Properties Of Ag Research Articles

Synthesis and study of the impact of calcination duration on the properties of Al4(ZnO)96 nanoparticles

Aluminium doped zinc oxide (Al4(ZnO)96) nanoparticles were synthesized using new sogel method at 40 °C, with zinc acetate dihydrate (Zn(CH3COO)2·2 H2O) and aluminium nitrate nonahydrate (Al(NO3)3·9 H2O) as precursors. The samples underwent analysis using various structural and optical techniques to investigate the effect of calcination duration on the properties. Prolonged calcination durations led to a significant reduction of oxygen at the grain boundaries, influencing particle size and crystallization. According to TEM-histogram analysis, the most probable size for 28.5 % of nanoparticles fell within the range of 15–20 nm, which aligns closely with the estimated particle size determined by XRD analysis. The material displayed a significant direct bandgap of approximately 3.283 eV, which increased with the duration of calcination. The band gap was affected by changes in phase, strain, and particle size, attributed to the presence of defect states and a substantial concentration of localized states. Additionally, the material exhibited excellent chemical stability and a significantly high binding energy. Moreover, the optical bandgap widened as the width of the Urbach tails in the localized states decreased with an increase in the duration of calcination.

Improve the microstructure and properties of Al0.5CoCrFeNi compositionally complex alloy fabricated by selective laser melting with electropulsing treatment

In order to improve the microstructure of the Al0.5CoCrFeNi compositionally complex alloy (CCA) prepared by selective laser melting (SLM), the electropulsing treatment (EPT) has been used as a post processing in this study. The strengthening and softening mechanism was analyzed by comparing the microstructure of SLM-Al0.5CoCrFeNi CCAs under different EPT parameters. At a 10 s power on time, the substructure size of CCA decreases continuously with increasing voltage. Under 90V/10s EPT, the yield strength increases from 658 ± 10 MPa in the printed state to 748 ± 17 MPa, and the microhardness increases from 265.1 ± 5.6 HV0.1 to 318.9 ± 5.0 HV0.1. At 90V/20s EPT, the cellular substructure disappears, and a large number of uniformly distribute BCC phases precipitates inside the FCC matrix. At 90V/30s EPT, recrystallization occurs and the BCC phase coarsen. Dislocation network is the main factor that affects the strength of SLM-CCA. EPT can change the dislocation network structure to enhance the strength of SLM-CCA. Simultaneously, the EPT effectively promotes the transition from FCC phase to BCC phase in a short time. Joule heat and electronic wind force are the main reasons for changing structure and properties of SLM-Al0.5CoCrFeNi CCA. This work provides a post-processing method named as EPT to effectively control the microstructure in additive manufacturing CCA products.

On two extensions of the annihilating-ideal graph of commutative rings

Abstract Let R be a commutative ring with A ⁢ ( R ) {A(R)} its set of annihilating-ideals. The extended annihilating-ideal graph of R, denoted by AG ¯ ⁢ ( R ) {\overline{\mathrm{AG}}(R)} , is an undirected graph with vertex set A ⁢ ( R ) * = A ⁢ ( R ) ∖ { 0 } {A(R)^{*}=A(R)\setminus\{0\}} and two vertices I 1 {I_{1}} and I 2 {I_{2}} are adjacent if and only if I 1 m ⁢ I 2 n = 0 {I_{1}^{m}I_{2}^{n}=0} with I 1 m ≠ 0 {I_{1}^{m}\neq 0} and I 2 n ≠ 0 {I_{2}^{n}\neq 0} , for some positive integers m and n. In this paper, we first study some basic properties of AG ¯ ⁢ ( R ) {\overline{\mathrm{AG}}(R)} and then we investigate the relationship between the extended annihilating-ideal graph AG ¯ ⁢ ( R ) {\overline{\mathrm{AG}}(R)} , the annihilator-ideal graph A I ⁢ ( R ) {A_{I}(R)} and the annihilating-ideal graph AG ⁢ ( R ) {\mathrm{AG}(R)} of a commutative ring R.

