Aluminum Bronze Research Articles

Determination of the geometric parameters of the defects based on the tomographically obtained data and their influence on the fatigue behavior of the S960 with laser cladded protective layers

This article deals with identifying defects of layered high strength steel materials with the help of tomography measurement. Test samples were made of S960 High Strength Steel to which layers of either aluminium bronze, hardchrome, cobalt alloy or stainless steel were applied by a laser cladding technology. The experimental campaign included a study of morphometric parameters of internal defects in and near the bi-material interface region using X-ray micro-tomography and their potential influence on the fatigue behavior during a three-point bending test.

An Investigation of Thermomechanical Behavior in Laser Hot Wire Directed Energy Deposition of NAB: Finite Element Analysis and Experimental Validation

Laser Hot Wire (LHW) Directed Energy Deposition (DED) Additive Manufacturing (AM) processes are capable of manufacturing parts with a high deposition rate. There is a growing research interest in replacing large cast Nickel Aluminum Bronze (NAB) components using LHW DED processes for maritime applications. Understanding thermomechanical behavior during LHW DED of NAB is a critical step towards the production of high-quality NAB parts with desired performance and properties. In this paper, finite element simulations are first used to predict the thermomechanical time histories during LHW DED of NAB test coupons with an increasing geometric complexity, including single-layer and multilayer depositions. Simulation results are experimentally validated through in situ measurements of temperatures at multiple locations in the substrate as well as displacement at the free end of the substrate during and immediately following the deposition process. The results in this paper demonstrate that the finite element predictions have good agreement with the experimental measurements of both temperature and distortion history. The maximum prediction error for temperature is 5% for single-layer samples and 6% for multilayer samples, while the distortion prediction error is about 12% for single-layer samples and less than 4% for multilayer samples. In addition, this study shows the effectiveness of including a stress relaxation temperature at 500 °C during FE modeling to allow for better prediction of the low cross-layer accumulation of distortion in multilayer deposition of NAB.

Natural Seawater Impact on Crack Propagation and Fatigue Behavior of Welded Nickel Aluminum Bronze

ABSTRACTNickel aluminum bronze (NAB) is a complex alloy used extensively in the marine environment. Fatigue strength of NAB is reduced by welding and prior seawater corrosion. This study investigated the combined effect of corrosion and plasma welding on the fatigue behavior of NAB. Natural seawater corroded samples were used in tension‐tension cyclic loading tests to observe fatigue crack initiation, propagation, and failure. Fatigue cracks initiated from corrosion pits at the weld toe. Stress corrosion and fatigue cracks propagated along the path of β′ and κIII phases. A short crack growth model (SCGM) predicted fatigue strength using experimentally obtained material properties and corrosion pit dimensions. Model predictions were used to develop S‐N curves and were within 30% of experimental results. The SCGM produced accurate and reliable fatigue life results that could be applied by industry to aid in revalidation decision making and inspection scheduling.

Corrosion of Copper, Cupronickel, Nickel Aluminium Bronze and Super-Duplex Stainless Steel Rotating Cylinder Electrodes in Seawater under Turbulent Flow Conditions

The corrosion of uncoated metals in a marine environment restricts the choice of suitable engineering metals and alloys. Anodic dissolution of metal and cathodic reduction of oxygen are important processes and formation of a surface oxide film can affect both electrode reactions. Charge transfer and mass transfer data can provide information on corrosion rate and mechanism. Several metals and alloys having a history of use in marine engineering are considered, including copper, two copper alloys (cupronickel and nickel aluminium bronze) plus a more recent addition to strong, corrosion resistant alloys (a super duplex stainless steel). The rotating cylinder electrode offers the benefits of a controlled, turbulent flow of electrolyte, facilitating controlled mass transfer in a compact cell geometry which is well-suited to bench-top operation. These features are illustrated using a variety of electrochemical techniques, including open-circuit potential vs time monitoring, linear sweep voltammetry, rotation speed step- or potential step current transients and linear polarisation resistance measurements. Seawater taken from Langstone Harbour, Hampshire, UK, was filtered, air-saturated, pH 8.0 and maintained at 25 °C. Dimensionless group correlations and graphical plots (using an analogous approach to the Koutecky-Levich equation for an RDE) enabled contributions of charge transfer-, mixed- and mass transfer- controlled data to be appreciated, allowing the Tafel slopes of electrode reactions, the diffusion coefficient of dissolved oxygen, the mass transfer coefficient for oxygen reduction and the mean corrosion rate to be estimated.

