Microstructure Properties Research Articles

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Diamond/Ni-based wear-resistant coatings were fabricated on 45 steel using induction cladding, followed by laser remelting of the gradient coatings. The microstructure, phase composition, hardness, and friction properties of the coatings were examined. Results revealed that the surfaces of the composite and gradient coatings primarily consisted of a hard γ-Ni matrix and phases such as diamond, Cr7C3, and Cr23C6. High-temperature diffusion results in a strong metallurgical bond between the coating and the substrate. The gradient coating design significantly reduce the physical property mismatch between the 45 steel substrate and the composite coating. While laser remelting increased chromium aggregation and achieved a more uniform distribution of Fe, Ni, and Si. XRD analysis indicated that the Ni2Si diffraction peaks disappeared. Concurrently, the surface roughness and wear loss of the coating decreased, while the microhardness of the surface layer increased to 1030.74 HV, enhancing surface wear and corrosion resistance performance.

Effect of Gd content on microstructure and mechanical properties of Mg-xGd-Zr alloys via semicontinuous casting

Mg-Gd based alloys are an important class of high-performance Mg alloys. In this study, three Mg-Gd alloys with different gadolinium (Gd) contents: Mg-9.54Gd-0.40Zr (wt.%, G10 K), Mg-15.11Gd-0.35Zr (wt.%, G15 K) and Mg-19.67Gd-0.33Zr (wt.%, G20 K) were prepared by semicontinuous casting and subsequent solution and aging heat treatments. The role of Gd content on microstructures and mechanical properties of the Mg-Gd-Zr alloy is studied. All three as-cast alloys exhibit eutectic phases of Mg5Gd, with the amount increasing as the Gd content rises. Mg5Gd disappears after the solution heat treatment (the G10 K alloy solution-treated at 480 °C for 4 h, the G15 K alloy at 500 °C for 12 h and the G20 K alloy at 520 °C for 24 h, respectively). Aging heat treatment at 200 °C for 64 h after solution introduces numerous prismatic β′ precipitates, with a significant increase in their area number density corresponding to increased Gd content. Additionally, the morphology of the β′ precipitates exhibits distinct variations: the G10 K alloy is characterized by an enhanced aspect ratio. Consequently, the peak-aged G10 K alloy demonstrates superior strength-ductility synergy, with a yield strength (YS) of 216 ± 1 MPa, an ultimate tensile strength (UTS) of 363 ± 1 MPa, and an elongation (EL) of 8.7 ± 0.6 %. This study suggests that plasticity diminishes and precipitation strengthening is limited when the gadolinium content exceeds 15 wt.%.

Influence of B4C incorporation on microstructure and mechanical properties of reactively spark plasma sintered (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2-SiC based ceramics

Influence of B4C incorporation on microstructure and mechanical properties of reactively spark plasma sintered (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2-SiC based ceramics

Microstructure and characteristics of Zn and Mg-doped LiNbO3 materials for electrochromic devices

In this investigation, polycrystalline targets of lithium niobate (LN), zinc-doped lithium niobate (Zn:LN), and magnesium-doped lithium niobate (Mg:LN) were synthesized utilizing the Hot Isostatic Pressing (HIP) and Cold Isostatic Pressing (CIP) sintering technique. Subsequently, amorphous thin films of LN, Zn:LN, and Mg:LN and electrochromic devices were fabricated via radio frequency (RF) magnetron sputtering. Comprehensive characterization of the microstructure and optoelectronic properties of the targets, films and devices was conducted employing scanning electron microscopy, X-ray diffraction, spectrophotometry, atomic force microscopy, and an electrochemical workstation. Studies have shown that doping with zinc and magnesium enhances the sintering quality of ceramics, reducing lithium vacancies in polycrystalline lithium niobate ceramics. Zinc doping increases the resistance of lithium niobate, whereas magnesium doping introduces a secondary phase that decreases the resistance. The resistances of LN, Zn:LN, and Mg:LN polycrystalline ceramics are 8.35 GΩ, 9.80 GΩ, and 7.61 GΩ, respectively. The doping process refines the growth of the target and film particles, enhancing the microstructural quality. Notably, the ionic conductivity of the Mg:LN film escalates to 1.7 × 10−5 S/cm. Using doped lithium niobate thin films as electrolytes, the electrochromic devices showed a 38 % increase in coloration efficiency and a 46 % improvement in bleaching efficiency, significantly enhancing device performance.

