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A sensitive spectrophotometric method for the determination of titanium by formation of its complex with tannin and thioglycollic acid at pH 4 has been developed. The intense yellow colour is measured at 400 nm and the system obeys Beer's law over the range 0.2–5 ppm titanium in the solution measured. The method is applicable to titanium-treated steels, stainless steels, permanent magnet alloys and duralumin alloys. The interference of Co, Ni, Cr, Mn, V, Mo and W can be eliminated by prior separation of titanium by controlled addition of cupferron in the presence of thioglycollic acid (TGA). Copper can be quantitatively separated by precipitation with TGA and determined complexometrically with EDTA, with PAN as indicator. Niobium interferes even in traces.

Push-pull cyclic plastic deformation tests were carried out on three batches of Duralumin specimens, which after solution annealing, were subjected to aging at the following temperatures, respectively: room temperature, 200°C and 350°C. The R. T.-aged alloy behaves as a homogeneous alloy, in that the irreversible cyclic strain (eic) analysis of Sleeswyk and others (1978) brings the cyclic σc-eic curve in coincidence with the monotonic stress-strain curve. The two other alloys exhibit behaviour characteristic of a cyclic hardening coefficient which is lower than that obtained in unidirectional testing. The cyclic hardening coefficient for the overaged material is found to be a constant fraction, 1/4 to 1/3, of the unidirectional stress. The alloy aged at 200°C produces the constricted loops characteristic of precipitation-hardened alloy in which the mean free path of the mobile dislocations is determined by the distance between precipitates. The effect is absent in the material aged at 350°C. Plasticity, Fatigue, Dislocation Mobility, Precipitation Hardening.

A differential scanning calorimeter was used for the determination of the thermal conductivities of various solid materials having a wide range of values. The tested materials were teflon, duraluminium and electrolytic copper. This method provides a reliable way to measure λ in the range 0.200–400 W m−1 K−1 for temperatures between 40 and 100 °C.

This report provides test results of composite plates made up of combinations of Duralumin, Armor Plare and Low Carbon steel plate.

Precipitation in duralumin-type Al-Cu-Mg alloys is more complex than that in binary Al-Cu alloys. According to Brommelle and Phillips (1), the principal constituents present in equilibrium in these alloys are: (1) the aluminium-rich solid solution α; (2) the phase Al2CuMg (S phase); and (3) the phase CuAl2 (θ-phase). The relative amounts of S and θ depend upon the copper to magnesium weight ratio in the alloy, the equilibrium ratio being equal to 2.6. If the ratio is less than 2.6 in the alloy, then the phases present in equilibrium will be only the solid solution α and S, on annealing near the solidus temperature.

Three investigations directly related to light armor for aircraft are described in this report: the effect of yaw upon penetration, the effect upon bullets of penetrating very thin Duralumin sheets, and the use of shielding structures in the form of gratings. Data illustrating these topics are still in the process of collection. Methods of these investigations are, however, described and preliminary results of interest are shown. An effect of yaw upon penetration of about 1.4 per cent limit velocity increase per degree yaw was found for samples of 17 ST Duralumin, STS armor plate and hard homogeneous armor. The largest yaw effect was measured using a plate of STS armor hardened to Brinell 370. The smallest measured yaw effect was obtained on a sample of 0.25 inch face-hardened armor. It is shown that apparent differences in plate quality or bullet quality of 50 feet per second in plate testing may be due to several degrees of yaw of the bullets at impact. If armor is spaced back inside the fuselage of an aircraft, bullets may tumble before striking the armor due to penetrating a Duralumin sheet at large obliquity and 23 inches separation on the limit of a typical bullet-proof plate at normal incidence is shown to be more than 200 feet per second. There is a gain in weight efficiency even when the resolved weight of the Duralumin is included with that of the armor plate. The efficiency of a light grating used as the first plate of a divided armor structure depends considerably upon design. Certain design improvements have been ascertained. On account of the very large effectiveness of solid shielding plates, it is still uncertain whether gratings or solid plates are better as first members of a divided armor structure.