The role of coherent nano precipitates on stacking fault and deformation twin formation during tensile deformation of wire arc additive manufactured nickel-aluminum-bronze

The strain hardening mechanisms and dislocation interactions of a wire arc additively manufactured (WAAM) nickel-aluminum-bronze (NAB) alloy was investigated using multi-scale characterization approach cross-correlating scanning electron microscopy (SEM), SEM-based electron back-scatter diffraction (EBSD), site- and crystallographic orientation-specific focused ion beam (FIB) nanofabrication, scanning transmission electron microscopy (STEM) and STEM-based energy dispersive X-ray spectroscopy (EDS). Flat, rectangular dog bone specimens were strained under uniaxial tension conditions. To understand the micro- and nanometer scale deformation mechanisms throughout the microstructure, tensile test specimens were interrupted near the yield strength and ultimate tensile strength. STEM microstructural characterization revealed that tensile deformation occurs by planar slip and multiple slip bands interacting on different {111} planes as well as the nucleation of dislocations from the interfaces associated with grains and secondary phase particles. To the authors knowledge for the first time the Center of symmetry (COS) analysis revealed that in both samples the shearing of nanoscale precipitates led to the formation of extended stacking faults including a combination of intrinsic stacking faults and 2-layer extrinsic stacking faults. At high strain levels more dislocations and stacking faults were nucleated, as well as intersecting slip bands further facilitating the activation of the stair-rod cross-slip mechanism and thickening of an ESF to create a 3-layer nano-twin. Activated mechanisms of plastic deformation and associated role of the precipitates are discussed with respect to the microscopic strength-plasticity characteristics as well as macroscopic mechanical properties of WAAM NAB alloy.

Effect of applied load on adhesive wear and corrosive wear behaviours of two aluminium bronze (Cu-Al-Fe) alloys

Effect of applied load on adhesive wear and corrosive wear behaviours of two aluminium bronze (Cu-Al-Fe) alloys

Method for Processing Images of Aluminum Bronzes with a Dispersed Microstructure

Method for Processing Images of Aluminum Bronzes with a Dispersed Microstructure

Capillary interaction of copper melt with dense and porous MAX phase (Cr, Mn)2AlC

In the present work, we experimentally studied the interaction of a pure copper melt with a dense MAX-phase (Cr, Mn)2AlC after sintering by the electric pulse plasma method and a porous phase obtained by pressing at room temperature. The porous phase (20 % porosity) absorbs molten copper at temperatures above 1200 °C; the kinetics of absorption was directly measured using high-speed thermal and video cameras. The experiments were carried out in a vacuum of 10–3 Pa. Studies using scanning electron microscopy, EDX spectral analysis and X-ray diffraction have shown that a chemical interaction of the MAX-phase with a copper melt occurs with the formation of a solution of aluminum and chromium in copper and the decomposition of the MAX-phase to chromium carbides (stable or metastable). The dense, sintered sample also actively interacts with the melt, although the contact angles exceed 100°. The difference between porous and dense samples lies in the kinetics of interaction. The results were compared with experiments on wetting the Cr2AlC MAX-phase with a Cu (0.8 at.% Cr) melt conducted earlier. The described experimental conditions and the results of determining chemical and phase changes in the process of capillary interaction indicate the possibility of creating a composite material with a submicron structure of chromium carbide impregnated with aluminum bronze.