Enhanced vacuum brazing joining between Ti–48Al–2Cr–2Nb/Ti–22Al–25Nb intermetallic alloys by Zr-free Ti-based filler

This study investigates the microstructure and tensile properties of vacuum-brazed joints of Ti–48Al–2Cr–2Nb (Ti4822) and Ti–22Al–25Nb (Ti2AlNb) intermetallic alloys using Ti-based filler metals, with and without the addition of Zr element. Detailed microstructural characterization of the brazed joints was conducted using Electron Backscatter Diffraction and Transmission Electron Microscopy, identifying various phases and their distributions. The tensile properties were tested at room temperature and at 650 °C, revealing the influence of Zr on the mechanical performance of the joints. The results demonstrated that the microstructure of joints brazed with Zr-containing filler metals exhibited a layered structure with brittle Zr-enriched intermetallic compounds, limiting their mechanical properties. Conversely, Zr-free filler metals yielded more homogeneous and ductile microstructures, significantly improving tensile strength and elongation. The Zr-free joints obtained after holding at 980 °C for 60 min exhibits the highest tensile strength, reaching 368.23 MPa at room-temperature and 293.46 MPa at 650 °C, respectively. These findings provide valuable insights for optimizing brazing processes and filler metal compositions to enhance the performance of TiAl-based intermetallic alloy joints.

S1aUnnotched fatigue behavior of the lased powder bed fused and hot isostatic pressed Inconel 718 at 600 °C

The microstructure and mechanical properties of hot isostatically pressed (HIP) Inconel 718 additively manufactured using the laser beam powder bed fusion (LPBF) process were investigated at 600 °C, with emphasis on the high cycle fatigue behavior evaluated using the rotating bend fatigue tests, and elucidation of the role of γ” precipitate size on the fatigue resistance. Experimental results show that the unnotched fatigue strength (σf) of the peak aged alloy improves only by 7% after HIP, as compared to that of the non-HIP peak aged alloy, despite a significant improvement in the ductility due to HIP. Over-aging the HIP alloy, however, led to a further enhancement (by ∼14%) in σf. Fractographic analyses suggest that the fatigue crack initiation occurs from the intrusions and extrusions on the fracture surface of both versions of the aged alloy. Microstructural investigations reveal the presence of persistent slip bands (PSBs) with different morphologies in peak- and over-aged microstructures. A change in the deformation mechanism due to the size of precipitates was identified to be the reason for the formation of nano-grains (through dynamic recrystallization) within the PSBs of the alloy with a coarse γ” microstructure. In several {110} grains, ∼5 μm thick nanocrystalline grain zones formed on the specimen surface; they completely suppressed the formation of PSBs and enhanced the fatigue resistance of the HIP LPBF IN718 alloy in the over-aged condition.

Preparation and characterization of dressing-type emulsions formulated with hydrocolloids from the mango (Mangifera indica) peel

Mango is a popular tropical fruit known worldwide and mango peel is a waste product worthy of valorization. This study explores the stabilizing effect of hydrocolloids extracted from mango peel in dressing-type emulsions (DE). Emulsions stabilized with different ratios of mango (Mangifera indica) peel-derived hydrocolloids (PE) and guar gum (1% wt. total concentration) were prepared and characterized: DE1 (0.25/075), DE2 (0.5/0.5), DE3 (0.75/0.25) and DE4 (1/0). Particle size distribution, ζ-potential, proximal composition, color, microstructure, and rheological properties were evaluated. All the samples showed similar proximal compositions. However, PE/guar gum ratio influences color parameters. For the microstructural analysis, Sauter's mean droplet size ranged from 6.41 to 11.11 µm. The ζ- potential values ranged from -18.03±0.21 to -16.97 mV. Emulsions exhibited shear thinning responses that can be well described by the Williamson model, and gel-like viscoelastic character with G’ higher than G”. The activation energy values (Eα) deduced from the application of an Arrhenius model to the viscous flow behaviour of the emulsions ranged from 108.46 to 143.44 Kj/mol. From the microstructural analysis and the rheological characterization, it can be inferred that PE favors the flocculation of the emulsion droplet in high concentrations. Overall, this research contributes to the sustainable exploitation of a mango waste material, such as the peel, in food emulsions.

