Al-4 Wt Research Articles

Low-temperature ignition and mechanism of μAl coated with bismuth citrate

Because of the existence of an oxide layer on the surface of micron aluminum (μAl) powder, it is difficult to ignite. In order to improve μAl ignition, Al particles were coated with bismuth citrate (Bi(cit)) by a solvent evaporation method. The morphology of Al-Bi(cit) was observed by scanning electron microscope (SEM) showed that Bi(cit) was evenly distributed on the surface of Al particles. The ignition temperature was reduced and ignition delay time at different temperatures of the Al-Bi(cit) were tested in a transparent tube furnace. With the increase of Bi(cit) content, the ignition temperature and ignition delay time shortened, and the combustion flame captured by the high-speed camera was more bright. The test results showed that Al-20 wt% Bi(cit) has a low ignition temperature of 479 °C, and the ignition delay time at 450 °C is only 7 s. The thermal behavior of Al-Bi(cit) was studied by thermogravimetric analysis (TG-DSC). Combined with the characterization results of the products at different heating temperatures, the combustion mechanism was proposed and proved.

Revealing nucleation kinetics of entrained eutectic Si droplets in high purity melt spun Al-5Si based alloys with additions of Ta, TiB2, Eu and P

High purity (HP) Al-5 wt% Si with additions of Ta, TiB2, Eu and P were produced by arc melting and melt-spinning. Nucleation kinetics of entrained eutectic Si droplets in HP melt spun Al-5Si based alloys was investigated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). No significant effect of Ta and/or TiB2 on nucleation kinetics and microstructure of entrained eutectic Si droplets was observed, although Al3Ta was observed at hyperperitectic concentrations. In contrast, a significant effect of Eu and/or P on nucleation kinetics and microstructure of entrained eutectic Si droplets was observed. Increasing P concentration increases the onset temperature and exhibits a lower undercooling required for the nucleation of entrained eutectic Si droplets. Large Al2Si2Eu phase was observed both within the Al matrix and along the boundaries of entrained eutectic Si droplets, while small Al2Si2Eu phase was also observed within entrained eutectic Si droplets. With increasing P, EBSD reveals the transition from fine randomly multiply-oriented fibrous eutectic Si to coarse single-oriented plate eutectic Si within the entrained eutectic Si droplets. With further increasing P, fewer coarse Si crystals were observed within the entrained eutectic Si droplets. EBSD indicates that the entrained eutectic Si droplet can be nucleated from AlP nucleation site.

Laser shock dynamic compaction of aluminum–copper (Al–Cu) composite metal powder

Laser impact dynamic compaction experiments and 2D multi-particle finite element method (MPFEM) simulations were carried out on aluminum–copper (Al–Cu) binary-based composite powders. Al–Cu compacts with densities of about 95% were successfully prepared at the maximum laser energy of 1.8 J. Research trends indicate that higher power lasers could nearly achieve the theoretical densities. Analysis of the influence laws of laser energy and copper powder mass fraction on the densities of Al–Cu compacts was carried out, and the effects of microstructure and microhardness of Al–Cu compacts on their mechanical properties were investigated, as well as the stresses and velocities in the dynamic compaction process of Al–Cu composite powders were analyzed. The results showed that the relative densities of composite powder compacts of Al-5 wt%Cu gradually exceeded those of Al-10 wt%Cu and Al-15 wt%Cu with the increase of laser energy. In laser impact dynamic compaction the mechanism of inter-particle joining was solid-state press-welding, and the increase in the hardness of the Al–Cu compacts could be attributed to the inherent hardness of the hard particles. The upper particles have a localized maximum velocity of more than 300 m/s, which met the explosion welding velocity, thus localized cold welding occurred and contributed to the inter-particle connection.

Investigation into microstructural and mechanical properties of Al–Sn alloy fabricated using accumulative roll bonding combined with heat treatment

Al–Sn-based alloy was produced using the accumulative roll bonding (ARB) process followed by heat treatment. The effect of ARB cycles and various heat treatment temperatures (300–600 °C) and times (15–60 min) was studied. Microstructural, structural, and mechanical properties of the samples were examined using scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS), hardness, tensile, and wear tests at room temperature. Microstructural observations featured aluminum grains with a grain-boundary distribution of the tin phase, confirming the successful production of Al–Sn alloy by using the ARB process followed by the heat treatment process. The ultimate tensile strength and hardness values of the produced alloys were 110 MPa and 45 HV, respectively, after 8th ARB cycles and heat treatment at 600 °C and holding for 30 min. Besides, the wear resistance of the prepared Al-12 wt% Sn alloy was increased when the ARB cycles increased from the first cycle to the 8th cycle. In conclusion, this study reflected that mechanical working (ARB process) combined with heat treatment is an appropriate route to achieve Al–Sn alloy with relatively suitable properties.