The influence of ultrasonic vibration on micro-arc oxidation behaviour of manganese aluminium bronze

As a promising material for marine engineering, the insufficient corrosion resistance of manganese aluminium bronze (MAB) alloy when exposed to the marine environment may limit its application. In the present work, micro-arc oxidation (MAO) of MAB alloy was conducted in an aluminate-based electrolyte with the influence of ultrasonic vibration (UV) examined. A porous ceramic film has been successfully produced on MAB via MAO, which exhibits dramatic increases in both film thickness and compactness after the introduction of UV. As a result, the ceramic film produced by ultrasound-assisted MAO (UMAO) exhibits an enhanced corrosion resistance relative to that via MAO, which also possesses a desired antifouling capability. Hence, the present work illustrates the influence of UV on the MAO behaviour of non-valve alloys and, more importantly, provides theoretical guidance for related surface modification strategies in marine engineering.

Коррозионные характеристики композитов БрАМц9-2/06Х18Н9Т, полученных двухпроволочным электронно-лучевым аддитивным производством

Introduction. The development of novel materials based on copper alloys and stainless steel, as well as the determination of the optimal parameters for its processing make it possible to expand the area of its implementation, increase efficiency and service life of tools and constructions. The load-bearing parts of marine equipment (bearing constructions, piston cylinders, pumps, valves, gears, rotary instruments, etc.), made of austenitic steels or aluminum bronze, are in direct contact with sea water, so the problem of increasing its corrosion resistance in the presence of strong oxidizing agents (Cl-, F- anions) is relevant. One of the advanced and actively researched methods for producing copper/steel composites is additive manufacturing that allow fabricating complex parts through layer-by-layer growth. In particular, the synthesis of composites based on aluminum bronze and steel can be realized by wire-feed electron beam additive manufacturing. In order to implement composite materials produced via additive technologies in a humid (marine) climate, it is necessary to ensure not only high strength, but also corrosion properties. The purpose of this work is to study the corrosion resistance of composites, based on aluminum bronze CuAl9Mn2 and stainless steel ER 321 produced by dual-wire-feed electron beam additive manufacturing. Research methods. Examination of the surface of CuAl9Mn2/ER 321 composites before and after corrosion tests was carried out by methods of voltammetry and electrochemical impedance spectroscopy using a potentiostat-galvanostat. Results and discussion. Using a complex of electrochemical methods, it is revealed that the developed composites with a volume fraction of steel ≥ 25% demonstrate a significant decrease in anodic current densities and a simultaneous increase in charge transfer resistance. Composites with a steel content of 75 vol. % are characterized by the highest corrosion properties in 3.5 wt. % NaCl solution, which is referred to a reduction in corrosion rate by 9.5 times compared to aluminum bronze. It is shown that the main processes occurring on the surface of the composites (CuAl9Mn2 + ER 321) are anodic oxidation of copper and iron, leading to the formation of corrosion products – Cu2O and FeCl2.

Formation of Ultra Fine Grained Microstructure in Aluminum Bronzes of the Cu-Al, Cu-Al-Si, and Cu-Al-Si-Mn Systems After Electron Beam Additive Manufacturing

Formation of Ultra Fine Grained Microstructure in Aluminum Bronzes of the Cu-Al, Cu-Al-Si, and Cu-Al-Si-Mn Systems After Electron Beam Additive Manufacturing

Additive manufacturing nickel-aluminum bronze alloy via wire-fed electron beam directed energy deposition: Enhanced mechanical properties and corrosion resistance compared to as-cast counterpart