Influence of different rolling passes and deformation amounts on the microstructure evolution and strengthening mechanism of Cu-Ni-Si alloy

Under the condition of controlling the total rolling deformation to 80.0%, the effects of multi-pass rolling, the ratio of deformation between the first and second stages in two-stage rolling, and aging parameters on the microstructural evolution and property enhancement of Cu-Ni-Si alloy were investigated. The results showed that the second-stage rolling promotes the formation of high-density dislocations, significantly enhancing dislocation strengthening. Simultaneously, the high-density dislocations facilitate the precipitation of the second phase during aging, and concurrently improving the strength and electrical conductivity of the alloy. In the two-stage rolling and aging process, a ratio of first-stage to second-stage rolling deformation less than 1 yields superior comprehensive properties. Specifically, when the first-stage rolling deformation is 35.0% and the second-stage deformation is 68.8%, the alloy achieves an optimal electrical conductivity of 49.53% IACS, hardness of 272.9 HV0.1, tensile strength of 773.0 MPa, and yield strength of 723.3 MPa. This is because a rolling ratio less than 1 results in higher dislocation density; the δ-Ni2Si precipitates have a coherent relationship with the Cu matrix, the interparticle spacing of precipitates is smaller. The average grain size is refined from 1.29 μm to 1.08 μm, significantly enhancing grain boundary strengthening. Dislocation strengthening and second-phase strengthening are the primary strengthening mechanisms of the alloy, and the calculated alloy strength agrees well with the experimental values, with errors less than 3.4%. Additionally, the Avrami equation in phase transformation kinetics was utilized to study the variation law of the volume fraction of the δ-Ni2Si phase with aging time.

Microstructure and mechanical properties of MoNbVTa0.5Alx refractory high entropy alloys

The specific strength of refractory high entropy alloys (RHEAs) is usually impaired due to the high density of constituent elements. In order to develop a low-density RHEA, the microstructure and mechanical property of MoNbVTa0.5-based RHEAs with various Al additions have been investigated in this study. All samples exhibited a monolithic BCC solid solution structure. The addition of Al resulted in improved yield strength but a degraded plasticity at ambient temperature. In contrast, the yield strength consistently decreased with increasing Al content at elevated temperatures, and the softening occurred at ~1000 °C. MoNbVTa0.5Al0.3 exhibited high specific strengths of 119.2 MPa cm3/g, 108.6 MPa cm3/g and 97.3 MPa cm3/g at 600 °C, 800 °C, and 1000 °C, respectively.

Diffusion bonding of TA2 titanium and 20# steel with vanadium/chromium bimetal interlayers: Microstructure, unexpected carbides, and mechanical properties

V and Cr bimetals are utilized as interlayers in the vacuum diffusion bonding of TA2 Ti and 20# steel to prevent the formation of Ti–Fe intermetallic compounds and improve the interface compatibility. The microstructure and mechanical properties of the diffusion-bonded joints are investigated using optical microscopy, scanning electron microscopy combined with energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, nanoindentation, and tensile testing. The results indicate that the V/Cr bimetallic interlayer effectively inhibits the formation of Ti–Fe intermetallic compounds, with solid solutions without these compounds present at the Ti/V and steel/Cr interfaces. However, a 1–3-μm-thick continuous, hard, brittle vanadium carbide layer with hardness and elastic modulus value of 6.66 GPa and 201.55 GPa is unexpectedly discovered at the interface between V and Cr. The fracture morphology analysis reveals that the continuous carbide layer at the V/Cr interface is the primary cause of joint failure. The tensile strength of the joint remains relatively stable with an increase in the bonding temperature, whereas the elongation gradually decreases. A maximum tensile strength of 252 MPa is achieved with an elongation of 4.3%.