Magnetic monopole's role in hydrogen bubbles formation in rapidly solidified Al–Cu–Zn alloys

Hydrogen hydrides are formed when hydrogen is trapped in the aluminum solid solution of rapidly cooled Al–Cu–Zn alloys. The formation of these hydrides is of great interest because they have unique properties that make them useful in a variety of applications. One potential application is in the field of energy storage, where hydrogen hydrides could be used as a way to store hydrogen for use in fuel cells. Another potential application is in the field of catalysis, where these materials could be used to promote chemical reactions. Highlighting of magnetic monopoles in Al-30 wt%Cu-2wt.%Zn and stable skyrmions, at room temperature, in non-magnetic Al-50 wt%Cu-2wt.%Zn is also groundbreaking development in the field of materials science, as it suggests that there may be new ways to manipulate and control the properties of these materials. We observed a remarkable consequence of these phenomena: the transmutation of aluminum into silicon. This is a significant finding, as we believe we are the first to approach this process in this way. This could lead to breakthroughs in materials science and engineering, with potential applications in fields such as electronics, photonics, and nanotechnology.

Corrosion behavior and microstructure of Al–10Zn alloy with nano CuO addition

The present study explores the preparation of Al–10wt.%Zn alloy by the casting process. Nano CuO was prepared by the Co-precipitation method. The effect of adding nanostructure of (1wt.% CuO) to Al–10Zn alloy was studied the corrosion effects as-cast and with different aging temperatures (423, 443, and 463 K) for 2 h in 3.5% NaCl aqueous solution after homogenized for 2 h at 500 K at room temperature. Electrochemical measurements (OCP, Tafel, and EIS) were performed to determine the corrosion rate (C.R.) and corrosion current density (Icorr.) to find out corrosion behavior. In addition, microstructures of Al–10Zn and Al–10Zn–1CuO were observed using a scanning electron microscope, EDX mapping, and the optical microscope to investigate the effect of the nanoparticle’s addition before and after aging and the corrosion test. The average crystal size and the dislocation density were calculated from the XRD pattern. The results show that the appropriate addition of CuO nanoparticles can refine the Al–10Zn alloy and shift the Al–10Zn alloy to a more noble direction.

Tribological Characteristics of Spark Plasma Sintered Al-6 wt.%SiC Composite Explored by Gray-Fuzzy Optimization Approach

Tribological Characteristics of Spark Plasma Sintered Al-6 wt.%SiC Composite Explored by Gray-Fuzzy Optimization Approach

Effect of Mg on Al-Mg Alloy and Electroless Ni-P Codeposition of nano-Al2O3: Mechanical, Wear, and Corrosion Resistance Properties

The addition of magnesium to Aluminum alloys has become increasingly popular due to their lightweight, high strength, and corrosion resistance properties. Our research on high-content Mg doped 90, Al-10 wt% Mg alloy has shown that coating it with electroless Ni-P and codepositing nano-Al2O3 (0, 2.5, 5 and 7.5 wt%) can significantly improve its mechanical properties, resistance to wear & tear, and even corrosion resistance. The electroless Ni-P-5 wt% Al2O3 composite displayed a wear rate of 0.65×10−3 g/m at 12 N, a microhardness value of 598 HV, and remarkable thermal shock resistance. A strong and uniform bond was formed between the coating and substrate, and no delamination or cracking was observed. Polarisation curves in 3.5 wt% NaCl solution showed that the corrosion potential of the 90, Al-10 wt% Mg alloy was higher than that of Ni-P and Ni-P-nano Al2O3 composites, indicating that the incorporation of nano-Al2O3 into the Ni-P electroless bath provides superior corrosion protection. This cost-effective and simple approach makes the Ni-P-5 wt% Al2O3 nanocomposite coating an ideal choice for shielding Al-Mg alloys from corrosion. HIGHLIGHTS We examine the magnesium content in Al-Mg alloy Electroless Ni-P-5 wt% Al2O3 coating could improve the anti-corrosion properties of Al-Mg alloy The thermal shock test showed that the alloy had good thermal stability Microhardness and wear resistance increase with the addition of nano Al2O3 particles The electroless Ni-P-5 wt% Al2O3 composite shows a wear rate of 0.65×10−3 g/m at 12 N GRAPHICAL ABSTRACT

