Phase Particle Distribution Research Articles

Optimization of microstructure and mechanical properties of 7075 aluminum alloy by equal channel angular pressing technology

Abstract The equal channel angular pressing technology, as an effective technique for modifying the surface of a material, has had a significant impact on the microstructure and mechanical properties of the 7075 aluminum alloy. The study achieved the refinement of 7075 aluminum alloy grains and the homogenization of the second phase particle distribution through equal channel angular pressing technology, thereby significantly improving the strength and plasticity of the material. Through orthogonal experimental design, the effects of extrusion angle, extrusion speed, and remelting temperature on material properties were studied. The results showed that appropriate ECAP parameters could effectively regulate the microstructure of 7075 aluminum alloy, thereby optimizing its mechanical properties. Especially in the analysis of equivalent strain rate, when the extrusion angle was 50°, the position of the maximum equivalent strain rate at the forefront point remained unchanged, but the equivalent strain rate decreased to 0.107-1. In the aging hardness analysis, when the number of equal channel angular pressing passes was 3, the aging hardness of G group 7075 aluminum alloy increased to 195HV in the first 5 minutes. The equal channel angular pressing technology can optimize the internal structure of 7075 aluminum alloy and improve the material's plasticity and mechanical properties. The research provides important technical support for the application of 7075 aluminum alloy in high-end equipment manufacturing.

Micromechanical and microstructure evolution of leaded (SnPb) and lead-free (SAC305 and SnCu) mixed solder joints during isothermal aging

This paper studies how isothermal aging affects the micromechanical and structural properties of mixed solder joints made of 60Sn-40Pb (SnPb) with Sn-3.0Ag-0.5Cu (SAC305) and SnPb with Sn-0.7Cu (SnCu). The nanoindentation test was done to measure the micromechanical properties of SnPb/SAC305 and SnPb/SnCu mixed solder joints. These properties are hardness, reduced modulus, and stress exponent. Scanning electron microscopy (SEM) was used to look at the microstructure of a cross-section of mixed solder joints. The micrographs that were taken were then examined with open-source image processing software called ImageJ. It was found that the rate and distribution of intermetallic compound (IMC) formation and the reduction of Sn-rich phase grain size affect how the hardness and stress exponent values of mixed solder joints change after 1000 h of high temperature storage (HTS). ImageJ analysis shows that the Pb-rich phase particle count and distribution can be used to figure out how mixed solder joints respond to indentation creep and how that relates to isothermal aging. Using ImageJ, it’s clear that the indentation creep behavior of the GBS mechanism of an as soldered SnPb/SnCu mixed solder joint is caused by the highest number and size of Pb-rich phase particles that are not well distributed across the dendritic area of Sn-rich phase grain boundaries.

Corrosion property of Al alloys subjected to surface severe plastic deformation: a review

Purpose This study aims to discuss the influences of surface severe plastic deformation (S2PD) on the electrochemical corrosion, pitting corrosion, intergranular corrosion, stress corrosion cracking of aluminum (Al) alloys and attempt to correlate the microstructural/compositional changes with the performances. Design/methodology/approach This study provides a novel gradient design of structure/composition caused by S2PD for the purpose of enhancing Al alloys’ corrosion resistance. Findings S2PD has a significant effect on corrosion behavior of Al alloys through tuning the grain size, residual stress, composition, grain boundary phase and second phase particle distribution. Originality/value Although Al alloys are known to form a protective Al2O3 film, corrosion is a major challenge for the longevity of Al structures across numerous industries, especially for the infrastructures made of high-strength Al alloys. Traditional strategies of improving corrosion resistance of Al alloys heavily relied on alloying and coatings. In this review, gradient design of structure/composition caused by S2PD provides a novel strategy for corrosion protection of Al alloys, especially in the enhancement of localized corrosion resistance.

Numerical Simulation of Flow Characteristics in Circulating Fluidized Bed Boiler

Considering the different particle sizes in the circulating fluidized bed boiler furnace, the binary-component method is used to analyze the flow characteristics in the circulating fluidized bed boiler furnace. The particle dynamics principle is used to solve the gas-solid two-phase mass equation, momentum equation and turbulence equation using the two-fluid model. The model uses more mature boiler design drawings, reproduces the flow characteristics of particles in the furnace, obtains the shape of the lower bubbling bed and the fast upper bed, and analyses the gas phase velocity and particle distribution in the furnace under the design parameters.