Evidence is presented indicating that a convective disturbance occurs during ultracentrifugation of dilute solutions in duralumin centerpieces in weakly alkaline medium above pH 8.6. H2 gas is liberated from a duralumin centerpiece at a pH value as low as pH 9.7, probably due to the oxidation of aluminum by aqueous OH−. Another reaction which consumes OH− is also present which is more rapid than the oxidation reaction and probably is the dissolution of the Al2O3 coating. The nature of the convective disturbance which results is discussed.

The paper presents the results of fatigue tests of cylinder specimens made of duralumin PA6 under alternate block loading for bending and torsion. Each block contains n and n cycles with sinusoidal course. Based on the fatigue curves amplitudes suitable for 105, 3·105 and 106 number of cycles to failure were determined. The loading was applied in alternate two-amplitudes blocks by 104, 3·104 or 105 each one (10% of the fatigue life for the given loading level) until failure of the specimen (fig.1).

In the contribution the results of bonded joints laboratory tests are published. For bonding of test samples five different types of quick-setting adhesives were used. The determination of the tensile lap-shear strength of rigid-to-rigid bonded assemblies according to the standard CSN EN 1465 (66 8510) was the aim of carried out tests. The samples were made from steel and duralumin sheets. Ahead of bonding the surfaces of all samples were blasted using corundum grit and degreased. Bonded joints of different adhesive layer thickness were tested. The layer thickness was secured using two copper wires of the appropriate diameter, which were placed between the bonded surfaces. By the test results evaluation the optimum adhesive layer thicknesses were determined, when the concrete bonded joint strength is the highest.

New materials and production technologies demand improved non-destructive techniques for inspection and defect evaluation, especially when critical safety applications are involved. In this paper two Non-destructive Testing (NDT) applications are presented: the inspection of Friction Spot Welding (FSpW) of AA2024-T351 with and without Alclad™ and a composite material GLAss-REinforced Fibre Metal Laminate (GLARE®) with artificial defects. The two applications were tested by Eddy Currents (EC), using both conventional planar spiral probes and a new EC probe developed by some of the authors, called lOnic probe. Four different FSpW conditions were produced and tested in 2 mm-thick plates of duraluminium with and without Alclad™. Three defects were introduced in GLARE® aiming to compare the reliability of the different NDT approaches. The experimental results show that the lOnic probe is able to identify different levels of FSpW quality regions by a distinctive perturbation on the output signal, whereas conventional probe cannot distinguish the different FSpW conditions. Regarding the GLARE® application, it was found that lOnic probe can detect the deeper defect easier than the conventional EC probe.

軟鋼、鋳鉄におけるX線的應力測定に就ては既に瘻々上発表された通りである。超ヂュラルミンに於ては軟鋼類に比し同一應力に対して歪が大きく出る事を考慮し、軟鋼、鉄鋳に於て可能であったX線的應力測定が超ヂュラルミンに於ても可能であるか否かを吟味せんとした。即ち超ヂュラルミンの試験片に夫ヵ降伏点以下の数段の引張並に圧縮應力を加へ各段階毎にX線を管て應力を測定した。その結果上述の如き如何なる應力状態に於てもその機械的應力値とX線的應力測定値とは実験の誤差範囲内にて極めてよく一致し、旦原子格子は完全彈性体として働く事を確認し以て超ヂュラルミンに於てもそのX線的應力測定値は彈性應力に関する限り十分」信頼しで利用し得る事を確認した。

A temperature (100°K) is found, at which accelerated diffusion of point defects in duraluminium as a result of a preliminary deformation at 77°K is still possible. The annealing at 77–300°K shows some peculiarities, leading to a disproportionate change of the thermal conductivity and the electrical resistivity for different T anneal .

COSMIC ray ionization bursts produced by showers of ten or more particles in a small ionization chamber (volume 1 litre) have been recorded at sea-level in Cambridge and, thanks to the hospitality of Prof. P. M. S. Blackett and Dr. H. J. J. Braddick, under 30 m. of clay in London. The data discussed here, curves A (150 hours) and B (350 hours), are from runs with no lead or other dense shower producing material above the chamber (the wall of the chamber was of duralumin, 1·2 cm. thick, so as to avoid as much as possible showers produced by cascade multiplication in the chamber itself). Curve C (500 hours) is the result of similar observations at sea-level with a large ionization chamber (volume 175 litres, wall-thickness 0·3 em. of steel), most of which were published by one of us1 in 1936, when the method of recording was also described. The curves show the number of showers per hour in which N or more particles intersected the ionization chamber; the number of shower particles N was estimated on the basis of a specific ionization in normal argon of 90 ion pairs per cm.