The effect of cold plasma pretreatment on drying efficiency of beetroot by intermittent microwave-hot air (IMHA) hybrid dryer method: Assessing drying kinetic, physical properties, and microstructure of the product

This study examined the effects of cold plasma (CP) pretreatment with durations of 1, 3, and 5 minutes on drying kinetics, microstructure, and physical properties, including shrinkage, rehydration ratio (RR), and bulk density of beetroot dried samples using intermittent microwave-hot air (IMHA) drying at 40 °C and pulse ratios (PR) of 1 and 2. While increasing PR decreased drying rate (DR) and effective moisture diffusivity (Deff), increasing microwave power from 180 to 600 W increased both, reducing drying time and specific energy consumption (SEC). Extended CP-pretreatment doubled DR, 66% increased Deff, and 24% reduced SEC. Both increasing CP-pretreatment time and microwave power had similar effects on shrinkage, RR, and bulk density, but CP-pretreatment was more prominent; reducing shrinkage by 18%, bulk density by 23%, and increasing RR by approximately 36% in 5-minutes. X-ray imaging showed that 600 W of microwave power increased porosity by 87%, while 5-minute CP-pretreatment increased it by 27%. As the optimum condition, CP-pretreatment for 5 minutes, continuous microwave application, and 600 W of MW power produced the best kinetics and physical properties. Overall, the results demonstrated that the appropriate CP-pretreatment duration could produce high-quality dried samples.

Microstructure and mechanical properties of aluminum alloy laser welded joint assisted by alternating magnetic field

Magnetic field-assisted laser welding is an effective method to improve the quality of laser-welded joints. In this study, laser welding was conducted on a 2 mm thick sheet of 6061-T6 aluminum alloy, with the assistance of an alternating magnetic field oriented perpendicular to the surface of the sheet. The effects of the alternating magnetic field on the macrostructure, molten pool flow, porosity, grain morphology, and microhardness of the weld seam were analyzed. The results indicate that applying the alternating magnetic field results in more uniform and finer fish scale patterns on the upper surface of the weld. The porosity of the weld is significantly reduced. The Lorentz force generated by the alternating magnetic field suppresses liquid metal flow from the center to the edges of the molten pool, thereby hindering the heat flow and transfer within the pool. This concentration of heat in the lower part of the molten pool increases the size of equiaxed grains at the weld center and promotes the formation of more branches in the columnar grains near the fusion line. Some columnar grains in the columnar grain zone transform into equiaxed grains. Moreover, the microhardness distribution of the weld becomes more uniform, and the hardness in the heat-affected zone increases. Tensile tests revealed that all samples fractured within the weld seam, with the tensile strength of the welded joints increasing by 12.7%. The fracture mode transitions from a mixed ductile-brittle fracture to a purely ductile fracture.

Microstructure and mechanical properties of Co-free AlCrFeNiTi0.2 eutectic high-entropy alloy

Microstructure and mechanical properties of Co-free AlCrFeNiTi0.2 eutectic high-entropy alloy

Microstructural, magnetic, and optical properties of nickel-doped spinel zinc ferrite nanoparticles