Tuning microstructure via cold deformation and annealing for superb mechanical properties in Al0.5CoFeCrNiSi0.25 dual-phase high-entropy alloys

In the field of metal materials, deformation and annealing play an irreplaceable role in improving the microstructure and optimizing the properties. In this study, we prepared Al0.5CoFeCrNiSi0.25 dual-phase high-entropy alloys (DHEAs) by vacuum arc melting and investigated their microstructure evolution and mechanical properties at different rolling and annealing temperatures. The results showed that the volume ratio of the FCC phase remained largely unchanged with increasing annealing temperature, with only small recovery for 10% reduction alloy. In contrast, the volume fraction and recrystallization ratio of the FCC phase in a 40% reduction alloy increased, and its recrystallization rate was higher than that of the BCC phase. Annealing the alloys at 900 °C formed the FCC, BCC, σ, L12, and B2 phases. As the annealing temperature increased to 1100 °C, the lamellar structure was changed, and the L12 and σ phases dissolved, leading to the gradual increase in the spacing size and volume fraction of the FCC phase. Increasing the annealing temperature reduced the yield strength but enhanced the ductility of DHEAs. Annealing for 1 h at 900 °C after 40% cold rolling enhanced their strength to 1360.61 MPa due to the high dislocation density and presence of σ phases but led to poor ductility. Annealing for 1 h at 1100 °C after 40% cold rolling produced a good combination of tensile strength (∼1267.8 MPa) and ductility (uniform elongation of ∼34.4%). Such remarkable strength and ductility may be attributed to the increased volume fraction of the FCC phase and the dual-phase heterogeneous deformation induction strain hardening effect.

The Effect of Quenching in Different Concentrations of Alumina Nano Fluids on Overall Properties of Al-6061

The Effect of Quenching in Different Concentrations of Alumina Nano Fluids on Overall Properties of Al-6061

Microstructural stability and properties of Al1.2CrCuFeNi2 dual-phase high entropy alloy

The microstructural stability and mechanical properties of novel Al1.2CrCuFeNi2 dual-phase high entropy alloy (HEA) were investigated. The as-cast alloy was composed of a uniform near-eutectic structure consisting of Ni-Al rich B2 matrix and Cr-Fe rich BCC spherical phases (mean grain size: ∼100 nm). Annealing at 1000 °C results in the precipitation of ultrafine particles and transformation from spherical phase to needle shaped structure. The as-cast HEA has an excellent combination of super yield strength (∼1326 MPa), fracture strength (∼1762 MPa) and plastic strain (∼24 %). After annealing, the compressive yield strength and fracture strength increase by ∼ 18 % and ∼ 13 %, respectively. This is mainly ascribed to the precipitation strengthening of ultrafine particles and the significant crystal lattice distortion strengthening in HEA. Besides, Vickers hardness increased from 548 HV to 612 HV implying that the Al1.2CrCuFeNi2 HEA projects excellent tempering softening resistant.

Effect of Y on Microstructure and Properties of Al0.8FeCrCoNiCu0.5 High Entropy Alloy Coating on 5083 Aluminum by Laser Cladding

To improve the surface properties of 5083 aluminum, Al0.8FeCrCoNiCu0.5Yx (x = 0, 0.05, 0.1, and 0.2) high-entropy alloy coatings were prepared by laser cladding. The phase structure and microstructure of the Al0.8FeCrCoNiCu0.5Yx coatings were characterized by XRD and SEM. The tribological properties of the coating were tested by a friction and wear tester. An electrochemical workstation tested the corrosion resistance of the coating. The results show that when Y content is less than 0.2, the Al0.8FeCrCoNiCu0.5Yx coating is in the FCC1, BCC1, and BCC2 phases. When Y is added to 0.2, the coating appears rich in the Y phase. With the increased Y content, the hardness of the coating can increase. The average hardness of Y0, Y0.05, Y0.1, and Y0.2 are 479HV0.2, 517HV0.2, 532HV0.2, and 544HV0.2, respectively. Microstructure evolution leads to an increase in the hardness of the coating. The effect of Y on the wear resistance of the Al0.8FeCrCoNiCu0.5Yx coatings is consistent with the hardness. Al0.8FeCrCoNiCu0.5Y0.2 coating has the lowest wear rate, at is 8.65 × 10−6 mm3/Nm. The corrosion current density of Al0.8FeCrCoNiCu0.5Y0.05 and Al0.8FeCrCoNiCu0.5Y0.1 coatings is in the order of 10−8, which is less than Al0.8FeCrCoNiCu0.5Y0.2 and Al0.8FeCrCoNiCu0.5. The performance of each component coating is superior to that of the substrate.