1. The fatigue strength of alloy 01420 is higher than that of alloy AVT1 in air and, particularly, in a corrosive medium. 2. The 01240T1 alloy has a lower specific weight elasticity modulus, fairly high strength properties under static and cyclic loading, and high corrosion resistance in comparison with alloys of the Avial and duralumin types, and is a very promising material for machine building.

THE adhesion of polyethylene to high energy substrates depends on the oxidation of the polymer. Better adhesion was found1 to copper if it was covered with CuO rather than Cu2O, because the former oxidizes the polyethylene; and the adhesion to Duralumin is increased2 when polyethylene is oxidized with dichromate or permanganate. The high adhesion of polyethylene to steel can be depressed by antioxidant in the polymer3, and the poor adhesion to glass is enhanced by use of a suitable oxidizing agent. We now report circumstances, however, in which the adhesion of polyethylene is dependent not on oxidation but on the hitherto neglected concept of mechanical “keying”.

ϱ and λ of quenched duraluminium are measured simultaneously. A clearly expressed maximum at 500°K is observed on the curves of the T q -dependence of the kinetic coefficients, which is in agreement with the accepted models of the kinetics of the formation of the I and II Guinier-Preston's zone in the alloy.

The maximum of the thermal conductivity at the limit of the linear part of the E (ϵ) curve mainly due to the increase of the lattice component is observed in duraluminium, tensile deformed at 77°K. while the electrical resistivity, measured simultaneously, shows a minimum.

In the work discussed below, an exper imenta l ma te r i a l was produced which may prove of value in the design of shielding against y radiat ion, and in calculat ions of mul t ip le scattering of y photons. The to ta l radia t ion intensity at distances up to g00 m removed from the source (r), and the angular distribution of radiat ion at distances of 150, 250, and 400 m were derived in the course of the Work. Measurements were carried out w i t h t h e source and detector p laced at a height of 1 .5 m above the earth. At some points, the measurements were conducted using a source supported at the top of a slender duralumin mast, 28 m in height.

The German metallurgists were the first to discover how to make the light alloy of aluminium which they called duralumin. I understand it is a mixture of 97 per cent aluminium and 3 per cent copper, but it may have a very small percentage of rarer metals. Whereas aluminium has a yield point of about nine tons per square inch, duralumin has a yield point of twenty-five tons per square inch.Before and during the First World War the German aircraft constructors used duralumin in the construction of Zeppelin rigid airships, aeroplanes and seaplanes and flying boats. Towards the end of the First World War, I began to fear that the Germans would invent all-metal aircraft with highly streamlined forms which would increase the speed of their aircraft and that at very high speed with their bombing aircraft, they would fly at almost house top level, drop a time bomb on our works and be at a safe distance before the explosion occurred.

THE heat‐hardened, so‐called “strong,” aluminium alloys such as Avional and Duralumin, require a special technique in making joints. In the common aircraft steels permanent joints are usually made by welding, but this method is only applicable to hardened aluminium alloys to a limited extent, since the unavoidable heating of the joint may destroy the strength of the material—whether produced by annealing at 500 deg., quenching in cold water, and subsequent ageing at room temperature, or by artificial “ageing” at a temperature of about 150 deg. for several hours. Such loss of strength being usually undesirable, riveting must in the majority of cases be substituted for welding; although in recent practice spot welding has come into use, particularly for thin material up to about 1–5 mm. In that case, the heating is only quite local and of short duration, and the resulting loss of strength inconsiderable.

The mechanism of the protective action of aluminum cladding in corrosion fatigue of grade D16AT duralumin was studied.