This study focuses on the synthesis of nickel-substituted zinc ferrite nanoparticles, , via the sol-gel method and examines how nickel substitution influences their structural, magnetic, and optical properties. The lattice constant of the nanoparticles, which varied from 8.4296 Å to 8.4212 Å, decreased as the nickel concentration increased. Scanning electron microscopy (SEM) was employed to examine the morphology, revealing grain sizes between 46 and 53 nm, while energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing nearly spherical nanoparticles containing all the constituent elements. The magnetic properties were analyzed using a vibrating sample magnetometer (VSM), which highlighted significant differences between the theoretical and experimental magnetic moments, indicating the presence of Yafet-Kittel magnetic ordering in the system. The saturation magnetization was enhanced by ions, reaching a maximum value of 23.864 emu/g. This enhancement makes the nickel-substituted zinc ferrite nanoparticles suitable for applications in data recording media and magnetic resonance imaging. Additionally, the values of the magnetic crystalline anisotropy constant, initial permeability, effective anisotropy constant, and anisotropic field of the synthesized samples were estimated.The optical properties of the synthesized samples were evaluated using UV-visible spectroscopy, and the band gap was determined through diffuse reflectance spectroscopy (DRS). The optical bandgap of pure zinc ferrite was measured to be 2.26 eV, and it decreased with increasing nickel concentration in the nanoparticles.

Effect of co-addition of Nb/Zr on the microstructure and soft magnetic properties of Fe77.5Si11.5B7NbxZr3-xCu1 nanocrystalline alloys

Effect of co-addition of Nb/Zr on the microstructure and soft magnetic properties of Fe77.5Si11.5B7NbxZr3-xCu1 nanocrystalline alloys

Microstructure, mechanical properties and deformation behavior of laser additively repaired 5083 and 6061 Al alloys utilizing AlMgScZr powders

Laser additive repair (LAR), as an efficient repair method, lacks specialized repair materials for Al alloys. In this work, the high-strength AlMgScZr powder was employed to address the scarcity of specialized materials and the issue of inadequate performance in LAR of 5083-H112/6061-T6 Al alloy. The microstructure, mechanical properties and deformation behavior of repaired specimens were studied. The repair zone (RZ) had high strength and high density, and the porosity was as low as 0.12 %. There was good compatibility between the repair material and the base metal (BM), and good metallurgical bonding was achieved at the fusion line. The microstructure and strengthening phase (T-phase) in the heat affected zone (HAZ) of the 5083 repaired parts exhibited negligible changes, there was no deterioration in mechanical properties. The yield strength was 162 MPa, tensile strength was 291 MPa, and elongation was 16.2 %, reaching 94 %, 104 %, and 70 % of the BM, respectively. The mechanical properties are superior in the current research on LAR of Al alloys. The LAR technique showcases its versatility in repairing aging non-strengthening Al alloys. The transition of β′′→β′ (or with B′/U1/U2)→β of the nano-reinforced phase resulted in deteriorative mechanical properties of HAZ in the 6061 repair part, consequently, the tensile strength of 6061 repair part was only 63.8 % of the strength of BM. After solution aging treatment, the β′′ phase in HAZ re-precipitated, effectively restoring the strength of 6061 repaired parts. The tensile strength of the repaired parts was increased to 95.2 % of the strength of BM. The present study elucidates the evolution of microstructure and mechanical properties during LAR process of Al alloys, offering valuable insights for future applications of this technology on Al alloys.

Achieving strength-ductility synergy of ODS-FeCrAl alloys via heterostructured strategy

Oxide dispersion strengthened (ODS)-FeCrAl alloys are candidate structural materials for advanced nuclear reactor applications, which have excellent strength and radiation tolerance but low ductility. In this study, a novel ODS-FeCrAl heterostructured composite, reinforced with FCC-structured ODS-CoCrFeNiMn high-entropy particles, was prepared by using mechanical alloying and spark plasma sintering to achieve the strength-ductility synergy. The effect of different reinforcement contents (0, 10, 15 and 20 wt.%, designated as RC-0, RC-10, RC-15, and RC-20, respectively) on the microstructure and mechanical properties of the composites was investigated. The results showed that the unreinforced reference alloy, RC-0, consists of BCC-structured ODS-FeCrAl matrix and high-density oxides. In the RC-10, RC-15, and RC-20 composites, in addition to the ODS-FeCrAl matrix and nanoscale oxides, FCC-structured ODS-CoCrFeNiMn high-entropy reinforcement with ultrafine grain size and FCC transition layer with gradient grain size are observed. As the reinforcement content increases, the thickness of transition region increases. The composites show an increase in ultimate compressive strength and compressive strain with increasing reinforcement content in the following order: 2951 MPa/33.6%, 3169 MPa/40.0%, 3290 MPa/43.2%, and 3489 MPa/48.8%. And the compressive yield strength exhibits an initial increase and subsequent decrease, i.e. 1523 MPa (RC-0), 1680 MPa (RC-10), 1635 MPa (RC-15), and 1355 MPa (RC-20), respectively. The increase in yield strength is mainly attributed to hetero-deformation induced (HDI) strengthening and reinforcement hardening. The improvement in ductility is mainly attributed to the HDI work hardening and the suppression of microcrack formation and propagation at prior powder boundaries.

