickness increased, according to atomic force microscopy (AFM) data. As the thickness of the film grew, the root mean square (RMS) roughness likewise decreased from 9.18 nm to 4.29 nm. The homogenous, semi-spherical structure comprises uniformly distributed particles, as demonstrated by SEM images. The optical properties of the grown films showed that the absorption coefficient considerably increased with film thickness. Transmittance, band gap, refractive index, and extinction coefficient all decrease with increasing film thickness. The hydrogen gas measurements, indicated a reduction in sensitivity as the thickness and gas concentration increased at 30°C.

Assessment of phenomenological models for Indentation Size Effect (ISE) through physically based dislocation density evolution

The depth dependent hardness, referred to as indentation size effect (ISE) has gained considerable attention. ISE is attributed to the strain gradient caused by the inhomogeneous strain distribution beneath the indenter tip. The depth dependence of hardness is phenomenologically accounted using an appropriate length scale parameter. The Unified model is one such model that is built on Nix–Gao’s model and focuses on integrating various length scale parameters resulting from both microstructural and geometrical effects. One aspect of the current work is to assess the applicability of the Unified model to a material like bulk Nickel with a history of cold work. Also, the physics of ISE in metals can be related to the dislocation mean free path influenced by strengthening mechanisms. Past attempts are scarce to quantify the ISE through the microstructure variables. In the present work, an attempt has been made to simulate the nanoindentation test using a dislocation density based constitutive model. The objective of this study is to establish a correlation between the equivalent plastic strain resulting from deep depth indentation (which does not exhibit a size effect) and an equivalent dislocation density. The dislocation density here serves as a state variable that describes the microstructure-dependent mechanical behaviour. The modified KME, a dislocation density-based model, is incorporated as a user subroutine in a commercial finite element solver. It has been proven to accurately predict the indentation behaviour at substantially large depths, which aligns well with the predictions of the Unified model or experimental observations. The good correlation between the value of effective dislocation density and equivalent plastic strain in the plastic zone underneath the indenter assures to extend the use of dislocation density as a state variable to predict ISE.

Influence of deposition temperature on the defect mediated persistence photo-conducting behaviour of spray coated Zn0.96Nd0.04O thin films

The incorporation of Neodymium into ZnO lattice enhances the photo conducting property of the deposited films which are strongly dependent on preparation conditions. Hence, the comprehensive work carried out to understand the influence of deposition temperature (300 °C–500 °C) on the persistence photoconductivity of Zn0.96Nd0.04O films deposited on glass substrates using spray pyrolysis method. The maximum crystallite size of ∼16.3 nm with minimum dislocation density and strain values were noticed for the films deposited at 450 °C. The mixed fibrous -granular morphology was noticed in the deposited films. The maximum transparency above 90 % in the visible region and an increased bandgap of 3.42 eV was observed in the films deposited at 450 °C. The percentage of defects were calculated using the area under the curve of photoluminescence spectra. The charge carrier density of 1.7 × 1017 cm−3, mobility of 62.8 cm2/Vs and lesser resistivity of 1.3 × 102 Ω cm were noted for the films deposited at 450 °C. Under the illumination of UV light, the photocurrent of Zn0.96Nd0.04O films deposited at 450 °C increased by four orders. The persistence in the photo resistance was due to the presence of Zn and O related defects, which acts as trap centres. The variation of photo resistance with time indicates the films deposited at 450 °C has faster photo response due to the faster electron – hole recombination process. The maximum photocurrent at 360 nm was noted for the films synthesized at 450 °C due to improved crystallinity with stoichiometry nature of the films. Hence, the Zn0.96Nd0.04O films deposited at 450 °C suitable for light dependent resistor and fixed wavelength UV photodetector applications.

