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Among the various types of recently released composite materials, particle-reinforced metal matrix composites (MMCs), in particular aluminum as the matrix material, have been shown to provide substantial industrial benefits in the automotive and aerospace sectors. The current research focused on the corrosion behavior of an Al7075 hybrid composite in 0.1 M hydrochloric acid (HCl) and 3.5% NaCl media at different temperatures. Electrochemical techniques, such as Tafel polarization (TP) and electrochemical impedance spectroscopy (EIS), were employed to study the corrosion behavior in the respective solutions. The results showed that the corrosion rate of the studied specimen increased from 31.77 to 47.61 mmy−1 in 0.1 M HCl and from 0.26 to 1.28 mmy−1 in 3.5% NaCl with increasing temperature. The corrosion current density of the Al7075 hybrid composite in 0.1 M HCl is on the order of 10−3 Acm2, and that in 3.5% NaCl is on the order of 10−5 Acm2. This confirms the increased rate of composite corrosion in the 0.1 M HCl medium compared to that in the 3.5% NaCl medium. A suitable mechanism was proposed for the corrosion of the Al7075 hybrid composite in both media.

Friction stir welding is an advanced method of joining various metals and alloys in the aircraft and mechanical engineering industries. This type of welding is used to join materials that are difficult to weld or not weldable by conventional methods. The high-strength D16 aluminum alloy is difficult to weld by fusion, which is associated with the formation of a dendritic structure in the fusion zone leading to a decrease in the mechanical strength of the joint. In the work, the microstructure and microhardness of a welded seam of the D16 aluminum alloy produced by friction stir welding was studied. Using scanning electron microscopy and optical metallography, the authors identified the presence of three zones: the weld core, the thermomechanical impact zone, and the heat effected zone. In the central part of the welded joint (in the core), a laminated onion ring structure was discovered. A change in the chemical composition of the aluminum solid solution was identified in different areas of the weld zones, as well as the presence of a concentration gradient within each zone. In the upper part of the welded seam, the solid solution is silicon-enriched and depleted in copper. Due to the solid solution depletion in alloying elements, the aluminum content in the solid solution in the zone of the welded joint is higher compared to the initial state. The microhardness values in different areas of the welded joint correlate with changes in the chemical composition. In the welded joint zone, a significant decrease in microhardness was found compared to the initial state, and a change in microhardness associated with the chemical composition gradient within each zone was also observed.

The thermal properties of the aluminum EN AW-2024 alloy (duralumin) delivered in the T3 condition (solution annealed, quenched, cold-deformed, and naturally aged) were experimentally investigated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), and light flash apparatus (LFA) for thermal diffusivity and thermal conductivity evaluation. The microstructure of the alloy in the initial state and after heating to 400?C was investigated by scanning electron microscope (SEM) and energy-dispersive spectroscopy. The presence of an exothermic thermal effect in the temperature range from 230 to 283?C during the first heating of the examined sample was determined by the results of DTA/DSC analysis. The thermal diffusivity of the investigated alloy was measured in the temperature range from 25 to 400?C using three heating runs. During the first heating, the thermal diffusivity of the investigated alloy increased with an increase in temperature up to approximately 300?C, after which it decreased. During the second and third heating, it was observed that the measured thermal diffusivity values at temperatures lower than 300?C were significantly higher than during the first heating, and the thermal diffusivity gradually decreased with increasing temperature in the entire investigated temperature range. Experimentally determined thermal diffusivity and density, as well as calculated specific heat capacity data, were used to determine the thermal conductivity of the studied alloy in the temperature interval from 25 to 400?C. The obtained results indicate that initial heating to a temperature above 300?C causes a significant increase in the values of the thermal diffusivity and thermal conductivity of the investigated 2024-T3 alloy. [ABSTRACT FROM AUTHOR]

Heat treatment conditions are chosen in accordance with alloys and production method of blanks and parts made from them. The heat treatment of parts produced from aluminum alloys is based on the fact that, as the temperature decreases, the solubility of many elements in solid aluminum deceases. The aim of the present study is to investigate the effect of heat treatment conditions of a wrought aluminum alloy on its structure and properties and, based on the data, to choose more rational technological heat treatment conditions. [ABSTRACT FROM AUTHOR]