Effect of aging treatment on microstructure and mechanical properties of Al matrix composite reinforced by in-situ intragranular Al2O3

Age-hardening Al matrix composites (AMCs) exhibit great potential for developing advanced metal structural materials, while reinforcement configuration-dependent aging behaviors are still largely unclear. To gain an in-depth fundamental understanding of the effect of in-situ generated intragranular reinforcement on precipitation response, a systematical heat-treatment was applied for the in-situ generated Al2O3 reinforced AlCu composite prepared via powder metallurgical Al-5 wt% CuO (Al-5CuO) system. Results show that the nano-scale intragranular Al2O3 activates the dislocation-assisted bulk diffusion pattern to promote the precipitation response, thus effectively shortening the peak-aging time of the composite as compared to the referenced Al-4 wt% Cu alloy matrix (Al4Cu). The adequate precipitation within grains in the early-aging stage endows the peak-aged Al-5CuO composite with homogeneous size distribution of θ’ phase, contributing to the impressive mechanical properties. The mechanical analyses reveal that precipitation strengthening accounts for the prominent elevation of yield strength, while the enhanced ductility is achieved by decreasing the size and number density of precipitates segregated along reinforcement-matrix interface and grain boundary. This work yields new insights into intragranular reinforcement-driven precipitation response, which is crucial for designing age-hardening AMCs with high mechanical performance.

Effect of Multidirectional Forging and SIMA Process on Mechanical and Tribological Behavior of Hypereutectic Al-18 Wt.% Si Alloy

Effect of Multidirectional Forging and SIMA Process on Mechanical and Tribological Behavior of Hypereutectic Al-18 Wt.% Si Alloy

Anisotropic Tensile and Compressive Strengths of Al-4wt.%Cu Alloy Powder: Part 2—Effect of Dendritic Arm Spacings

This investigation focuses on the effects of the compaction directions (i.e., transversal and longitudinal) and microstructural arrays (inside the powder utilized to constitute the specimens) on the anisotropic strengths. The initial powders are obtained from the as-cast Al-4 wt.% Cu alloys solidified in two distinct cooling rates, i.e., ~0.5 and 2.5 °C/s. The powder particles are compacted by using 300, 400 and 600 MPa and sintered at 540 °C for 1 h. The compressive and tensile strengths are carried out and the anisotropic strengths are determined. It is found that transverse samples exhibit higher UCS (ultimate compressive strength) and UTS (ultimate tensile strength) than the longitudinal samples. It is also found that the powder compacted in the transversal direction and utilizing powder with finer dendritic arm spacing provides better UCS and UTS results. The novelty in the study concerns the fact that is evidenced in the role of the dendrite spacings concatenated with the compaction pressure and direction upon the mechanical behavior. It is concluded that depending on the compaction level intended or demanded mechanical behavior, the planning in the compaction direction is preprogrammed. Since recycled powder particles from conventional machining, drilling and turning can potentially be utilized to constitute parts and components, the environmentally friendly aspects are associated, and hazardous stages in a manufacturing process are substantially reduced or eliminated.

Influence of Heat Treatment on Microstructures and Shape Memory Effect of Cu-28Zn-2.5Al wt. % Produced by Gravity Casting

Cu-Zn-Al is one of the prospective shape memory alloys due to its promisingly good shape memory effect (SME), obtainable at a lower price through an easier fabrication process. Several hindrances that lower the SME of the Cu-Zn-Al can be improved by applying modified quenching methods and media. This study comprehensively studied the effects of quenching methods and media on Cu-28Zn- 2.5Al wt.% alloy. The alloy was fabricated by gravity casting and homogenized at 850 °C for 2 h. It was then betatized at 850 °C for 30 minutes and subsequently quenched using two different methods: direct quenching (DQ) and up quenching (UQ) with two different cooling media: water + dry ice (WD) and saltwater + dry ice (SD). Several characterizations to determine the material properties, such as morphology, structure, and hardness, were held, and additional semi-empirical bending tests were also conducted to determine the SME performance. The results showed that all quenched samples consisted of βʹ martensite [M18R] and retained α [A1] after quenching, regardless of the quenching method and cooling media. Upon analysis, the quenching with UQ method in SD media was found to be the most effective quenching process, as the method yields in an alloy with the highest SME performance. The pathway for achieving a high SME performance of Cu-Zn-Al alloy was thoroughly discussed in the article.