Investigation of the effect of ball-burnishing treatment applied to Al 7075-T6 alloy on mechanical and crystallographic properties

ABSTRACT In this study, the mechanical, microstructural, and crystallographic effects of ball-burnishing applied to Al 7075-T6 alloy at 0.15–0.30 mm penetration depth, 0.15–0.30–0.60 mm/rev changing feed rates and 100–200 rpm range were investigated. After the ball-burnishing processes were carried out in different parameters, surface roughness measurements were applied to determine the surface qualities, and hardness and impact energy tests were applied to characterise the mechanical properties. Dislocation density and texture coefficient values were calculated by determining the crystallographic properties using X-ray diffraction. It has been determined that the ball-burnishing process directly affects the surface roughness, depending on the increasing rotational speed and feed rate. As a result of microstructural investigations, the average grain size decreased with increasing amount of deformation on the sample surface. At 200 rpm ball-burnishing parameter, the surface hardness of the sample increased by approximately 41% compared to the initial state and was measured as 265 HV2. It was determined that the ball-burnishing process did not positively affect the impact of the toughness of the alloy. The reason for this is that the roughness and scratches on the surface caused by the ball-burnishing process have a notch effect, increasing the crack formation and propagation speed.

Annealing effect on physical characterisation and sensing properties of nanostructered AgO thin films

Thermal evaporation (TE)was employed to create thin coatings of AgO on glass substrates. The post-annealing temperatures for the deposited films were (100, 150, and 200), respectively. The XRD data demonstrate that when annealing temperature climbed from 100°C to 200°C, the intensity of (100) plane strengthened. Regardless of the temperatures used for post-annealing, the XRD spectra show that the films are polycrystalline and have a cubic structure. The average grain size was 15.39 nm, 16.30 nm, and 17.68 nm for the intended films. When the annealed temperature rises, the dislocation density and strain value decrease. The root mean square (RMS) roughness measured via AFM images decreased from 7.33 nm to 3.64 nm. Due to annealing at 200°C, the average particle size behaved similarly and reduced from 76.9 nm to 46.5 nm. The surface roughness exhibited the same behavior and dropped from 8.77 nm to 4.46 nm at 200 o C. The sample annealed at 200°C had the highest absorbance values, whereas the sample annealed at 100°C had the highest transmittance values. As the film annealing increased, the absorption coefficient rose somewhat. The bandgap of AgO thin films falls from 1.59 eV to 1.44 eV with the rise of annealing. In contrast, the transmittance, refractive index, and Extinction coefficient also lower as the temperature rises. Sensitivity measurements indicated a reduction in sensitivity as the annealing temperature and gas concentration increased.

Selective Epitaxy of Germanium on silicon for the fabrication of CMOS compatible short-wavelength infrared photodetectors

Here we present the selective epitaxial growth of Ge on Si using reduced pressure chemical vapor deposition on SiO2/Si solid masks realized on 200 mm Si wafers, aiming at manufacturing integrated visible/short-wavelength infrared photodetectors. By a suitable choice of the reactants and of the process conditions, we demonstrated highly selective and pattern-independent growth of Ge microstructure featuring high crystalline quality. The Ge “patches” show a distinct faceting, with a flat top (001) facet and low energy facets such as e.g. {113} and {103} at their sidewalls, independently on their size. Interdiffusion of Si in to the Ge microcrystals is limited to an extension of ∼20 nm from the heterointerface. The Ge patches resulted to be plastically relaxed with threading dislocation density values better or on par than those observed in continuous two-dimensional Ge/Si epilayer in the low 107 cm−2 range. A residual tensile strain was observed for patches with size >10 μm, due to elastic thermal strain accumulation, as confirmed by μ-Raman spectroscopy and μ-photoluminescence characterization. Polarization-dependent Raman mapping highlights the strain distribution associated to the tridimensional shape. On this material, Ge photodiodes were fabricated and characterized, showing promising optoelectronic performances.