Effect of radial-shear rolling on particle’s morphology and mechanical properties of AA7075 alloy

Effect of radial shear rolling on the morphology of intermetallic particles, and the mechanical properties of 7075 alloy at different processing temperatures and heat treatment after deformation was investigated. The results were consistent with data on metallographic investigation of phase particle shape, counts, and distribution. It was found that the formation, quantitative distribution, and circularity of particles at the surface and in the centre of the bar depended on the processing temperature and temperature gradient between surface and centre and were defined with a scheme of stresses in the deformation zone. The values of strength properties for all bars obtained by RSR depended on the processing regimes, while plasticity (elongation to failure δ = 14%–20%) increased with the growth of processing temperature. Article highlights Radial shear rolling makes it possible to obtain aluminium alloy bars with a gradient structure and a combination of high strength and ductility. The influence of the RSR method is reflected in the nature of the distribution of dispersive particles in the matrix of alloy. Mechanical properties of bars subjected to the RSR method depend on the initial processing regimes, while the level of plasticity increases with the growth of processing temperature.

The Spectroscopic and Antimicrobial Yield of Sol-Gel Derived Zinc Copper Silicate/E102 Nanoclusters

The structural and optical properties of 30 ZnO: 50 SiO2: (20-x) CuO (ZSC) loaded with E102 (tartrazine dye) (where x = 0.02, 0.05, 0.07 wt.%) nanoclusters have been explored. These nanoclusters were synthesized by a sol-gel route followed by a very controlled crystallization process at 500 °C. The phase formation, structural modification, and particle distribution behavior of these nanoclusters have been studied using XRD and TEM analysis to monitor the domestic environment for ZCS-E102. The optical transmission and reflection properties of nanoclusters in the UV–Vis-NIR range were studied for the present nanoclusters from which the optical absorption was calculated. Tauc method is employed to estimate the type and value of energy needed to gap transition from absorption data. The direct and indirect gap shows decreased energy need for its transition by E102 concentration increase. The antimicrobial potentials of four synthesized nanoclusters were performed against some pathogenic microbes. The toxicity performance of all studied nanoclusters is measured. Results revealed that ZSC-0.07E102 is showed an effective antimicrobial action against four tested pathogenic microbes in terms of excellent inhibitory effect and biocompatibility show noticeable potential in the antimicrobial application. Therefore, this proficient nanomaterial is a promising choice for biomedical purposes.

Hydrogen embrittlement of bulk W-0.5 wt% ZrC alloy induced by annealing in hydrogen atmosphere

Annealing of a tungsten alloy containing 0.5 wt% zirconium carbide (WZC) in hydrogen atmosphere induced hydrogen embrittlement, which was investigated by exploring the evolution of the tungsten grain size and orientation, the second phase particles distribution, and the tensile properties of the hydrogen-containing and hydrogen-free WZC samples. Thermal desorption spectroscopy used to determine the hydrogen retention revealed a broad hydrogen desorption peak at 1000 – 1300 K, whose hydrogen origin was attributed to the trapping sites in the non-stoichiometric ZrCx of the WZC samples after annealing in hydrogen atmosphere at 1300 °C. Hydrogen retention resulted in the degradation of mechanical properties including strength and ductility and in the deterioration of the ductile-to-brittle-transition behavior. The results emphasize the importance of the atmosphere choice for annealing tungsten materials to avoid hydrogen embrittlement and to ensure good mechanical properties.

Investigation of the Rheokinetic Properties and Penetration Depth of Aluminosilicate Adhesive in Pine Wood

Practical work and is devoted to the study of the rheological and deformative properties of Geofip aluminosilicate glue, obtained on the basis of an alkaline aluminosilicate binder composition Na2O Al2O3×6SiO2×20H2O, modified with 5% Cr2O3, when gluing wooden trusses in the field. The rheological and deformative properties of an aluminosilicate adhesive based on an alkaline aluminosilicate binder composition of Na2O×Al2O3×6SiO2×20H2O modified with 5% Cr2O3 have been investigated. It is noted that the dynamic viscosity of the adhesive slurry in the speed range from 0.1 to 0.8 RPM varies from 147600 to 144600 cP, and the average plastic viscosity in the same speed range is 87.39 cP. It was found that at shear rates from 0.021 to 0.168 1/s, an increase in shear force from 31 to 242.9 dyne/cm2 is observed due to the stabilization and uniformity of the dispersion phase particle distribution in the dispersion medium of the adhesive. It is shown that the aluminosilicate adhesive at a surface tension value of 88.1 mN/m is characterized by coefficients of wetting (s = 0.648) and fluidity (f = -62.02 mN/m), which ensures the uniformity of its application to the pine substrate. The average thickness of the adhesive layer was 1.25 mm, and the average depth of penetration of the aluminosilicate adhesive into the wood substrate, respectively, 0.12 mm. The destruction of the adhesive seam occurred at shear stresses of 515 MPa. The relative shear deformations were 162.5×10-5 mm.

