Aluminum Bronze Research Articles

Effects of heat treatment on the microstructure and corrosion behavior of manganese aluminum bronzes

Abstract Due to a much lower nickel content, manganese aluminum bronzes (MAB) are a cost-effective alternative to nickel aluminum bronzes (NAB). When the material is processed, different microstructures are observable in the material which have an impact on the corrosion resistance of MAB alloys. MAB samples were annealed at 900 °C and quenched in water. After that, annealing treatments at 600, 500, 400 and 300 °C for up to 24 h were performed and the samples were again quenched in water. Metallographic sections were prepared from all samples and potentiostatic corrosion tests at different potentials were performed in synthetic seawater. It was found that the sample annealed at 900 °C and quenched in water as well as those samples which underwent a second annealing treatment at low temperatures for shorter times exhibited a greater corrosion tendency than those undergoing a second annealing treatment at higher temperatures. X-ray diffraction measurements revealed that phase transformations and changes in grain size occurred during the annealing treatments. The increase in corrosion resistance as a result of annealing at higher temperatures is probably due to the strong intergrowth of the phases that are formed.

Erosion-corrosion behavior of Ni-Al-Cu coating on nickel-aluminium bronze alloy in 3.5 wt% NaCl solution

A Ni-Al-Cu coating was prepared on NAB alloy through electroplating and heat treatment, and the erosion-corrosion behaviors were investigated. The results demonstrated that Ni-Al-Cu coating exhibited higher erosion resistance compared to NAB alloy, with an average reduction of 63 % in material removal rate (MRR). It was revealed that deformation and cracks were observed in NAB, with loss of hard κ and β phases alongside deformation of ductile α phase. Meanwhile, Ni-Al-Cu coating experienced fatigue delamination and grain disintegration due to alternating stress. Taguchi design method showed that increasing flow velocity and sand concentration could enhance the intensity of gravel impact, while changes in the erosion angle affected gravel impact modes and energy transfer, thereby impacting corrosion performance. Additionally, empirical equations for the material removal rate were derived through regression analysis, which became possible to predict the MRR under different influencing factors and assess the erosion-corrosion resistance of materials.

High temperature tribological properties of additively manufactured WC reinforced CuAl7–W composites

A wear-resistant composite material based on aluminum bronze with an addition of tungsten and tungsten carbide particles is developed using a combined wire- and powder-feed additive electron beam technology. The wear tests conducted under dry sliding conditions at room and elevated temperatures demonstrate a significant increase in wear resistance without any significant changes in the friction coefficient. Specifically, the composite with a particle content of 10 % exhibits an average wear rate 1.6 times lower compared to that of pure aluminum bronze, while the composite with a particle content of 20 % shows a 3.9-times wear rate reduction. The wear of the steel counterfaces during the composite sliding remains close to the values observed in a similar process for pure bronze.

Influence of powder heat treatment and particle size on the corrosion performance of cold-sprayed nickel-aluminum bronze (NAB) for repair applications

Nickel-Aluminum-Bronze powder was heat-treated to reduce martensite and segregated into three sizes for Cold Spray deposition. Heat treatment (HT) significantly increased deposition efficiency (DE) from 20 % to nearly 100 %. Mechanical properties (hardness, scratch) and electrochemical corrosion tests were conducted to evaluate inter-splat bonding. Performance tests revealed that as-received (AR) powder deposit exhibited superior properties, albeit with a low DE. Among HT powders, the coarser size exhibited better inter-splat bonding due to particle size and surface oxide of the powder. The AR powder's enhanced performance is linked to a novel densification mechanism.

A purine derivative for the modulation of the corrosion behavior of nickel aluminum bronze in seawater: a comprehensive and in-depth investigation on the corrosion inhibition mechanism

6-mercaptopurine (SMP), recognized for its biological activity, is investigated for its corrosion inhibition mechanism on nickel-aluminum bronze (NAB) in seawater, demonstrating a high efficiency of 99.6%. The physical adsorption of SMP on the NAB surface contributes to the multilayer structural arrangement of SMP. The Cu+-SMP complex is generated on the surface of NAB, which possesses a corrosion protection effect. SMP alters the semiconductor properties of corrosion product layer and reduces the carrier concentration. SMP can adsorb better on uncorroded NAB surfaces. This study holds significant importance in unraveling the mechanisms behind the corrosion behavior of NAB surfaces regulated by SMP.