Dislocation density-based fatigue approach for structural steel details

Global approaches have been the main procedure for designing structural details and components under fatigue loading. This procedure is easy to apply but it disregards not only the effect of the material type but also the influence of the geometry. On the other hand, local approaches rely on the specific local parameters that can be assessed for each type of material and detail geometry. The parameters derived from low cycle fatigue (LCF) tests are the most common damage parameters used to predict fatigue life and establish fatigue design approaches. Recently, Huffman proposed a fatigue damage model based on strain energy density and dislocation density of the material. In this regard, two structural steels were selected to perform a metallographic and mechanical characterization aiming to determine fatigue life parameters and dislocation density. The fatigue behavior of these materials was evaluated using strain-Morrow, SWT, and strain-Huffman parameters, and the dislocation density values obtained by XRD were analyzed. Additionally, experimental results from fatigue tests on structural details (plate with hole) were compared with fatigue life predictions based on each local model. It was found that the Huffman model based on dislocation density is a reliable approach to predict the fatigue life of structural steel details.

Defect structure of high-resistance CdTe:Cl single crystals and MoOx/CdTe:Cl/MoOx heterostructures according to the data of high-resolution X-ray diffractometry

Clorine doped CdTe single crystals (CdTe:Cl) were grown by the traveling heater method. MoO x /CdTe:Cl/MoO x films were deposited using the reactive magnetron sputtering technique. The defect structure of the obtained single crystals and heterostructures was investigated using high-resolution X-ray diffractometry. The optimized models of dislocation systems in the CdTe:Cl single crystals were constructed based on the Thompson tetrahedron. The distribution of the intensity of diffracted X-rays as a function of reciprocal space coordinates and rocking curves was analyzed using the kinematic theory of X-ray scattering in real crystals. The experimental and theoretically predicted values of the helical dislocation densities in the CdTe:Cl and MoO x /CdTe:Cl crystals with perfect and mosaic structures were compared. Two-fold increase in the dislocation concentration in the MoO x /CdTe:Cl heterostructures as a result of compression deformations of the CdTe:Cl crystal lattice was found. The ~0.1 μm thick transition deformed layer at the boundary between the MoO x film and CdTe:Cl single crystal significantly affects the electrical and spectroscopic properties of the obtained systems as the materials for γ-radiation detection.

Effects of Pre-Strain and Tempering on Mechanical Properties in High-Strength Martensitic Steels

Effects of pre-strain and tempering on mechanical properties in high-strength martensitic steels were investigated. In this study, strain tempering (ST) and quenching and tempering (QT) martensitic steels were prepared, and their mechanical properties were studied. In the tensile tests at the deformation temperatures between 296 and 573 K, the ST sample increased both of tensile strength (TS) and uniform elongation (U.El) from 473 to 523 K whereas the QT sample increased U.El with little change of TS. From the in situ neutron diffraction experiments, stress partitioning to the bcc phase increased with an increase in the deformation temperature from 296 to 523 K. The difference of phase stress between the bcc and cementite phases decreased with increasing the temperature because of a decrease in the cementite strength. In the ST sample, Pre-straining of 0.5% increased YS at 296 K with slight work hardening. The initial value of dislocation density (ρ) decreased at 523 K but ρ increased significantly after yielding, leading to better combination of TS and U.El. The combinations of pre-strain, tempering, and deformation temperatures have changed ρ before deformation and the increase of ρ after yielding of the martensitic steels.

316L-Si Austenitic Stainless Steel Elaborated by Additive Manufacturing Process: Porosity and Dislocation Density Estimation

This investigation estimated porosity and dislocation density in austenitic stainless steel 316LSi thin walls fabricated by Cold Metal Transfer Wire and Arc Additive Manufacturing (CMT-WAAM). Porosity density was calculated using ImageJ software. MAUD software (Materials Analysis Using Diffraction) was used to analyze the microstructural parameters and dislocation density. The density of pores and microstructural parameters of 316LSi alloy exhibit typical values of AM conditions. The porosity values oscillate between 2.80 to 3.48 %. The obtained dislocation density values are 5.0 e+12, 4.3 e+12, and 3.2 e+12 for 2.4 e+12 m-2 for 70, 80, 90, and 140 A current source, respectively. In 316LSi thin walls, the increases in the current input in CMT-WAAM are accompanied by the very lowest decrease in the dislocation density state.