Ludwig Loewy was a Jewish engineer who left Nazi Germany in 1936 to set up an engineering firm in London as a refugee. Britain was rearming, and a new generation of aircraft was being developed based on light alloy construction. The new Loewy Engineering Company had the expertise to supply presses and rolling mills required for alloy fabrication, which were otherwise supplied from Germany at a time of growing tension. The new firm also built a giant tube press for steel for the Admiralty. Loewy's new company grew rapidly in London, helped by a workforce of refugee engineers and managers and 'many thousands' of machinery drawings from Germany. Loewy became a technical advisor to the British Government's production programme for aircraft until his death in 1942. Back in Germany, Loewy's former firm, Schloemann in Düsseldorf, was Aryanised after his departure. Schloemann continued to supply equipment into the UK until the outbreak of war and went on to help the German and Italian war effort. Ludwig was dispossessed of his major share in the Company, and the history of Schloemann was rewritten. Ludwig Loewy's rapid assimilation owed much to earlier contacts with the UK engineering and metals establishment, his expertise in a sector that was growing rapidly and short of skills, customers who needed his technology, and his own personal energy and drive. The Government welcomed his contribution to aircraft and warship production at a time of break-neck rearmament. Ludwig Loewy's experience supports the view that German-speaking refugee engineers were readily accepted in the UK from 1933 to 1945. [ABSTRACT FROM AUTHOR]

This study aims to control the characterization and mechanical properties of smelting Al-Cu Alloy through Hold-Melt Time. This research uses aluminum scrap and copper wire scrap to produce quality as-cast ingots, clean the environment, and increase waste utilization. Copper melting point of 1083 °C is immersed in molten aluminum at a temperature of 900 °C for 10-30 minutes causing copper to dissolve in aluminum due to smelting events based on diffusion phenomena. Parameters of temperature and immersion time of copper in molten aluminum in this study are expressed by hold-melt time. In the copper aluminum alloy trade, commonly called Duralumin, it is commonly used for impact loads and is heat-treatable. Resistance to cryogenic temperatures, in the future Duralumin has the potential to replace stainless steel. This study used an electric resistance furnace with the specifications for smelting aluminum 3 kg, electric power 2.5-3.0 kW, electric voltage 220 Volts, maximum temperature 1000 °C. It had been conducted an experiment where copper had been melted under its melting point in duralumin ingot casting. In this study, copper pieces were soaked in liquid aluminum with temperature of 900 °C. After 10-30 minutes of holding melt, the soaked copper became Al-Cu alloys and was called molten Duralumin. After the molten duralumin had been cleaned from dross, it was poured into ingot casting. From specific weight test, more soaking time of the copper in liquid aluminum caused specific weight of ingot duralumin increase from 47.08 % to 57.56 % and its hardness increase from 93 to 113 BHN. This study contributes on melting energy saving and improves the characteristic and hardness of ingot aluminum type 2xxx. [ABSTRACT FROM AUTHOR]

Almost 85 years have passed since the development of Al-Zn-Mg-Cu Extra Super Duralumin in Japan in 1936. This alloy was developed by Dr. Igarashi in response to the Japanese Navy's order to Sumitomo to develop an alloy with tensile strength of 588 MPa (60 kg/mm²) or higher, exceeding Alcoa's super duralumin 24S. This alloy was then adopted for use in the Zero fighter. Based on this alloy, Alcoa's 75S was developed in 1943. This paper describes the history of the development of Extra Super Duralumin, starting with Duralumin. The paper also discusses the issues that are considered important for the future development of the aluminum alloys based on the historical review and our study. One is the relationship between quench sensitivity and age-hardening properties of AlZnMg alloys and the second is the occurrence of shear fracture in the Al-Zn-Mg-(Cu)-Zr alloys. This is the points to be noted in the development of high strength and high toughness Al-Zn-Mg-Cu alloys. [ABSTRACT FROM AUTHOR]

A study is performed of the biocorrosion of D16T duralumin. A mechanism of biocorrosion is proposed in which the initiators of corrosion damage of the alloy D16T are reactive oxygen species produced by microscopic fungi. It is proposed that hydrogen peroxide, which forms due to the activity of micromycetes and the activation of oxygen by zero-valent aluminum (ZVA1) participates in the biocorrosion of D16T alloy. Mechanisms of the intergranular, pitting, and ulcerative corrosion of duralumin are revealed that result from interaction between the metal and micromycetes. [ABSTRACT FROM AUTHOR]