In order to investigate the range, in which the law of similarity on Vickers hardness is held, the measurement of Vickers hardness of carbon steel and duralumin was taken place under the light loads of 50∼1000g, with attention to the errors due to the work-hardning of test surfaces and the inertia effect of moving parts of the machine. It was acertained that the law of similarity was still held under the 50g load, and that the best method for finishing the test specimens was polishing by electrolysis and the next method by cloth while pouring the cooling material as ether or acetone.

PLANE stress yielding was induced in a duralumin plate by expanding a 12-segmented cylindrical collet. The tangential strains in the plate were measured at ten values of radius by means of single-filament Minalpha resistance wire strain gauges1. At all loads the measured strains in the unyielded portion of the plate fitted the theoretical solution exactly. The measured values in the yielded zone from the inner radius out to the yield boundary are shown for a typical loading in the figure.

Experimental results are reported for the ricochet of steel and duralumin spheres ( 3 8 in. and 1 in. dia.), from shallow depths of water and dry sand. The critical angle for ricochet off water is shown to increase with speed to approach the theoretical limit of 18 √σ deg . For ricochet off sand the critical angle decreases with speed but a cut-off angle exists, 82 √σ deg , for which no ricochet occurs at any speed.

An improved needle point frame for exact line transects in dense herbaceous vegetation was developed (Fig. 1). The apparatus consists of a rigid duralumin bar (B) of about 2.40 m long, with rectangular section (10 cm x 1.8 cm) bounded, at both ends, by a tightening nut system (S). After pushing into the soil two supportstakes (PS), the bar is fixed horizontally at the desired height, by the tightening nut system and with the help of a nivel, in such a way that the point of the needle (A), at its highest position, should be just above the “roof” of the vegetation. The upper part of the bar (B) is a ball-race and shows 80 small alveoles (a) spaced 2.5 cm center to center. The diameter of these alveoles corresponds to the diameter of a small ball linked to a sliding system (SC) surrounding the bar. This sliding system includes mainly two holes (0, and 0,); which command the vertical position of a needle-holder (PA), a handle (b), a ball (u) held by a flexible rod (f) and a rubber-covered metallic cylinder (CM). This produces a sliding friction between the system (SC) and the bar, whose corresponding part is covered with a strip of emery-cloth. This hole allo,ws the rapid, easy and regular movement of the needle.

IN the Boeing factory today stack after stack of shiny duralumin and stainless‐steel ‘cookies’ are being sliced out of raw stock in the same way that cooks used to slice them out of dough.

THE necessity for the development of high strength structural alloys was accentuated by the rapid development of the jet engine, a power unit which brought the speed of flight to within reach of the speed of sound. This major step in engine potentiality put a new urgency on the need for high strength structural alloys to be placed at the disposal of the designer. This deficiency was diminished to a large extent by the production of the aluminium‐zinc‐magnesium‐copper alloys. Once the potentialities were realized of this type of alloy having tensile strengths equal to the low carbon steels and a strength/weight ratio substantially superior to the aluminium‐copper alloys, it found widespread application for primary aircraft structures. The approximate chemical composition of the (Al‐Zn‐Mg‐Cu) alloys is given in table i and compared with that of the Al‐Cu or duralumin type alloys.

The values of the sparking voltage in hydrogen, near the Paschen minimum, were found to be higher at 85° K than at 298° K. With Duralumin electrodes, the difference of the minimum sparking voltage is about 10%.

Single, hemispherical spark cavities were created in water at the pressure end of a Duralumin pressure bar. At the collapse of such a cavity, a transient stress pulse (∼20 μsec duration) is propagated along the bar which is detected by an X‐cut circular disk of quartz of the same diameter as the pressure bar. The charge liberated at the surface of the crystal when the X‐cut quartz disk is traversed by the stress pulse was converted into a voltage pulse which subsequently was amplified and recorded photographically from a cathode ray oscillograph. These photographic records yield only information regarding the total lifetime of the cavity and the maximum amplitude and time variation of the force developed during its collapse. However, an ultra‐high speed photographic technique employed in conjunction with the piezoelectric pressure bar permits an estimate of the peak pressure developed at the site of collapse of the cavity to be made together with an observation of the time variation of the pressure within...