Range Of Aluminium Alloys Research Articles

Вплив швидкості охолодження при кристалізації на структуру сплавів В95 та Д16

It is known that the alloys of the Al-Zn-Mg-Cu and Al-Mg-Cu systems have a very wide crystallization interval (over 100°C) and therefore the technology of roll pouring-rolling of sheet blanks from such alloys has not yet been developed. In this regard, the development of scientific and technological foundations of roll casting for such a range of aluminum alloys is an important scientific and practical task. The purpose of this work is to determine the possibility of aluminum alloys B95 and D16 (crystallization intervals are 160°C and 132°C, respectively) for casting-rolling based on the analysis of the effect of cooling intensity on their structure and mechanical properties. The research was carried out on full-scale samples of B95 and D16 alloys by comparing the obtained experimental values. Determination of the temperature parameters of phase transformations in the studied alloys was carried out using the Derivatograph Q-1500-D device. As a result of the tests, the curves of the differential thermal analysis and the fraction of the liquid phase depending on the temperature were obtained. Based on the results of the research, the suitability of B95 and D16 aluminum alloys for casting and rolling has been substantiated. It was found that the size of α-phase grains for B95 and D16 alloys as the cooling rate increases decreases to 120...200 μm (for cooling rates of 2.5...8.8°С/s), and to 40...70 μm (for cooling rates cooling ~1000°С/s). It has been proven that the hardness of B95 and D16 aluminum alloys mainly depends on the α-phase, therefore, when developing roll casting modes, it is advisable to take into account the hardening features of this structural component (α-phase). At the same time, it should be noted that at the intensity of heat removal, which is typical for roll crystallizers, the obtained sheet blanks from the studied alloys will have dispersed crystal structures with a uniform distribution of phase components along their cross sections. A natural consequence of such primary crystalline structures of cast blanks will be a guaranteed high level of strength characteristics of sheet metal rolled from them. Keywords: cooling rate, alloy, crystallization, structure, phase composition, metal rolling

A scaling law for predicting the ballistic limit of aluminium alloy targets perforated in ductile hole formation

The ballistic performance of monolithic targets perforated in ductile formation by rigid projectiles can be reasonably approximated by an energy balance based on the work done in expanding a hole from zero initial radius to that of the penetrating projectile. For a specific projectile, these energy balance laws can be expressed in terms of a simple scaling law which requires an empirical fit to ballistic data. However, once this fit has been performed for a specific projectile against a specific target material, predicting the performance of other materials against this projectile can be done from a simple quasi-static compression stress–strain curve, provided the target is perforated in ductile hole formation. Four variations of ductile hole formation analytical and semi-empirical models have been reformulated as scaling laws and evaluated for their ability to characterise the performance of monolithic aluminium plates impacted by 7.62 mm APM2 projectiles at normal incidence. The database used to fit and evaluate the performance of the scaling laws incorporates more than 1600 V50 measurements against 24 different alloys and tempering/strain-hardening combinations with thicknesses ranging from 16.2 to 63.5 mm. The highest performing scaling law formulation was found to characterize the measured V50 to within 5% of the experimental value for over 97% of the database entries. Further improvements in accuracy are likely impossible when representative stress–strain curves are used for performance characterization rather than tests of each individual plate used in the ballistic tests. The scaling law can be applied to predict the performance of targets perforated in ductile hole formation with a high level of confidence, an example of which is provided for the 12.7 mm APM2 projectile against a range of aluminium alloys.

Theoretical and Experimental Study of the Al – Cu – Si – Sn Phase Diagram in the Range of Aluminum Alloys

Phase compositions of aluminum alloys of the Al – Cu – Si – Sn system are studied by computational and experimental methods. The computations are performed with the use of the Thermo-Calc software; the experimental part is implemented with the use of light and scanning electron microscopy, microscopic x-ray spectrum and thermal analyses. According to the computation, the quaternary system may exhibit layering of liquid and occurrence of monotectic transformations including a five-phase nonvariant one. The solidus temperature of the quaternary alloys depends little on the presence of copper and silicon and virtually coincides with the melting temperature of pure tin. The solubility of tin in the aluminum solid solution and in the (Si) and Al2Cu phases is negligibly low. Heating at 500°C changes substantially the morphology of the tin phase.

Pulsed plasma electrolytic oxidation processes for aeronautical applications and their technical application

A range of aluminium alloys have been treated by plasma electrolytic oxidation in different alkaline electrolytes containing silicate, aluminate, vanadate and other additives, under pulsed current conditions and the dependence of oxide thickness growth rates on variation in electrolyte and operating conditions measured. The oxide morphology was examined by SEM, and coating phase and crystal size analysis was carried out by XRD. Coating hardness varied with anodising current type and electrolyte composition, and the incorporation of dispersed nano silica particles.