MIDC’s researchers in fulfilling Industry Development Programme have taken a step to develop technology in the design application of orthopedic implants to help suppress the rate of imported medical devices in Indonesia. This research objective was to make a prototype plate for a jawbone connector that meets the geometric specifications with the metal injection molding approach. The jawbone connector plate has a very small size of about 2 mm x 20 mm x 0.5 mm that needs precision mold with certain geometric specifications. MIM approach was used, from the literature reviews that show MIM is the appropriate process for manufacturing implants. The phases of MIM were done according to the standard reference which is making raw materials or feedstock, gatting system design, flow simulation, precision mold producing, mold testing, injection process, debinding, sintering, and mechanical product testing. The results of this study were precision molds with several variants and were test using plastic polypropylene to see the performance of the mold. The researchers then produce the jawbone connector implant using feedstock material. The test result conducted in MIDC successfully shows that the mold can produce shapes that match the required geometry.

Presents a study which investigated the attenuation of Rayleigh surface waves by one- and two-dimensional rough surfaces on duraluminum and titanium samples. Theoretical formulations; Experimental set-up and procedure; Experimental results.

The acceleration of a flyer by a magnetic field allows studying the dynamic characteristics of matter in submicrosecond processes. At the Angara-5-1 facility, pressure is created by a magnetic field of the current with the linear current density of up to 5 MA/cm. The velocity of up to 10 km/s was obtained in the first experiments on acceleration of a duralumin flyer 1 mm thick. Two methods are used for registration of the flyer velocity: laser shadow photography and VISAR interferometric method. This paper presents the results of experiments on determining the velocity of a flyer by the VISAR method. Particular attention is paid to the problem of suppression of spurious signals in the VISAR registration system. The first problem was electromagnetic interference emerging when the Angara-5-1 facility is activated, when megavolt voltages and megaampere currents are generated within a hundred nanoseconds. The second problem was bremstrahlung radiation emerging when magnetic self-isolation is established in vacuum transmission lines. This radiation affects the optics, fiber optic cables, and photomultipliers. The suppression of these two sources of interference ensured the reliable registration of the VISAR signals. The results obtained by the two laser methods—shadow photography and VISAR—coincide with each other and with the results of numerical simulation of flyer acceleration. The experimental results and simulation results are compared. [ABSTRACT FROM AUTHOR]

In present work, both the theoretical solutions and the corresponding cropping experiments are carried out to investigate the influence of the load control strategy on bar fine cropping process. The working principle of the new proposed cropping method is detailed introduced. Five different types of the loading cycles are designed basing on it. A new proposed load control strategy with a suitable assumed constant stress intensity factor range is obtained theoretically and verified by the corresponding cropping experiments. According to a new proposed cross-section quality evaluation method, the comparative results show that the section quality and the cropping time are greatly influenced by the cropping load. The best quality is obtained by the loading cycle (iii). [ABSTRACT FROM AUTHOR]

In this research, hull structure of Ray-type Underwater Glider (RUG) that could be a next generation unmanned vehicle was studied. RUG is capable of long-term operation at higher speeds than conventional cylindrical underwater gliders due to its ray shaped body composed of dual buoyancy engine. For long-term operation, it is necessary to develop a lightweight control housing and battery case. For this reason, the carbon fiber container was used to be lighter and stronger than duralumin used in the past. Through the stress and buckling analysis, it was shown that the container was able to withstand the pressure of 200 m which is the target water depth with the safety ratio of about 1.8 times. Using a carbon composite material, the mechanical strength can be maintained while reducing the weight of the pressure vessel by more than 40% compared with the high tensile aluminum material. [ABSTRACT FROM AUTHOR]