The influence of aluminum content on thermal properties of copper-aluminum alloys: a first-principles calculation

Abstract Copper-aluminum alloy, also called aluminum bronze, is a type of host material for abradable sealing coatings. The amount of aluminum content obviously affects the properties of the coating. This research uses the density functional theory to calculate the properties of an aluminum bronze with different aluminum content. The copper-aluminum alloy model uses the model of special quasirandom structures (SQS). The elastic constant, melting point, constant pressure specific heat capacity, and thermal expansion coefficient of the copper-aluminum alloys were calculated using the quasi-harmonic approximation (QHA) method. The copper-aluminum alloys with three different nominal components were prepared using vacuum induction melting. The melting point, thermal expansion coefficient, and specific heat capacity of the copper-aluminum alloys were characterized through experiments. The results showed that the melting point of the copper-aluminum alloys decreased with an increase in aluminum content. Additionally, the coefficient of thermal expansion of the copper-aluminum alloy increased with the increase in aluminum content. Furthermore, the specific heat capacity of the copper-aluminum alloy initially increased and then reached a turning point when the β’ phase was generated. The experimental values conform well to the calculated values.

Additively Manufactured Nickel Aluminum Bronze via Laser Powder Bed Fusion Shows Excellent Anticorrosion

Additively Manufactured Nickel Aluminum Bronze via Laser Powder Bed Fusion Shows Excellent Anticorrosion

Influence of CMT welding parameters on microstructural and properties investigation of dissimilar weld joint for aluminum bronze and carbon steel

Cold Metal Transfer (CMT) welding technology has improved the appearance of weld beads and revolutionized the welding of thicker materials and dissimilar metals with precise metal deposition and reduced heat input. Cold Metal Transfer welding is predominantly used in a variety of industry applications, including aerospace, shipbuilding, automotive and marine industries. In this study, aluminum bronzes and carbon steel were joined by using CMT welding, a variant of the Gas Metal Arc Welding process, with ERCuAl-A2 as the filler metal. Optical microscopy was used to examine the microstructure of the CMT weld joint between aluminum bronze and carbon steel. Results have indicated that dissimilar metals such as aluminum bronze, and carbon steel could be successfully joined by CMT under various processing parameters. The tensile and bending strengths of the dissimilar joint were 490 MPa and 822 MPa, respectively. A variety of intermetallic compounds and solid solutions were generated in the weld zone and fusion zone. The micro-hardness in the carbon steel side of the fusion zones increased sharply, which was 164 HV in the welded condition. The dissimilar joint was stronger than the carbon steel, as the ductile fracture occurred on the carbon steel during the transverse tensile test of the welded specimen. The microstructure interpretation of welded dissimilar joints was analyzed by scanning electron microscopy and transmission electron microscopy.

Synergistic improvement of erosion-corrosion resistance and mechanical properties of nickel aluminium bronze alloy by the addition of Cr

Synergistic improvement of erosion-corrosion resistance and mechanical properties of nickel aluminium bronze alloy by the addition of Cr

Fatigue life of S960 high strength steel with laser cladded functional surface layers

This study evaluates the fatigue life of S960 high-strength steel with laser-cladded layers of aluminium bronze, hard chrome, cobalt alloy, and stainless steel, using three-point bending tests. Our results demonstrate that while these cladded layers offer potential for enhanced surface properties, they generally reduce the material’s fatigue life due to alterations in the heat-affected zone and the introduction of microstructural defects at layer interfaces. The extent of fatigue life reduction varies with the type of cladded layer, highlighting the importance of optimizing laser cladding parameters to minimize detrimental effects and improve component longevity.

Microstructural transformation and corrosion–cavitation behavior of ultrasonic nanocrystal surface modified nickel aluminum bronze (NAB)

In this study, nickel–aluminum bronze (NAB) is optimized by ultrasonic nanocrystal surface modification (UNSM), and its surface microstructural evolution, surface hardness, electrochemical corrosion behavior, and cavitation erosion behavior are investigated. The potentiodynamic polarization curves and electrochemical impedance spectra before and after UNSM treatment of NAB are measured using a typical three-electrode system. The cavitation erosion process is simulated through the vibration of ultrasonic waves underwater, and the cavitation erosion resistance performance of various specimens is evaluated. UNSM significantly refines the coarse and heterogeneous multi-phase structure of the cast NAB, providing a relatively uniform and dispersed structure. Simultaneously, severe plastic deformation rapidly increases micro-strains on the NAB surface, which effectively improves its surface hardness from 211 to 360 Hv. After UNSM treatment, the corrosion potential increases slightly; and the passivation potential and current decrease considerably, dropping from 207 to 103 mV and from 5.23 to 2.41 mA/cm2, respectively. This is primarily because of the slowdown of selective-phase corrosion and the uniform formation of an oxide film. Additionally, UNSM parameters affect corrosion potential by regulating surface roughness. A smoother surface corresponds to a higher corrosion potential at the same load. UNSM treatment significantly improves the cavitation corrosion resistance of NAB, primarily because an increase in hardness and uniform distribution of structure effectively slows the speed of crack formation and propagation, which is a result of the synergistic improvement of mechanical and corrosion resistance properties.