In the present work, a wall-structured nickel-aluminum bronze (NAB) alloy was fabricated via electron beam directed energy deposition (EB-DED) additive manufacturing with a single-pass multi-layer deposition strategy. A comprehensive comparative analysis of microstructure, mechanical properties, and corrosion resistance was conducted against a conventionally cast NAB alloy. The inherent rapid solidification and cyclic thermal processing of the EB-DED technique profoundly influenced the microstructural evolution of the NAB alloy. The as-deposited NAB alloy exhibited a fine-grained microstructure, devoid of the martensitic β′ phase, accompanied by the spheroidization of partial κIII precipitates, and a homogeneous distribution of alloying elements. These distinctive microstructural attributes synergistically enhanced the strength, hardness, and toughness of the NAB alloy, conferring superior mechanical properties compared to its cast counterpart. Furthermore, the as-deposited alloy demonstrated remarkable corrosion resistance in a 3.5 wt% NaCl solution, significantly outperforming the cast alloy. The underlying mechanisms governing the structure-property relationships were elucidated. This comprehensive investigation provided insights into the unique characteristics and potential applications of EB-DED fabricated NAB alloys, positioning them as promising candidates for high-performance components subjected to severe mechanical and corrosive service conditions.

Effect of Shot‐Peening Process and Nanoparticle‐Added Lubricant on the Tribological Performance of Aluminium‐Based Sliding Bearing Material

ABSTRACTIn this study, it is aimed to increase the wear and fatigue performance of aluminium‐based sliding bearing material by using silver nanoparticles (AgNPs) added lubricant and shot‐peening process. The main purpose is to minimise the wear of the bearing material by penetrating AgNPs added lubricants into the rough surfaces formed by shot peening. Almen intensity, coverage and shot size parameters in the shot‐peening process were analysed in terms of hardness, surface roughness and fatigue strength. The shot‐peened aluminium bronze was subjected to wear experiments under dry, pure water and AgNPs added lubricant conditions. The wear test results were analysed in terms of friction coefficient, wear volume and surface roughness parameters, and the interaction of lubricant and shot‐peening parameters was evaluated. According to the results of the shot‐peening experiments, the Almen intensity was the most effective parameter in terms of hardness and surface roughness (91.62%). It was concluded that the hardness value was 8% higher at high Almen (12–14A) intensity compared with low Almen intensities, and the shot‐peening process could increase the fatigue strength by ~21 times. According to the wear tests, the most effective parameters were 4–6 Almen intensity and AgNP‐added lubricant.

Optimization design and interface characteristics research of high damping NiTi - Nickel-Aluminum Bronze functional gradient composite coating additively manufactured by high-speed laser-directed energy deposition

The near-equatomic NiTi shape memory alloy demonstrates exceptional damping performance due to its distinctive low-temperature self-cooperative martensitic internal friction. This study successfully fabricated NiTi-NAB (Nickel-Aluminium bronze shape memory alloy) functionally graded composite coatings with excellent metallurgical bonding between layers on Q235 steel substrates by designing an appropriate interlayer structure and employing the high-speed laser-directed energy deposition (LDED). Through comprehensive evaluation of the composite coating's performance and the numerical simulations of heat transfer within the molten pool, we elucidated the impact of process parameter levels on the microstructure and phase transformation characteristics of the NiTi alloy coating (NTC). The phase composition and phase interface characteristics of the NTC surface and bonding interface were analyzed using an electron probe microanalyzer and transmission electron microscopy, while dynamic thermomechanical analysis was employed to evaluate the damping performance of the NTC. The results indicate that an optimal parameter combination area still exists within the NTC-LDED process parameter window, even with equal laser energy density. Insufficient parameter levels can lead to an increase of micro-defects within the NTC, consequently causing a deterioration in both the cohesion and deformation resistance of the coating. Excessively high parameter levels can lead to significant element loss and residual stress, which in turn contributes to an increase in microcracks within the coating. A considerable quantity of reaction product mixture phases was formed at the interface between NTC and NAB, tending to align coherently with the NAB phase interface. The NTC, prepared with optimal process parameters, exhibits exceptional damping performance with a damping ratio of 0.498 at internal friction equilibrium, rendering it highly promising for applications in surface erosion protection for fluid machinery.

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.