The paper is devoted to study of the aerodynamic forces acting on flat cantilever beams performing flexural vibrations in a viscous fluid. Original method for the force evaluation is presented based on analysis of experimental measurements of a logarithmic decrement of vibrations and relative variation in frequency of duralumin test specimens. The theoretical core of the method is based on the classical theory of bending beam oscillations and quasi-two dimensional model of interaction between a beam and a gas. Using the proposed method, extensive series of experiments for a wide range of oscillations parameters were carried out. The processing of the experimental data allowed to establish the global influence of the aerodynamic effects on beam oscillations and the local force characteristics of each cross-section of the beam in the form of universal functions of dimensionless amplitude and dimensionless frequency of oscillation. The obtained estimates of the drag and added mass forces showed a good correspondence with the available numerical and experimental data practically in the entire range of the investigated parameters. [ABSTRACT FROM AUTHOR]

An electron microscope analysis of the surface of deposited copper is performed after a profiling-piercing electroerosion treatment. The deposited copper is treated with steel, duralumin, and copper electrode tools at different pulse energies. The treatment with the duralumin electrode produces on the treated surface a web-like structure and cubic-morphology polyhedral dimples about 10 μm in size. The main components of the surface treated with the steel electrode are developed polyhedral dimples with a size of 10 - 50 μm. After the treatment with the copper electrode the main components of the treated surface are large polyhedral dimples about 30 - 80 μm in size. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental studies of the crack propagation velocity and the dynamic fracture toughness of St. 45 steel and D16T Duralumin using a modified Kolsky method with a split Hopkinson bar. The results of microfractographic analysis of samples are given, and the fractal dimension is determined. The critical stress intensity factors are calculated using the obtained fractal dimension values [ABSTRACT FROM AUTHOR]

An analytical model of the spectrum of thermally stimulated surface plasmon polaritons (TSSPPs) coming to the edge of a linear conducting sample has been developed. It has been found that the spectrum of such TSSPPs obeys neither the Wien law nor the Stefan–Boltzmann law for thermal radiation. The maximum of this spectrum is shifted to the low-frequency region with respect to the spectrum of the absolutely black body, and the magnitude of the shift is proportional to the sample length. The plasmon nature of the intensity increment of thermal radiation from the edge of a plane face of a duralumin sample has been verified experimentally. It has been shown that the intensity and spectrum of this increment can be controlled both by the sample temperature and by the extension of the face. [ABSTRACT FROM AUTHOR]

Edge waves in a three-dimensional plate are considered as the singularity cases of the obliquely incident and reflection fields of Lamb modes and horizontally polarized shear (SH) modes, solved by mode matching based on a real orthogonal relation or the boundary collocation technique. With that, the dispersion curves of the edge waves in a duralumin plate are evaluated. The leaky edge waves are predicted and the one corresponding to quasi-resonance at free-edge in a plane strain plate are verified together with the pure edge waves. The high-frequency features of the dispersion curves are discussed. [ABSTRACT FROM AUTHOR]

The results of X-ray structural, electron-microscopic, and X-ray spectral microprobe studies of Al-based metal solid solutions that underwent nuclear disintegration and that were discovered in nature for the first time are presented. Based on the similarity to technical counterparts, it is suggested to recognize the previously unknown alloys as natural duralumin. [ABSTRACT FROM AUTHOR]

The influence of hydrogen embrittlement of the aluminum Al-4%Cu-0.2%Mg alloy on the parameters of localized plastic strain is studied. Digital speckle photography is used to visualize the localized strain patterns in the D1 alloy. The velocity of localized deformation bands as a function of the yield strength for nonhydrogenated and hydrogenated samples is found. [ABSTRACT FROM AUTHOR]

In the microsize regime, all crystalline metals studied to-date exhibit a “smaller-is-stronger” size effect. Here, we report an unusual weakest-size phenomenon in the precipitated alloy duralumin 2025, i.e., below a critical size of ∼7 μm, the strength increases as the size decreases, while above this size, the strength increases toward the bulk value with increasing size. At the critical size, strain-hardening is also slowest and the room-temperature creep is fastest. Interestingly, the reduction of strength at the weakest size is more significant for the peak-aged state of duralumin 2025 than its naturally aged state. Theoretical modeling shows that at the weakest size, both strengthening mechanisms of precipitation hardening and dislocation starvation are ineffective. The present results indicate that the conventional wisdom of precipitation hardening is not applicable in the micro-regime, and the common “smaller-is-stronger” understanding is incorrect when material microstructures impose internal length scales that can affect strength. [ABSTRACT FROM PUBLISHER]