Study on corrosion fatigue properties and fracture characteristics of 7075 aluminum alloy FSW joint

Taking 7075-T6 aluminum alloy friction stir welding joint as the research object, the microstructure, 3.5 wt % NaCl solution corrosion fatigue life and corrosion fatigue fracture characteristics were studied, and the corrosion fatigue performance and fracture process of 7075 aluminum alloy friction stir welding joint were analyzed. The results showed that: the S-N curve equation of corrosion fatigue of 7075-T6 aluminum alloy friction stir welded joint is lgN=5.845-0.014S, With the increasing of stress amplitude, the corrosion fatigue life decreased greatly. The corrosion fatigue crack originated in the thermal affected zone of the joint, gradually expanded and finally broke in the welded core zone of the joint. There were multiple crack sources in the corrosion fatigue fracture, and with the influence of stress concentration, the crack source originated in the corrosion pit. The high stress aggravated the corrosion damage of the corner part of the sample, led to more serious corrosion than that of the plane position. Obvious intergranular fracture and fatigue striation appeared in the crack growth zone. Under the combined action of corrosive medium and alternating load, the crack growth zone suffered the most serious corrosion, and the anodic dissolution occurred at the grain boundary, resulting in the morphology characteristics of “rock candy” and “ant nest”. Instantaneous fault zone was brittle fault,and there were a lot of cleavage steps and secondary cracks in this zone, the pore morphology appeared in the second phase particle distribution region.

Model of Dispersed Phase Particle Distribution in a Composite Electrolytic Coating

A model is proposed to evaluate distribution of dispersed phase particles in a composite metal coating. This model is based on calculation of degree of surface occupation by particles and their distribution in volume. Effective parameters applied for electrolytic composites evaluation at the microscale level were formulated, and method for the parameters evaluation was set out. It was shown that density of distribution and portion of particles with certain size in a coating depend on electrodeposition modes. Generation of higher-fine crystalline close-packed structures of coatings in conditions of pulse relative duration increase from 2 to 50 and unchanged current frequency 50 Hz is caused by both increase of oversaturation at the crystallization front that results in higher non-equilibrium process of crystallization and also by passivation effect of UDD particles on the surface which is formed. Non-equilibrium conditions of crystallization give rise to more intensive penetration of disperse phase particles with smaller size (~ 0.25–1 μm) into growing coating, decrease of microlayers thickness from 4 to 2 μm and increase of UDD particles concentration from 1.43 to 2.47 mas.%.

Development of texture and grain size during extrusion of ZA63 alloy containing stable quasicrystalline i-phase and its effect on tensile and compression strength

We have focused on dispersion of quasicrystalline i-phase in a “Rare Earth-free” magnesium alloy Mg–6Zn–3Al (ZA63). The alloy was chill-cast to produce orthorhombic φ phase interdendritically and quasicrystalline i-phase particles with strong pinning effect at grain boundaries, giving the boundaries a very curved shape. The cast alloy was subjected to a two-step direct extrusion process to study phase (particle) distribution, grain structure, microtexture and related parameters using a host of techniques associated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the resulting mechanical properties. The first extrusion (at 563 K) with a small extrusion ratio of 6.25:1 produced a dispersion of φ phase along the extrusion direction and i-phase decorating the boundaries of grains of size of about 30 μm with a mild basal texture. The second extrusion (at 483 K) with an extrusion ratio of 25:1 reduced the average grain size to ∼2μm, with comparable yield strength 287.0 ± 4.1 MPa in tension and 299.0 MPa in compression (elongations ∼ 21%). The i-phase was found to be stable by differential scanning calorimetry (DSC) and the φ phase appeared to transform to the i-phase.

How to Choose the Best Analysis Method for Your Next Application

Abstract This primer discusses three image-based methods that simplify the analysis of phase composition, porosity, and particle distribution, thus providing additional insight into the microstructure of materials.