Fatigue response of wire-arc additive manufactured nickel-aluminum bronze (NAB) in the post-annealed condition

Nickel-aluminum bronze (NAB) is chosen for critical applications like marine propellers, pump components, and offshore structures due to its exceptional mechanical properties and corrosion resistance. Considering the utmost importance of the fatigue performance of NAB in such applications, this study investigates the fatigue performance of wire arc additive manufactured (WAAM) NAB in the annealed (675 °C for 6 h then furnace cooling) condition. To this end, static mechanical properties were evaluated using uniaxial tensile testing, while fatigue properties were assessed through fully reversed tests conducted at ambient temperature. Electron backscatter diffraction (EBSD) was utilized for the examination of the texture, and grain size distribution in annealed WAAM NAB. Additionally, scanning electron microscopy was employed to inspect fatigue-fractured specimens, while the analysis of EBSD was conducted to examine the deformation behavior beneath the crack initiation zone. The results provide insights into the fatigue life, crack initiation, and propagation characteristics of WAAM NAB relative to the cast counter material. The findings of this research provide valuable insights into the mechanical properties, microstructural characteristics, and fatigue response of WAAM NAB, informing the design of fatigue-resistant components and supporting the reliable utilization of WAAM NAB in demanding applications such as the marine and naval industries.

The mechanism of recrystallization of binary aluminum and tin bronzes

A nanostructural mechanism for recrystallization of binary aluminum and tin bronzes has been developed. First, structure-forming nanocrystals of α-phases, β-phases and γ-phases are formed from elementary nanocrystals of copper, aluminum, tin and their free atoms. The crystallization centers of microcrystals of phases are formed from them. From these centers, structure-forming nanocrystals of phases, free atoms of copper, aluminum, tin, microcrystals of α-phases, β-phases and γ-phases of binary aluminum and tin bronzes are formed.

Machine learning in prediction of residual stress in laser shock peening for maximizing residual compressive stress formation

Laser Shock Peening (LSP) is an advanced technique for enhancing surface properties, drawing significant interest for its ability to induce beneficial residual stresses in materials. Traditional LSP design processes, reliant on manual parameter selection, often result in imprecise control over the stress distribution, necessitating multiple iterations and high costs. This study introduces a machine learning (ML)-based approach, utilizing the Random Forest (RF) algorithm, to automate and optimize the design of LSP parameters for nickel-aluminium bronze surfaces. Our findings demonstrate the RF model’s capability to accurately predict and optimize residual stress distributions, achieving compressive stresses up to 472 MPa with a notable reduction in design iterations. The model forecasts both uniform and non-uniform stress patterns, particularly identifying areas susceptible to Residual Stress Holes (RSH) with improved precision. With an Absolute Percentage Error (APE) of only 6.2 %, our approach significantly outperforms traditional ML algorithms, offering a novel method for efficiently designing complex residual stress fields in LSP applications.

Elucidating different selective corrosion behavior of two typical marine aluminum bronze alloys from the perspective of constituent phases

The selective corrosion behavior of two typical marine aluminum bronze alloys (i.e., NAB and MAB) were investigated comparatively. The characteristics of each constituent phase in NAB and MAB including composition, morphology, distribution and work function were analyzed, and their roles in the micro-corrosion behavior were elucidated. MAB exhibits de-alloying corrosion, whereas NAB shows localized selective phase corrosion. The crucial factor causing different selective corrosion behavior is the morphology and distribution of constituent phases. The results reveal correlations between selective corrosion behavior and microstructure and provide insights into improving corrosion resistance of aluminum bronze alloys on the concept of microstructure tailoring.

Influence of the bronze powder filler on the adhesion of epoxy compound to aluminum bronze

Influence of the bronze powder filler on the adhesion of epoxy compound to aluminum bronze

Toward Reducing Casting Defects via 3D Risers via 3D Sand-Printing: A Simulation Study

AbstractThe 3D sand printing (3DSP) process is a binder jetting class of additive manufacturing process that can incorporate complex 3D mold designs and consolidate cores with intricate features that were previously inaccessible. Prior studies in 3DSP mold design have been shown to improve pouring and filling conditions for sand casting. However, the opportunity to improve casting quality by exploring 3D riser designs during the solidification stage has not yet been explored. In this research, three novel 3D riser geometries—ellipsoid, spherical, and a fusion riser (combination of cylindrical and ellipsoid riser) were investigated. The results were compared to the benchmark cylindrical risers to assess casting performance (e.g., reduction in shrinkage porosity, increase in solidification time). Computational solidification simulations have been presented to evaluate the characteristics of the novel risers for three different metal alloys- nickel aluminum bronze (NAB), low-carbon steel A216 (WCB), and aluminum alloy (A319) alloy. From the results of this research, spherical risers were found to provide 45% yield improvement of for the three alloys studied. In addition, the riser neck diameter using a spherical riser experienced up to 77% reduction when compared to the recommended dimensions from previous literature. Finally, one of the spherical riser designs provided 18% improvement in terms of riser-pipe safety height over the benchmark design. Findings from this research will help metalcasting industries to optimize their riser designs for complex casting geometries by implementing 3D riser geometries (via 3DSP) into traditional mold making for yield improvement and defect-free castings.