This paper deals with the processes occurring on the surfaces of materials during the interaction between metal and non-metal parts of various biomechatronic devices, such as prostheses, orthoses and exoskeletons. These mechatronic systems require careful selection of materials for design and manufacturing of their parts taking into consideration not only mechanical properties of the materials, but also their tribological characteristics. Friction pairs duralumin - fluoropolymer and stainless steel 100CrMn6 - fluoropolymer were chosen for the research as the samples. Experimental research was carried out with the use of the universal friction machine MTU-1. For this research, the scheme "plate-onplate" was used without lubricants. Friction torque, friction coefficient and the temperature in the contact area versus the runtime were obtained as a result of the experiments. Furthermore, estimation of wear of contacting samples was performed. Analysis of the results allowed us to choose suitable materials for design and manufacturing of orthoses, prostheses and exoskeletons. [ABSTRACT FROM AUTHOR]

A method of determining the aerodynamic-drag coefficient of flat vibrating plates from the vibrogram of free damping vibrations of cantilever-fixed duralumin samples has been developed. From the results of our experiments, simple approximating formulas determining the decrement of damping vibrations and the aerodynamic-drag coefficient through the dimensionless vibration amplitude and the Stokes parameter are proposed. The approach developed in this study for determining the aerodynamic-drag coefficient of a vibrating plate can be a useful alternative to purely hydrodynamic methods of finding the drag of vibrating solids. [ABSTRACT FROM AUTHOR]

The flexural vibrations of D16AT Duralumin specimens have been investigated, showing that the dynamic elastic modulus of D16AT Duralumin is significantly dependent on frequency. It has been found that the dynamic elastic modulus significantly reduces in the frequency range 0-20 Hz, and at high frequencies, it is practically constant. A general method has been developed to determine the modes and frequency of free vibrations of a structure taking into account the dependence of the dynamic elastic modulus of the material on its deformation frequency. Numerical experiments on impulsive loading of an elongated plate have been performed, showing that the frequency dependence of the dynamic elastic modulus of Duralumin should be taken into account in structural analysis. [ABSTRACT FROM AUTHOR]

This article presents the metallurgic study of sixty years old structural hardening Al-Cu-Mg alloys recovered from a double-deck aircraft Breguet 765. This study aims to characterize and understand the evolution of alloys over very long periods thanks to an approach coupling materials characterization and archives researches. The focus is made on two ancient age hardening Al-Cu alloys: A-U4G and A-U4G1, whose compositions are close to the international designations 2017A and 2024 respectively. Multi-scale structural investigation was carry out and mechanical properties were extracted. It is shown that despite natural aging during long periods, these alloys exhibit mechanical properties (yield strength, ultimate tensile strength and rupture strain) close to the expected original specifications. [ABSTRACT FROM AUTHOR]

Titanium and duralumin inserts were introduced into a weld to imitate welding flaws in St3 steel samples. Analysis of the accuracy of locating the introduced flaws with different clustering methods (by digitized shape, main informative parameters, the rise rate of leading-edge envelope) has shown that these methods involve considerable time expenditures. The developed dynamic clustering has been combined with the clustering by main informative parameters and allowed in situ location of flaws during welding, while the weld has not been completed yet. [ABSTRACT FROM AUTHOR]

The fatigue life of ductile metals is controlled mainly by the propagation life of a short surface crack; to clarify the growth behavior of short cracks is crucial factor to the safe design of smooth surface members. However, little has been reported on the growth behavior of short surface cracks in thermal-chemical treated duralumin. In the present study, stress-controlled fatigue tests (under rotating bending load) for 70 hours artificial aged duralumin 7075-T6 without chemical treatment case (1) and with chemical treatment case (2). The growth behavior of short cracks was monitored by a plastic replication technique and the surface damage (short crack propagation) during cyclic stressing was observed by optical microscopy. The physical background of fatigue damage for case (1) and case (2) was discussed from the viewpoints of the initiation and growth behavior of short cracks.

