METALLURGICAL ABSTRACTS (GENERAL AND NON-FERROUS) Yolume 3 DEGEMBER 1936 Part 12 I.—PROPERTIES OF METALS (Continued from pp. ‘139-449.) ♦Tensile Properties of Single Crystal and Polyerystalline Aluminium. G. Welter and T. Mojmir (Wiadomości Instytutu Metalurgji i Metaloznawstwa (Warszawa), 1936, 3, (3), 130-136).—[In Polish, with German summary.] In the preparation of large single crystals of aluminium from the polyerystalline metal by recrystallization the orientation and shape of the single crystals depend on the purity of the metal, e.g. with 99-8% aluminium tho crystal boundaries are always perpendicular to the axis of the rod, whereas with 99-5% metal the crystal boundaries are practieally always parallel to this axis. With rods consisting of two large crystals the relative elongation at the grain boundary is the smallest. The naturę of the fracture of the specimen and the reduction in area depend on tho crystal structure. Determinations of the elastic limits (0-001,0-002,0-01, and 0-2% permanent deformation) show that there is a sudden transition from purely elastic to plastic deformation so that the load-elongation curve bends sharply at right angles. The highest elastic modulus was obtained with single crystal 99-8% aluminium (7150 kg./ mm.3), while the average valuo for polyerystalline aluminium is 6500 kg./mm.2. The elastic limit (0-001% elongation) yaries from 0-75 to 1-6 kg./mm.2; the tensile strength of single crystal aluminium is 4-5 kg./mm.2 and the elongation 50-100%. With inereasing grain-size the tensile strength of aluminium decreases rapidly at first, then more slowly—A. R. P. ♦Contraction of Aluminium and Its Alloys During Solidification—n. (Losana.) See p. 503. ♦Temperature Coefflcient of Electrical Resistance of Aluminium. Maurice Henri (Congres Internat. Mines M it. Geol., Section de MŁtallurgie, 1936, 2, 165-166; and lim . M it., 1936, 33, (7), 420-421).—[In Freneh.] The resistiyi- ties at 20° C., p20, of aluminium 99-996, 99-56, 99-12, and 98-63% pure were determined as 2-620, 2-767, 2-780, and 2-835 microhms/cm., respectiyely. The corresponding yalues for the temperature coeff. of resistance, (3„0, measured between 20° and 70° C., are 0-00433, 0-00400, 0-00413, and 0:00400; all ± 0-00008. The product p20p2o i® constant within the limits of esperimental error, a result in agreement with Mathiessen’s law.—J. C. C. *K Spectrum and Conductibility Electrons of Solid and Liąuid Aluminium. Jules Farineau (Compt. retid., 1936, 203, (11), 540-541).—The work of Siegbahn and Karlsson (Z. Physik, 1934, 88, 71) and K unzl (Z. Physik, 1936, 99, 481) has been extended to embrace both liąuid and solid aluminium, and a special study of the [3 bands, which gives information of the electrons of conductibility. —J . H . W. ♦Investigation of Gases in Aluminium by the Complex Method. I. F. Kolobney (Zvetnye Metalli (Non-Ferrous Metals), 1936, (5), 110-120; (6), 115-124).—[In Russian.] By means of a specially constructed yacuum furnace the gas content of aluminium was determined, separato yalues being obtained for the free and combined gases. Nitrogen is almost insoluble in aluminium, but at high temperatures forms nitrides. Carbon dioxide behaves similarly. Most of the gas found in aluminium, irrespective of the method of manufacture, is hydrogen (up to 70%); the remainder consists of methane ♦ Denotes a paper describing the results of original research. t Denotes a first-class critical reviow. LL 488 Metallurgical Abstracts Y o l . 3 (up to 20%), carbon monoxide, and nitrogen. Ingots cast in an argon atmospbcrc havc tbe maximum and those cast in steam tho minimum density. Castings made at 870° C. have a density about 8-9% below that of those made at 670° C. Aluminium melted in vacuo absorbs Silicon from porcelain and fireclay crucibles, up to 0-8% being absorbed in 1 hr. Specimens cast in water vapour have an exceptionally fine-grained structure.—N. A. *The Structure o£ Aluminium, Chromium, and Copper Films Evaporated on Glass. R. Beeching (Phil. Mag., 1936, [vii], 22, (150), 938-950).—Eyaporated films of aluminium, chromium, and copper on glass when examined by electron diffraction have been shown, when very thin, to eonsist mainly of oxide. In tho case of aluminium the oxide is related to y-Al20 3. The effect of varying the conditions of evaporation were studied. Tho inyestigation includes a study of tbicker films actually containing metal, the effccts of low-temperature heating, and the mechanical properties.—W. D. J. *0n the Figuring and Correcting of Mirrors by Controlled Deposition of Aluminium. John Strong and E. Gaviola (J. Opt. Soc. Amer., 1936, 26, (4), 153-162).—The known method of deposition of metals eyaporated in yacuum is controlled by using a scrcen or mask and rotating tho mirror electro- magneticaUy. The details of methods for changing the form of mirrors (c.g. spherical to parabolic) by this means are described.