The Use of High Pressure Direct Squeeze Casting for Semi-Solid Processing of Aluminum Base Nano Composites

The production of nano-reinforced aluminium alloys in volume and quality suitable for subsequent shape casting has been problematic. Large specific surface area and high interfacial energy of the particles combined with high surface tension of the aluminium melt makes it difficult to add appreciable numbers of particles to the melt, even when later de-agglomerated by techniques such as ultrasonic cavitation. The objective of this work was to develop a technique to incorporate particles using pressure applied while the alloy was in a semi-solid state. The composites produced could be used as a master alloy to inoculate large batches of metal for subsequent casting using any suitable technique. The results show excellent distribution of 50 nm alumina particles in 2014 material. The procedure appears to have broad applicability to a full range of aluminium alloys and particle reinforcements.

Corrosion Pit Induced Stresses Prediction from SEM and Finite Element Analysis

Corrosion damage due to pitting is commonly observed in a wide range of aluminum alloys and structural steels that are being used for aerospace and naval structural applications. In order to better understand the particle-induced pitting corrosion in aluminum alloys, experimental measurements were conducted on aluminum 5059 specimens with UTS of 360–370 MPa to observe the corrosion degradation and pits. Both optical microscopy and SEM of various corroded and sensitized specimens were carried out to see how the pits grow and progress with time. An analysis procedure is developed using CAD and finite element software to predict stresses due to corrosion pits. The results obtained indicate that as the duration of the specimen sensitization increased from 29 days to 50 days, the highest stress levels have increased by about 56%. However, further increase in the sensitization time from 50 to 100 days has very little effect on the stress level. It is possible that the deformation due to the exfoliation of the specimen surface layers or the tearing of the surface layers in and around the pits is so severe that the surface stress has decreased due to material failure by developing cracks.

Pretreatment of aluminium for electrodeposition

Aluminium is a very useful material for the production of both cast and extruded fabrications due to its low density and high strength to weight ratio. A wide range of aluminium alloys are available having an equally wide range of mechanical properties. Aluminium fabrications usually require some form of finishing operation to improve the appearance or corrosion resistance. Anodising, chromating, organic finishing and electroplating are commonly carried out. Electroplating of aluminium can be quite difficult to accomplish successfully so it is the aim of this paper to clarify some of the issues and difficulties associated with electroplating of aluminium.

Sliding wear behaviour of aluminium-based metal matrix composites produced by a novel liquid route

TiC-reinforced MMCs have been produced in a range of aluminium alloys using a novel casting technique which results in spontaneous incorporation of the particles into the melt and thus strong bonding between the particles and the matrix. The sliding wear behaviour of the extruded composites has been studied as a function of load and particle volume fraction and has been compared with a commercially available SiC-reinforced composite. In all cases, alloy reinforcement resulted in a reduction in wear rate and an increase in the load at which the transition from low rate wear to high rate wear occurred. In the low rate wear regime, the wear coefficients of all the alloys in both the reinforced and unreinforced states were similar, and since the TiC-reinforced A356 alloy was the hardest (due in part to the grain refining action of TiC), it exhibited the lowest wear rate (lower than that of the SiC-reinforced composite). Wear of the steel counterface depended on the mechanism of wear of the composite. An increase in load generally resulted in an increase in wear rate of both the composite pin and counterface, and the reasons for this are presented. Increasing the volume fraction of particles in a composite reduces its wear rate but generally increases the wear rate of the counterface. It is suggested that when both counterface and composite wear are considered, an optimum volume fraction of particles exists at which wear is lowest.

The performance of aluminium alloys and particulate reinforced aluminium metal matrix composites in erosive-corrosive slurry environments

A range of aluminium alloys and particulate reinforced aluminium metal matrix composites has been tested in an apparatus which simulates the erosive-corrosive action of a slurry. The slurry used in the investigation is composed of synthetic mine water and silica sand. The corrosion component of the mass loss was found to be an important synergistic factor. The addition of ceramic reinforcement particles to the matrix alloys has a detrimental effect on the slurry erosion resistance.

Surface Analysis and Bonding of Aluminium-Magnesium Alloys

Abstract Previous work has used X-ray photoelectron spectroscopy to examine the surface compositions of aluminium-alloy substrates subjected to various surface pretreatments prior to bonding. It was proposed that the presence of magnesium in the oxide structure adversely affected the service-life of adhesive joints when they were exposed to aqueous environments. The present work further explores this correlation by examining a range of aluminium alloys, basically of the same composition except for the level of magnesium in the alloy.

Anodic Oxide Coating Formation on Aluminium Alloys

Results are presented on anodising a range of aluminium alloys under conditions of the D.T.D. Specification 910, with special reference to the following points: weight of coating, attack on the met...

The Quantitative Adhesion of Nickel Electrodeposits to Aluminium Alloys

AbstractThe quantitative adhesion of electrodeposited nickel to a range of aluminium alloys, prepared by etching in a nitric-hydrofluoric acid mixture and subsequently treated in a sodium zincate solution, has been examined. A standard method has been devised which will yield adhesion in excess of the ultimate tensile strength for most alloys; a slight variation is necessary for high magnesium or silicon alloys, on which the adhesion, although high, is slightly less than the tensile strength. A hypothesis on the theory of the process is advanced. An appendix on quantitative adhesion testing is of general application.