Corrosion and wear behaviors of brick powder reinforced aluminum composites manufactured by stir casting

Aluminum 6061 (Al6061) possesses good mechanical properties, strength, hardness, and corrosion resistance. However, the properties of Al6061 can be sufficiently raised by making composites. Metal matrix composites (MMCs) are well known for their high strength and corrosion resistance. However, these properties depend on the reinforcement materials added to the metal matrix. In the present work, Al6061-based MMCs have been manufactured by stir casting. In these MMCs, brick powders are used as reinforcement materials. Four MMCs have been developed by varying concentration and size of brick powders: MMC1, 2 h ball milled and 1% by weight; MMC2, 2 h ball milled and 7% by weight; MMC3, 4 h ball milled and 1% by weight; and MMC4, 4 h ball milled and 7% by weight. The successful formation of MMCs is examined by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. The corrosion and wear resistance of the manufactured MMCs have been investigated by electrochemical measurements and a pin-on disc tribometer. Based on the results of both tests, MMCs can be ranked as MMC4 > MMC3 > MMC2 > MMC1. The reason for improved behavior can be quoted as an enhancement in overall hardness and interaction of reinforced material with the matrix. To support this statement, the Vickers hardness of Al6061 and the developed composites have also been measured.

Effects of Fe on L12 phase precipitation and mechanical properties in Al0.3CrFeCoNi high-entropy alloy

The newly developed L12-strengthened high-entropy alloy shows great potential to possess superior combinations of physical and mechanical properties. It has been extensively studied how to control the L12 phase by adjusting L12-phase forming elements such as Al, Ti, Ta and Nb. However, the effect of transition-metal elements on L12 precipitation is still unclear. This work investigated the effect of Fe on the stability and distribution of the L12 phase by reducing the level of Fe in a well-studied high-entropy alloy Al0.3CrFeCoNi. A close examination of the precipitation behaviour in the Al0.3CrFeCoNi and Al0.3CrFe0.6CoNi1.4 alloys was conducted using transmission electron microscopes. When the aging temperature reaches 700 °C in the Al0.3CrFeCoNi alloy, nanosized L12 particles would transition to the B2 phase. By reducing the amount of Fe, the stability and density of the L12 phase were both enhanced. After 700 °C annealing, L12 nanoparticles are still stable in the Al0.3CrFe0.6CoNi1.4 alloy and there is no evidence of B2 phase precipitation. Less Fe can lower the concentration of Al in both the fcc and L12 phases during aging at a lower temperature of 620 °C when the L12 phase in both alloys is stable. A lower Fe concentration can also lead to more Cr and Fe atoms occupying Al sites in the L12 phase, which can result in the formation of more L12 particles. Since more L12 particles were precipitated when the amount of Fe was reduced, the Al0.3CrFe0.6CoNi1.4 alloy exhibits better strength and higher hardness than the Al0.3CrFeCoNi alloy. These findings give us insight into how transition metals affect the behaviour of L12 precipitation and suggest ways to develop and improve L12-strengthened HEAs.

Cooling-Rate Effect on Microstructure and Mechanical Properties of Al0.5CoCrFeNi High-Entropy Alloy

Al0.5CoCrFeNi high-entropy alloy (HEA) was prepared by spark plasma sintering (SPS) using Al0.5CoCrFeNi gas atomized powder and was treated with different cooling rates (furnace cooling, air cooling, water quenching). The phase composition, microstructure, tensile properties, Vickers hardness, compactness, and fracture morphology of the alloy were systematically studied. The results show that the cooling rate can change the phase composition and phase shape of Al0.5CoCrFeNi HEA from BCC + FCC phase to BCC + FCC + B2 phase, and the BCC phase coarsens. The ultimate tensile strength and yield strength of the heat-treated Al0.5CoCrFeNi HEA decreased with increasing cooling rate, but elongation and Vickers hardness increased with increasing cooling rate. The ultimate tensile strength and yield strength of the furnace cooling (FC) samples reached the maximum value of 985.2 MPa and 524.1 MPa, respectively. The elongation and hardness of the water quenching (WQ) samples reached a maximum value of 43.1% and 547.3 HV, respectively, and the compactness of the alloy is higher than 98.8%. Therefore, the properties of Al0.5CoCrFeNi HEAs can be greatly improved by treatment with different cooling rates.

Effects of Nb Additions on the Microstructure and Tribological Properties of Al0.25crfeni1.75 High-Entropy Alloy

Effects of Nb Additions on the Microstructure and Tribological Properties of Al0.25crfeni1.75 High-Entropy Alloy

Investigation on microstructures and properties of Al1.5CoCrFeMnNi high entropy alloy coating before and after ultrasonic impact treatment

To investigate the effect of plastic deformation with high strain rate on the microstructure and properties of Al1.5CoCrFeMnNi high entropy coating, ultrasonic impact treatment (UIT) was applied on the surfaces of the cladding coatings. According to the results, before and after UIT, the phase composition of Al1.5CoCrFeMnNi cladding coating did not change, remaining FCC and BCC dual-phase structure. Enormous dislocations were produced and accumulated introducing a cumulative strain by severe plastic deformation, forming a gradient structure. Moreover, the impacted layer with a low surface roughness exhibited the higher hardness, plastic deformation resistance and elastic modulus for the grain refinement and the preferred orientation on (1 1 1) crystal plane. But the surface toughness of the impacted specimen was decreased. There is an evident improvement of corrosion resistance for Al1.5CoCrFeMnNi cladding coating after UIT. The application of UIT on high entropy alloy provide a general and efficient method to strengthen the surface of block material.