Investigation of through thickness microstructure and mechanical properties in friction stir welded 7N01 aluminum alloy plate

An on-going problem in friction stir welded (FSW) joints used in the high-speed train sector is that the microstructure and mechanical properties can significantly vary in thick sections. Because inhomogeneous properties can reduce weld efficiency and degrade service performance, it is of some interest to understand how inhomogeneous properties can develop in FSW welds made from precipitation hardening alloys such as 7N01. In the current study, butt welds were made using 12 mm thick plates and then sectioned perpendicular to the weld line. Five 2.2 mm thick slices were cut from a section and used to measure tensile properties access the weld thickness. The microstructure was characterized using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) to measure variation in grain size and second phase particle distributions over the weld zone. Results showed that, with the exception of the top slice, yield strength (σy) and ultimate tensile strength (σUTS) obtained from the slices were fairly consistent and comparable to values from the full weld. Elongation (δ) was maximum at mid-thickness decreased significantly towards the crown. Although significantly reduced elongation was found at the top of the weld, and likely limits overall weldment ductility, elongation of the full FSW weld was improved over that of the base metal and can be attributed to enhanced post-necking straining. The finest grains and second phase particles were observed at mid-thickness. In comparison, the coarsest grains were observed at the top of the nugget. This microstructural variation can be understood by considering the temperature and strain field gradients that are generated in the plasticized zone. It is expected that the findings will help to promote a better understanding of post-weld microstructure development and mechanical properties of thick plates.

Effects of initial microstructure on the earring of aluminium alloys cartridge case

Defects obtained during impact extrusion of EN AW-5754 aluminium alloy during cartridge case production were investigated. In cartridge cases produced from the one metallurgical heat pronounced tendency to earing after impact extrusion observed/appeared. On the other hand the earing in cartridge cases from the other heat was not observed. Presence of earing is due to local difference in materials flow during extrusion. This behaviour is atriduted to dfference in second phase particle distribution in used preforms (slugs).

Pressure and particle property impacts on radiation in oxy-coal combustion

A numerical study evaluating the significance of scattering phase function, particle size, particle distribution and pressure in an oxy-coal combustor was conducted. Particle absorption and scattering coefficients were calculated from particle properties and Mie theory. Mie theory was also used to identify appropriate scattering phase functions as a function of particle size. A strongly forward scattering function represented by a Henyey-Greenstein function was found to match scattering behavior for particle diameters greater than approximately 10 μm. A comparison of highly forward scattering based on two mono-sized particle distributions (15 µm and 119 µm) and a polydisperse size distribution (27.9 µm SMD) showed small particles produced peak incident wall heat fluxes 30–40% greater than large particles due to the increased number density with the smaller particles. The polydisperse distribution produced flux profiles similar but slightly higher than the 15 µm mono-sized particles. Although strongly forward scattering was found to best represent particle scattering for this system, data did suggest that phase function/scattering coefficient influence becomes more important with increasingly small particle size. Two particle distribution profiles (narrow and wide) were used to represent different coal flame profiles. A wide particle distribution across the combustor diameter produced higher incident wall heat fluxes than a narrow distribution limited to the center region of the combustor. Increased particle size decreased the effect of distribution. Incident wall heat flux was found to increase with increasing combustor pressure up to approximately 5 atm and 10 atm, respectively, for wide and narrow particle distributions. This was primarily due to increased particle absorption and scattering coefficients. Additional pressure increases beyond this up to 20 atm had minimal impact on wall fluxes due to saturated values of the particle absorption coefficient.

A Novel Framework for Integration of Random-Walk Particle-Tracking Simulation in Subsurface Multi-phase Flow Modeling

Coarse-scale models are generally preferred in the numerical simulation of multi-phase flow due to computational constraints. However, capturing the effects of fine-scale heterogeneity on flow and isolating the impacts of numerical (artificial) dispersion, which increases with scale, are not trivial. In this paper, a particle-tracking method is devised and integrated in a scale-up workflow to estimate the conditional probability distributions of multi-phase flow functions, which can be considered as inputs in coarse-scale simulations with existing commercial packages. First, a novel particle-tracking method is developed to solve the saturation transport equation. The transport calculation is coupled with a velocity update, following the implicit pressure, explicit saturation framework, to solve the governing equations of two-phase immiscible flow. Each phase particle is advanced in a deterministic convection step according to the phase velocity, as well as in a stochastic dispersion step based on the random Brownian motion. A kernel-based formulation is proposed for computation of fluid saturation in accordance with the phase particle distribution. A novel aspect is that this method employs the kernel approach to construct saturation from phase particle distribution, which is an important improvement to the conventional box method that necessitates a large number of particles per grid cell for consistent saturation interpolation. The model is validated against various analytical solutions. Finally, the validated model is integrated in a statistical scale-up procedure to calibrate effective, or “pseudo,” multi-phase flow functions (e.g., relative permeability functions). The proposed scale-up framework does not impose any length scale requirement regarding the distribution of sub-grid heterogeneities.