Iron aluminide FGM thin wall fabrication using CMT-based twin wire arc additive manufacturing process

An eleven-layered Iron aluminide functionally graded material wall structure was successfully fabricated using a cold metal transfer-based twin wire arc additive manufacturing (TWAAM) process. The microstructure was characterized by the non-epitaxial grain growth at the interface region between the first layer deposition and the substrate. Further, the microstructure morphology varied from large grains in the bottom layers to the columnar grains in the middle to the equiaxed grains in the top layers. The intermetallic phases confirm the Fe-rich Fe3Al in the bottom layers and FeAl in the top layers with increased Al wt.%. EDS elemental mapping confirms the Fe&Al distribution. The microhardness enhanced in the build direction of the FGM wall, which was in corroboration with the formed phases and the microstructure morphology.

Towards the work hardening and strain delocalization achieved via in-situ intragranular reinforcement in Al-CuO composite

Dense intragranular distribution of nanoscale reinforcements is highly desirable since it is effective in reconciling the strength-ductility trade-off in Al matrix composites (AMCs). Herein, we report a systematic investigation on the work hardening and strain delocalization in Al-5 wt.% CuO (Al-5CuO) composite with strength-ductility synergy contributed by in-situ dense intragranular nanoscale Al2O3. Results reveal that Al-5CuO exhibits prominent hetero-deformation induced (HDI) strengthening as indicated by its larger HDI stress than effective stress. We showcase that the notable pile-ups of geometrically necessary dislocations (GNDs) at intragranular Al2O3 result in the prevailing kinematic hardening. While the plastic relaxation dislocations (PRDs) around Al2O3 generated by the release of GND-induced internal stress produce isotropic hardening. Both contribute to the pronounced work hardening of Al-5CuO. Comprehensive characterizations suggest the GND distribution with marked intragranular feature in Al-5CuO during straining, which implies the effective provoking of grain interior rather than grain boundary (GB)/interfacial zone to take plastic strain. On basis of the well-described storage and annihilation of GNDs and PRDs at the intragranular Al2O3, the microstructure-based strain-hardening model enables an in-depth understanding of the kinematic and isotropic hardening contributions by Al2O3 in Al-5CuO. Systematic analysis further confirms the important roles of intragranular Al2O3 in improving the strain partitioning, strain/stress transfer and strength matching across different domains of Al-5CuO, which significantly contributes to strain delocalization and hence strength-ductility synergy. This work sheds important insights on the innovative design of strong and ductile AMCs with intragranular nanoscale reinforcements for structural applications.

A modified artificial neural network to predict the tribological properties of Al-SiC nanocomposites fabricated by accumulative roll bonding process

This work highlights the major influence of SiC concentration and plastic deformation on boosting wear rates of aluminum composites supplemented with SiC particles comprising varied volume fractions (0–4%). It also shows how a basic neural network model augmented with a particle swarm optimizer can forecast wear rates and coefficients of friction for complicated composites. According to the experimental findings, increasing the quantity of accumulative roll bonding (ARB) enhances SiC particle dispersion homogeneity. Increasing the number of cycles and introducing additional SiC particles helped to reduce the wear rate and increase the friction coefficient. After nine ARB cycles, the Al-4 wt.% SiC nanocomposite had the best improvement in both wear rate and friction coefficient. The same sample was also used in efforts to enhance the characteristics of hardness, and it was selected as having the highest level of hardness, which has grown by 139%. All of the generated composites evaluated at four different wear loads were able to be predicted by the proposed model with great accuracy, with determination coefficient R2 values of 0.9768 and 0.9869 for the frictional coefficient and wear rates, respectively.

Role of In Situ Formed (Al3Zr + Al3Ti) Particles on Nucleation of Primary Phase in Al-5 wt.% Cu Alloy

Role of In Situ Formed (Al3Zr + Al3Ti) Particles on Nucleation of Primary Phase in Al-5 wt.% Cu Alloy

Effects of TiO2, CuO, and SiO2 nanoparticles addition on the microstructure and mechanical properties of Al-10 wt% Zn alloy