Effect of boron on mechanical and anti-corrosion properties of Al0.3CoFeMnNi high-entropy alloys

A series of Al0.3CoFeMnNiB x high-entropy alloys (x = 0−0.5 in molar ratio) were prepared by vacuum arc melting method. The as-cast Al0.3CoFeMnNi alloy possesses face-centered cubic crystal structure. With boron addition, interdendritic borides are formed. The volume fraction and size of the borides increase with the enhancement of the boron content. The hardness dramatically rises from 4.04 GPa to 8.06 GPa with improving x from 0 to 0.5. The maximum yield strength and compressive strength were found to be 1050 and 1710 MPa, respectively, when x is 0.4. The compressive strain continuously decreases from 37.0% to 24.9% as x increasing from 0.2 to 0.5. The corrosion resistance gradually degrades with increasing the boron content.

The effect of nanometer phase SiC addition on the microstructure and mechanical properties of Al0.6CrFe2Ni2 high entropy alloys

ABSTRACT To improve the strength of single FCC phase Al0.6CrFe2Ni2 high entropy alloy without reducing the plasticity, nano-phase SiC was selected as reinforcement phase. Aseries of as-cast SiC/Al0.6CrFe2Ni2 high entropy alloys with different SiC content (0, 1.25, 2.5, 3.75, 5 vol%) were prepared by vacuum arc melting furnace. And the effect of SiC addition on the microstructures and mechanical properties of Al0.6CrFe2Ni2 high entropy alloy was analysed by microstructure observation, element distribution analysis, compression tests and hardness tests. The results show that the Cr7C3 particles were found in the grain boundaries due to the decomposition of SiC in high temperature, the size and quantity of Cr7C3 particles grow and spread throughout the alloy gradually with the further increase of SiC content. When the added SiC content is 2.5 vol%, the alloy has better comprehensive properties, the yield strength and hardness are 618.43 MPa and 250.78 HV, respectively.

Experimental investigation of mechanical and tribological properties of Al6061–ZrC–B4C hybrid composites

Aluminium metal matrix composites (ALMMCs) have been widely used because of their superior properties such as high strength to wear ratio, high wear resistance, and higher heat conduction rate. The addition of reinforcements in the form of discontinuous particles leads to an increase in the properties of metal matrix composites (MMCs). In the present study, ALMMCs were fabricated with the addition of discontinuous reinforcement particles of zirconium carbide (ZrC) and boron carbide (B4C). The mechanical properties such as tensile strength, hardness, and impact strength were tested as per ASTM standards. The tribological properties were tested using a pin-on-disc setup under different loading conditions (10, 20, 30, 40 N). Moreover, the morphological characterisation of the ALMMCs was carried out by scanning electron microscope (SEM) analysis. Furthermore, differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were performed to find the thermal stability of the ALMMCs. The findings show that variations of reinforcement of ZrC added gave improved properties such as hardness, tensile strength, impact strength, and wear resistance.

Microstructural Evolution of Al-Zn-Mg-Cu Alloys in Accordance with Homogenization Time.

The microstructural evolution of Al-Zn-Mg-Cu alloys has been investigated for the homogenization time effect on the texture, grain orientation and dislocation density. The Al-Zn-Mg-Cu alloys were casted and homogenized for 4, 8, 16 and 24 hours. Electron backscatter diffraction (EBSD) analysis was conducted to characterize the microstructural behavior. Micropillars were fabricated using focused ion beam (FIB) milling in grains of specific crystallographic orientations. Coarse precipitations in the grain boundaries are S (Al₂CuMg) and T (Al₂Mg₃Zn₃) phases verified by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) observation. With increasing homogenization time, equiaxed cell sizes increased. The volume fraction of S and T phases decreased with the diffusion of atomic elements into matrix. The Vickers hardness and tensile strength values decreased with homogenization temperature. The micropillar compression analysis was compared to macro tensile test results to understand the size effect and strain burst phenomenon on the mechanical properties of Al-Zn-Mg-Cu alloys.