Effect of trace Bi addition on the microstructure and mechanical properties of hypoeutectic Al-Mg-Si-Mn alloy

The effects of Bi on the eutectic structure and mechanical properties of AlMg5Si2Mn alloy were investigated. The results show that when trace Bi is added to the alloy, the eutectic Mg2Si phase in the alloy is successfully refined from long plate-like to fine fiber rod-like and coral-like structure. It is mainly attributed to the precipitation of Bi atomic clusters on the front of the solid-liquid interface and form a component supercooling, in which part of Bi atoms react with Mg atoms to form nanosized Mg3Bi2 particles, which effectively inhibits the rapid growth of eutectic Mg2Si and promotes the branching and refining of eutectic Mg2Si. The strength and ductility of AlMg5Si2Mn alloy containing Bi are significantly improved simultaneously. Compared to the unmodified alloy, the largest tensile strength, yield strength and elongation to failure of the 0.3wt % Bi-modified alloy are increased to 28.04%, 12.3% and 129.1%, respectively. The fracture mode of the alloy changes from brittle fracture to ductile fracture.

A Novel Preparation Approach of Aluminum-Based Functionally Graded Material: Auxiliary Wire Filling Gas Metal Arc Directed Energy Deposition

The 2319-1100 aluminum-based functionally graded material (FGM) with continuous gradient transition interface was fabricated by auxiliary wire filling gas metal arc directed energy deposition (AWF-GMA-DED) process via changing the feeding speed of the auxiliary wire ER1100. The droplet transfer behavior, deposition morphology, microstructure and mechanical property of the FGM wall were analyzed. Results indicate that with increasing feeding speed of ER1100, the droplet transfer mode of the auxiliary wire changes in the manner of large droplet transfer—bridge transfer—continuous transfer, while the droplet transfer of the main wire ER2319 is always stable. As the filling ratio of ER1100 increases, the area of interlayer equiaxed grain band and equiaxed grain size increases gradually, the continuity of eutectic structure at the grain boundary is weakened, and the eutectic structure is refined. When the ER1100 filling ratio increases from 10% to 35%, the microhardness decreases by 13.4%, the tensile strength 7.8%, whereas the elongation and corrosion resistance of the FGM part both improve.

Forming control and the relationship between microstructure and mechanical property in TIG-assisted friction stir welded joint of Ti-6Al-3Nb-2Zr-1Mo titanium alloy

In this paper, T-joints of Ti-6Al-3Nb-2Zr-1Mo titanium alloy were joined with friction stir welding, and microstructure evolution and forming mechanism were studied. The effect of using tungsten inert gas welding to heat additionally the FSW was investigated. Results show a strong effection microstructure of stir zone (SZ) due to the temperature gradient and fast cooling rate. The top and middle sections of SZ have a basketweave microstructure, while there is duplex microstructure at the bottom. When welding at 750 rpm-50 mm/min, the maximum tensile strength of the joint is similar to that of the base metal (BM). As the heat input increases, grain coarsening occurs, which reduces the joint tensile strength and the ability to plastically deform. The fracture mode changes from mixed fracture to ductile one. When TIG-assisted heat source is 20 mm in front of the tool and the power input is in 600 W, the temperature field produced is relatively uniform, which has a positive effect on the weld.