Recrystallization and thermal shock fatigue resistance of nanoscale ZrC dispersion strengthened W alloys as plasma-facing components in fusion devices

Recrystallization and thermal shock fatigue resistance behavior of nanoscale ZrC dispersion strengthened bulk tungsten alloys (W-0.5 wt% ZrC, WZrC) as potential candidates for plasma-facing components were investigated. By employing heat treatments with isochronal experiments, the evolution of the tungsten grain size/orientation, second phase particle distribution, thermal conductivity and mechanical properties were systematically studied. The effects of edge-localized mode like transient heat events on the as-rolled and recrystallized WZrC were investigated carefully. Pulses from an electron beam with durations of 1 ms were used to simulate the transient heat loading in fusion devices. The cracking thresholds, cracking mechanisms and recrystallization under repetitive (100 shots) transient heat loads were investigated. Results indicate that the cracking threshold of all the WZrC samples is 220–330 MW/m2 (corresponding to a heat load parameter F = 7.0–10.4 MJ/m2s1/2) at room temperature and the heat bombardment induced recrystallization occurs at a heat parameter of 10.4 MJ/m2s1/2.

The effect of Germanium addition on mechanical properties& microstructure of Cu-Al-Ni shape memory alloy

This paper aims to study the effect of Ge addition in different percentages (0.3%wt,1%wt, 3%wt) on the micro structure and mechanical properties of Cu-14wt%Al-4.5wt%Ni shape memory alloy which prepared by casting method in vacuum induction furnace. Many tests and inspections such as optical and SEM examinations, DSC Measurement,XRD inspection, compression and Vickers hardness tests were investigated. The results show that there is an increase in the transformation temperatures, shape memory limits and decrease in hardness and increase in Young Modulus Also it was found that the increase of Ge content to 3%wt Ge gave better properties due to the formation of martensitic phase and Ge particles distribution in martensite matrix of SMA.

Effect of Micro-Voids on Crack Initiation and Propagation in Bending Deformation of Al-Mg-Si Alloy Sheet

The crack initiation and propagation during bending have been considered to be affected by second phase particles, micro-voids and shear-bands. However, the effects of the second phase particles and the micro-voids on the crack initiation and propagation during bending have not been fully investigation. In this study, the effect of the second phase particle distribution on the formation of micro-voids, and the effect of the micro-voids on the crack initiation and propagation during bending were investigated using the largest synchrotron radiation facility “SPring-8” and FE-SEM/EBSD. With the bending ratio increasing, the micro-voids increased around the coarse particles near the outer surface. In particular, coarse micro-voids were formed around coarse particles with a high aspect ratio on the shear-bands. At a large cracked part, coarse micro-void was observed at the outmost layer section as a crack initiation site, and coarse micro-voids and asheared fracture surface were observed at the crack propagation site. At the small cracked part with no propagation, cube orientation grains were located under the small crack. It was considered that these cube orientation grains inhibited the formation of shear-bands, therefore, propagation of the cracks did not occur at the small cracked area.

LBE–DEM simulation of inter-phase heat transfer in gas–solid cross jets

Lattice-Boltzmann equation (LBE)–Discrete element method (DEM) coupled simulation of a two-dimensional gas–solid cross jet is performed, focusing on the gas-particle two-way coupling effect on heat transfer characteristics. The Reynolds number is 1000, and particle Stokes numbers are 10, 25, and 50 under the same number flow rate of particles. The gas phase temperature field and particle distribution as well as the inter-phase heat transfer characteristics are studied and analyzed. The dominating effects, i.e. the mean temperature difference and mean heat transfer coefficient between the gas–solid phases, for the pre- and post- collision stages of the cross jets are illustrated respectively. The change of dominating roles is related to the dynamical response characteristics of particles.