Effect of vanadium addition on microstructure and properties of Al0.5Cr0.9FeNi2.5 multi-principal alloys

Al0.5Cr0.9FeNi2.5Vx (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) multi-principal alloys were prepared by vacuum arc melting. The effect of vanadium addition on its microstructure and properties was investigated. The results show that the alloys of all components exhibited an FCC single-phase structure. With the addition of vanadium, the microstructure of the alloy changed from dendrites to equiaxed crystals, the grains were remarkably refined, and the layered CrV phase was exhibited, which improved the properties of the alloy. The yield strength of the alloy was slightly improved, and the alloys with various components presented good plasticity. When V content reached 0.8, the yield strength was 600 MPa, and no fracture occurred. Friction–wear testing showed that the wear debris was reduced with the addition of V element. The sample with V element content of 0.4 had the best friction and wear performance. The surface grooves became shallow, the worn debris was less, and the wear mechanism was mainly abrasive wear. The polarisation curve showed that the alloy with V element content of 0.2 has the best corrosion resistance. The passivation interval reached 900 mV. The corrosion potential and the corrosion current density were − 496.299 mV and 2.759 μA/cm2, respectively.

Dynamic recrystallization-induced temperature insensitivity of yield stress in single-crystal Al1.2CrFeCoNi micropillars

High-entropy alloys, a new class of metallic materials, exhibit excellent mechanical properties at high temperatures. In spite of the worldwide interest, the underlying mechanisms for temperature dependence of mechanical properties of these alloys remain poorly understood. Here, we systemically investigate the mechanical behaviors and properties of Al1.2CrFeCoNi (comprising a body-centered cubic phase) and Al0.3CrFeCoNi (comprising a face-centered cubic phase) single-crystal micropillars with three orientations ([100], [110], and [111]) at temperatures varying from 300 to 675 K by using in situ compression of micropillars inside a scanning electron microscope. The results show that the yield stresses of Al1.2CrFeCoNi micropillars are insensitive to temperature changes, and their flow stresses and work hardening rates increase slightly with increasing temperature from 300 to 550 K, which differs from the typical temperature dependence of yield/flow stresses in metals and alloys. In contrast, Al0.3CrFeCoNi micropillars exhibit typical thermal softening. Furthermore, it is found that the Al1.2CrFeCoNi micropillars exhibit a transition from homogenous deformation to localized deformation at a critical temperature, while the Al0.3CrFeCoNi micropillars always maintain a well-distributed and fine slip deformation. Detailed transmission electron microscopy analyses reveal that dynamic recrystallization (involving dislocation tangles, and formation of dislocation cell structures and sub-grains) plays a key role in the observed temperature insensitivity of the yield stress and increasing flow stress (and work hardening rate) with increasing temperature in the Al1.2CrFeCoNi micropillars, and that thermally activated dislocation slip leads to thermal softening of the Al0.3CrFeCoNi micropillars. The differences in deformation modes and temperature dependence of the mechanical properties between Al1.2CrFeCoNi and Al0.3CrFeCoNi essentially originate from the differences in dislocation activities and slip systems since the two alloys adopt different phases. Our findings provide key insights in the temperature dependence of mechanical properties and deformation behaviors of high-entropy alloys with body-centered cubic and face-centered cubic phases.

Evolution of Microstructures and Compressive Properties in Al0.5CrFeNi2.1Mn0.8Tix High Entropy Alloys

The effects of Ti on the microstructures, macrohardness and compressive properties of the as-cast Al0.5CrFeNi2.1Mn0.8Tix HEAs were investigated. The results showed that the microstructures of as-cast Al0.5CrFeNi2.1Mn0.8Tix alloys was changed from FCC phase to a mixture of FCC and BCC phases, then to a mixture of BCC phase and Ti-containing intermetallic compound as the increasing of Ti content. Chrysanthemum-like eutectic microstructure was obtained in the Al0.5CrFeNi2.1Mn0.8Ti0.5 and Al0.5CrFeNi2.1Mn0.8Ti alloys. The area of flower core was composed of BCC2 phase, and eutectic microstructure was achieved in the petal area which contained BCC1 phase and BCC2 phase. Moreover, the macrohardness of the as-cast alloys increased with the increasing of Ti, and the Al0.5CrFeNi2.1Mn0.8Ti0.5 alloy showed excellent comprehensive compressive properties.

PHOTOBIOCONJUGATES OBTAINED BY SYNTHESIS NANOPARTICLES AG0 AND CDS IN PHYCOERITHRIN: PROPERTIES USEFUL FOR MEDICINE

New photosensitive bioconjugates of phycoerythrin (PE) with Ag0 and CdS nanoparticles have been obtained and characterized. Optical, photochemical and electrical properties of Ag0•PE and CdS•PE can be useful for their applications in multifunctional technologies, at creating intellect materials, potentiometric sensors controlled by light, etc.