Based on the experimental data on the roughness parameter Ra, which stands for the mean arithmetic deviation of the profile, as obtained in the process of turning test specimens from different materials with constant elements of the cutting mode (depth a and velocity v) and structural-geometric parameters of the cutting tool, but with different feed rates f, the probability-statistical method for estimating the influence of feed rate f on the resulting surface roughness by the parameter Ra is proposed using the theory of a small sample.

The purpose of this study is to examine the effect of peening on the fatigue life of a duralumin plate containing a hole with rounded edges. To this end, duralumin plates containing holes with rounded edges with a radius of 0.5 mm were treated by cavitation peening (CP) and shot peening (SP). Fatigue tests under uniaxial tensile loading were carried out to obtain the lifetime versus applied stress curves, i.e., the S - N curves. Then, the fractured surfaces were examined using SEM. Also, a combination of residual stress measurements with electro-chemical polishing was carried out to evaluate the compressive residual stress profile with respect to the depth into the wall surrounding the hole. The results showed that the lifetime of the CP specimen was almost 25 times larger than that of the as-machined one. The fatigue strength, also, was increased by 18% by cavitation peening. In contrast, shot peening reduced the lifetime, since this caused the formation of a roll over layer at the rounded edges, from which cracks due to high stress can initiate. The effect on the fatigue strength of a plate with a hole can be explained on the basis of whether or not roll over occurs and on the residual stress profile with respect to the depth from the surface surrounding the hole. [ABSTRACT FROM AUTHOR]

The paper presents a type of recoilless disruptor developed according to the studies of two disruptors performance and shortcomings currently used DR2 and RICHMOND, respectively. In creating the new disruptor, there were kept some common elements of the two disruptors taken as models of operation (ex. dimensions from RICHMOND were used to design the new system of disruption). [ABSTRACT FROM AUTHOR]

The paper studies the interaction of Lamb waves with the free edge of a plate. The reflection coefficients of a Lamb mode at a plate free edge are calculated using a semi-analytical method, as a function of frequency and angle of incidence. The conversion between forward and backward Lamb modes is thoroughly investigated. It is shown that at the zero-group velocity (ZGV) frequency, the forward S1 Lamb mode fully converts into the backward S2b Lamb mode at normal incidence. Besides, this conversion is very efficient over most of the angular spectrum and remains dominant at frequencies just above the ZGV-point. This effect is observed experimentally on a Duralumin plate. First, the S1 Lamb mode is selectively generated using a transducer array, second the S2b mode is excited using a single circular transducer. The normal displacement field is probed with an interferometer. The free edge is shown to retro-focus the incident wave at different depths depending on the wave number mismatch between the forward and backward propagating modes. In the vicinity of the ZGV-point, wave numbers coincide and the wave is retro-reflected on the source. In this frequency range, the free edge acts as a perfect phase conjugating mirror. [ABSTRACT FROM AUTHOR]

Boiling crisis and evaporation of droplets of ethanol water solution on a horizontal ceramic heating surface were studied experimentally. The experiment was performed on duralumin substrate with SiO 2 . The coating was obtained by nanoparticles plasma spraying. Measurements of the contact angle of the aqueous solution onto the ceramic surface were performed. Most evaporation relates to an increase in the area of the wetting droplet surface and only 10–20% of evaporation relates to the effect of diffusion and change in the thermal–physical coefficients. Maximal instability of the bubble microlayer for alcohol solution with C 0 = 20–40 mass% is observed. The critical heat flux behaves non-monotonously at a change in alcohol concentration in solution, and there are two extremes. The maximal value of sustainability coefficient at evaporation of droplets of ethanol solution corresponds to alcohol concentration of 20–30 mass%. Concentration gradient leads to instability of a triple contact line at the bubble bottom and a decrease in the dry spot area; this promotes higher critical heat flux levels (CHF). The behavior of a binary mixture depends not only on the Marangoni effect at the droplet edges, as thought previously, but also on the unsustainable behavior of the bubbles contact line. The heat transfer coefficient of ethanol solution in the spheroidal state decreases with a rise of wall overheating and spheroid diameter. Experimental dependence of the vapor layer height on wall overheating at boiling crisis was derived. The height of this layer (60–80 μm) at Leidenfrost temperature manifold exceeds the surface microroughness value (1–1.5 μm). [ABSTRACT FROM AUTHOR]