—R. G. *Aluminizing of Large Telescope Mirrors. J. Strong (Astrophys. ■/., 1936, 83, 401-123).—A history of the evaporation process is given, including the contributions of Ritschl and others, and the present techniąuc is described in detail. Formulaj are developed which give the thickness of the film produced by a cireuiar array of evaporation sources. Applications for the cases of 40 in. and the 108 in. tanks are discussed. Reference is made to the application of non-uniform films in tho figuring of mirrors. Methods of cleaning the mirrors preparatory to coating are discussed. Tho techniąue of obtaining high yacuum in large tanks is treated. The reflectivities and other properties are given for eyaporated films of aluminium and silyer, as well as chromium, platinum, palladium, rhodium, tin, gold, and copper. Observa- tions on aluminized astronomical mirrors in use for oyer 3 years are described. The results of a study of the oxidation (corrosion) of aluminium by means of measurements on transmissivity and reflectiyity of partial films is reported. The different seta of eąuipment that havo been developed in incrcasing size up to the 108-in. tank are described. The history of the application of the process to astronomical mirrors is given.—S. G. *Studies on the CWdation of Metals. IV.—The Oxide Film on Aluminium. G. D. Preston and L. L. Bircumshaw (Phil. Mag., 1936, [yii], 22, (148), 654- 665).—The oxide film on aluminium at room temperature was isolated by remoying the metal by treatment in dry HC1 gas at 250° C. Electron diffrac­ tion photographs of the film show that it is amorphous. Heating tho film at temperatures up to 650° C. does not induco crystallization, but at 680° C. crystallization begins slowly. The film becomes a random mass of smali crystals of cubic y-Al2Os, tho form of alumina which is present on the surface of molten aluminium.—W. D. J. *Altemating Current Investigations on Anodically Oxidized Aluminium. Werner Baumann (Z. Physilc, 1936, 103, (1/2), 59-66).—The diclectrie properties of aluminium oxide films formed anodically are related to the yoltage and freąuency of the a.c. used for their measurement, and to tem­ perature and humidity.—B. C. ♦Different Behaviour of Single Crystals Grown from the Molten Metal and Obtained by Recrystallization using Aluminium of Varying Purity. F. Gisen (Light Metals Research, 1936, 4, (22), 379-381).—Translated from Z. Metall- kunde, 1935, 27, 256; see M et. Abs., this yol., p. 29.—J. C. C. 1936 I.—Properties of Metals 489 Study o£ the Manufacture, Properties, and Uses of Refined Aluminium. 11. Gadcau (Chim. ct Ind,., 1935, 34, (5), 1021-1026; also Metallwirtschaft, 1930, 15, (30), 702-705; and (summarics) Metallurgist (Suppt. to Engineer), 1935, 10, (Dcc. 27), 94-90; Light Metals Research, 1930, 4, (14), 220-224; and Aluminium and Non-Ferrous Rev., 1930, 1, (11), 499-501, (12), 535-530).— Read at the Congres International des Mines, dc la Mćtallurgie, et de la Gćologie appliąuće. Sec M et. Abs., this vol., pp. 09, 237.—W. A. C. N. ♦Recrystallization Diagram of Antimony. J. Czochralski and E. Przyjemski (Wiadomości Instytutu Metalurgii i Metaloznawstwa (Warszawa), 1930, 3, (3), 113-115).—[In Polish, with German summary.] Cylinders of commercial antimony were cast inside copper rings 15 mm. high and 13 mm. internal diameter, the whole compressed to 1,5,10,25,50, and 70% reduction in lieight, and the grain-size measured after annealing for 30 minutes at 300°-610° C. Maximum grain-size was obtained after 1% reduction at all annealing tem­ peratures ; with inereasing degree of reduction the grain-size decreases rapidly, being only about one-tenth of tho maximum after 70% reduction. After annealing at 010° C. metal rcduccd 1% showed grains about 8 times the size of those obtained by annealing at 300°-400° C., and about 10 times the size of those in metal reduced 50%.—A. R. P. ♦The Magnetic Properties of Antimony. D. Shoenberg and SI. Zaki Uddin (Proc. Cambridge Phil. Soc., 1936, 32, (3), 499-502).—The magnetic suscepti- bility of antimony both parallel and perpendicular to tho trigonal axis is independent of field down to 4° K. The numerical value of the susceptibility parallel to the trigonal axis decreases with inereasing temperature, similarly to that of bismuth, but perpendicular to the trigonal axis there is no tempera­ ture dependence. A comparison of the results at higher temperatures with earlier meąsurements, suggests that the susceptibility of antimony, like that of bismuth, is very sensitivo to addition of foreign elements.—S. G. ♦Photoelectric Properties of Barium and Calcium. N. C. Jam ison and R. J. Cashman (Phys. Rev., 1930, [ii], 50, (7), 024-631).—Using a photo­ electric celi in which the barium was fractionated, and repeatedly distilled, the work-function of barium at room temperature was determined as 2-520 and 2-510 e.v., at the beginning and end of the experiments.