This paper presents the effects of adding TiO2, CuO, and SiO2 (1 wt%) nanoparticles on the microstructure and mechanical properties of Al-10 wt% Zn alloy. A set of composite alloys was produced by incorporating SiO2, CuO, and TiO2 nanoparticles to the Al-10 wt% Zn alloy. Optical microscope (OM), scanning electron microscope (SEM) fitted with an Energy Dispersive Spectroscope (EDS), and X-ray diffraction (XRD) were used to investigate the microstructure of these alloys. The mechanical properties of the composite solders were assessed using the Vickers hardness tests. After a solution heat treatment at 500 K for 2 h, samples were immediately aged at 373 to 473 K for 2 h, followed by water quenching at 300 K. The experimental data indicated that Al-10 wt% Zn-1wt% SiO2 samples had the highest hardness values among all investigated composite alloys. The calculated porosity percentages of the composite alloys revealed that the Al-10 wt% Zn-1 wt% SiO2 samples had the lowest percentage. This finding can be attributed to the fact that these samples demonstrated the highest hardness values. The hardness of all composite alloys decreased with increasing the aging temperature with anomalous behavior at 443 K, where they had abnormally high values. The observed differences in the mean crystallite size, lattice strain, and dislocation density of the composite alloys, calculated from XRD data with increasing aging temperature, are attributed to the precipitation in Al-Zn alloys. The calculated values of the stress exponent and activation energy of composite alloys may be associated with grain boundary diffusion (GBD) as the dominant operating mechanism.

The effect of Cu coated Al2O3 particle content and densification methods on the microstructure and mechanical properties of Al matrix composites

In the study, aluminum-based nanocomposites were reinforced with different concentrations of Al2O3 nanoparticles ranging from 0 to 15 wt. %. The Al2O3 nanoparticles were coated by nano Ag and nano Cu by the electroless chemical composition to improve the wettability between the matrix and the reinforcement phase. The influence of the suggested deformation technique and the concentrations of Al2O3 nanoparticles on the microstructure, density, and mechanical properties in terms of hardness and compressive strength of the hot extruded Al/Al2O3 nanocomposites was studied. Results revealed that, as the concentration of nano Al2O3 particles increases, the mechanical properties were improved. XRD, FE-SEM equipped with EDX, and elemental mapping indicates a near-uniform distribution of reinforcement nanoparticles in the matrix. The relative density of the formed nanocomposite recorded a slight decreases than the extruded pure Al. Owing to the presence of the Al2O3 nanoparticles, the Al-15 wt. % Al2O3 hot extruded composite achieves a hardness of 136 and 132 measured on the cross and longitudinal sections, respectively, illustrating an improvement of around 109% over the extruded pure Al. The hot extruded Al/Al2O3 nanocomposites with 5, 10, and 15 wt. % content revealed compressive strength of 564, 579, and 763 MPa, respectively, with an enhancement of 97, 102, and 166% over those of the extruded pure Al.

Microstructure and thermal-physical properties of hypereutectic Al-Ni alloys

The microstructure and thermal-physical properties of Al-xNi (x = 6–25 wt.%) alloys were investigated by experiments first. With the increase of Ni content, the volume fraction and size of the Al3Ni increase significantly, while the morphology has no change. The thermal expansion coefficient (CTE) and the thermal conductivity (TC) decrease at the same time. The CTE of Al-6 wt.%Ni alloy is 20.2 × 10−6/K at 100 °C, decreasing to 15.4 × 10−6/K for Al-25 wt.%Ni, which demonstrates favorable thermal expansion performance. The TC changes from 202.8 W/(m·K) to 103.9 W/(m·K). Besides, the structure and thermal properties of Al3Ni were studied by the first-principles calculation to provide relevant thermodynamic data. The expansion performance was analyzed at the same time, the linear CTE of Al3Ni is 13.82 × 10−6/K at 100 °C. Based on the experiments and first-principles calculations, the modified Turner and general Effective Medium Theory (GEMT) models were used to explain the relationships between microstructure and thermal expansion coefficient, thermal conductivity of Al-xNi alloys.

Mechanistic study of incipient corrosion for nuclear grade lean-Cr FeCrAl alloys in a simulated PWR environment

This study systematically investigated the incipient corrosion behavior of Fe-13Cr-4.5Al (wt%) and lean-Cr (7–10 wt%) with 5Al (wt%) FeCrAl alloy with a timescale of 4 months under simulated PWR conditions (18.6 MPa and 360 °C) in an autoclave system. The corrosion induced two types of structure of oxide scale. FeCrAl alloys corroded for 3 months exhibited a duplex structure containing outer oxide particles and an inner Cr-rich spinel. During the corrosion test lasting 3–4 months, a triplex structure containing outer oxide particles, an inner compact Cr-rich spinel layer, and a porous spinel layer was observed. Moreover, Cr enriched at the periphery of outer oxides, indicating the formation of FeCr2O4 spinel oxide.