Directed energy deposition of aluminium bronze/GNPs composites: Microstructural evolution for enhanced wear resistance

The enhancement mechanism of graphene on the wear resistance of Aluminium Bronze alloy powder was investigated using the DED technique. The incorporation of GNPs enhanced convection in the melt pool, which resulted in a tighter bonding of the substrate to the deposited layer. Aluminium Bronze/GNPs undergo a phase transition compared to the pure material. The phase transition leads to the generation of a large number of twinned crystals. The incorporation of GNPs resulted in a 56.38% increase in hardness. Under loads of 120 N, 150 N, and 180 N, the friction coefficients decreased from 0.28, 0.23, and 0.51 to 0.31, 0.27, and 0.26, respectively. Additionally, the wear mass became 42.86%, 62.50%, and 93.87% of the corresponding load conditions.

Role of oscillation frequency and amplitude on the microstructure and properties of linear friction welded nickel aluminium bronze joints

This study explores the influence of oscillation frequency and amplitude on the quality of linear friction welded joints using as-cast nickel aluminium bronze. Welding was conducted at 30 Hz, 50 Hz, and 70 Hz oscillated frequencies and amplitudes of 1.5 mm, 2 mm, and 3 mm. The joint’s performance was thoroughly investigated through systematic analysis, including macrostructure examination, peak interfacial temperature measurement, microstructure evaluation, strain assessment, cooling rate determination, microhardness testing, and tensile property characterization. The width of the weld zone varied from 183 μm to 297 μm, and the thermomechanical affected zone (TMAZ) area ranged from 4.48 mm2 to 14.79 mm2 across different process parameters. In the parent material, the volume fraction of the β-phase was as low as 20.2%, contrasting with the dominant α-phase at 79.8%. The average grain size of the lamellar and globular α-phase mixture was 26.4 μm. Notably, the weld zone exhibited extremely refined α-phase grains, with diameters less than 5 μm in all cases. The volume fraction of the β‘-phase increased significantly with higher frequencies, from 15.299% at 30 Hz to 26.98% at 50 Hz, peaking at 40.08% at 70 Hz, leading to varying k phases. This variation in microstructure had a substantial impact on mechanical properties. Tensile strength ranged from 503 MPa to 582 MPa, while ductility varied from 13.5% to 21.7%. Additionally, the hardness of the parent material increased from approximately 155 Hv to 260 Hv. This study demonstrates that controlling the oscillation frequency and amplitude in linear friction welding processes can yield consistent, high-quality welds in nickel aluminium bronze.

Effect of heat input on bead geometry and mechanical properties in wire arc additive manufacturing of a nickel aluminum bronze alloy

Wire arc additive manufacturing (WAAM) stands as an efficient and cost-effective method for producing large-scale engineering components while minimizing waste. This study explores the influence of WAAM process parameters on nickel aluminum bronze (NAB) parts, focusing on the wire feed rate (WFR) as a key factor governing heat input and its effects on bead geometry, microstructure, and mechanical properties. The investigation involved depositing a single bead from NAB alloy while varying the WFS within the 2–7 m/min range, resulting in heat inputs ranging from 20.600 to 57.960 kJ/m. The results revealed that increasing heat input up to 34.944 kJ/m led to an augmentation in the bead dimensions and increased hardness due to κ-precipitates formation within the α-Cu matrix. However, with further increments in heat input to 49.088 kJ/m and 57.960 kJ/m, the bead dimensions and hardness exhibited a decline as the uniformity of intermetallic κ distribution lessened. Through optimization of WAAM process parameters, a defect-free single-wall NAB was successfully manufactured with enhanced properties. The tensile strength along the horizontal direction for the single-wall NAB alloy was found to be superior to that of the vertical direction, irrespective of the specimen's extraction regions. Additionally, the bottom specimen exhibited slightly higher tensile strength than the center and upper specimens due to being the initial layers of the wall deposited on the substrate plate, undergoing a faster cooling rate. These findings underscore the potential of WAAM as a robust method for the fabrication of larger NAB components with precision and efficiency.