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LONDON. Institute of Metals (Autumn Meeting, Glasgow), September 2.—J. H. Andrew and Robert Hay: Colloidal separations in alloys. The β constituent may break down into colloidal a and colloidal γ, and upon submitting these to an electrical current, the colloid is destroyed and the crystalline phase begins to make its appearance. The ageing of duralumin may be due to the deposition of the magnesium compound in the colloidal form, when the increase in hardness would be due rather to the fineness of state of division of the separating phase than to its specific properties.—John S. Brown: The influence of the time factor on tensile tests conducted at elevated temperatures. With non-ferrous alloys there is a critical temperature condition, above which the rate of application of the load has an important influence on the observed strength. This time factor tends to lose its effect when the rate of loading is kept below 1 ton per sq. in. per day, and this value is consequently put forward as of basic importance in such investigations.—R. B. Deeley: Zinc-cadmium alloys. A note on their shear strengths as solders. A substitute for brazing spelter was required for the motor-cycle industry. The working temperature of the substitute solder had to be below that likely to promote coarse crystallisation of the hard-drawn steel tubing of the frame, and the melting point had to be sufficiently above the enamel stoving temperature (about 180° C.) for joints made with the alloy not to fail during enamelling. Zinc-cadmium alloys in pure shear show the strongest alloy to be near the eutectic composition. This alloy is considerably stronger than tinman's solder, 8 tons/sq. in. compared with 4 tons/sq. in.—J. W. Donaldson: Thermal conductivities of industrial non-ferrous alloys. The thermal conductivities of 70: 30 brass, high tensile brass or manganese bronze, Admiralty gunmetal, ordinary gunmetal, bearing phosphor bronze, white bearing metal, and monel metal are low, ranging from 0.067 f°r monel metal to 0.242 for 70: 30 brass. Increasing the temperature increases the conductivities. The alloys of tin and copper have a lower conductivity than those of zinc and copper, while nickel lowers considerably the conductivity of an alloy containing it.—Marie L. V. Gayler: On the constitution of zinc-copper alloys containing 45 to 65 per cent, of copper. In an equilibrium diagram, no change in microstructure of alloys, consisting wholly of the β constituent could be detected.;—J. L. Haughton and W. T. Griffiths: The β transformations in copper-zinc alloys. The change of resistivity with temperature was determined for some alloys containing from 46 to 63 per cent, copper. Above 55 per cent, copper the β-transformation temperature is 453° C.; between 55 per cent, and 51 per cent, copper it takes place at temperatures rising from1 453° C. to 470° C.; with less than 51 per cent, copper the transformation temperature is 470° C. These data are opposed to the theory that this is a eutectoid transformation. The specific resistances at room temperatures were also measured: after annealing just above the transformation point. The resistance falls rapidly as the copper decreases from 61 per cent, to 53.5 per cent., and less rapidly to about the 50 per cent, copper alloy; it rises steeply from this point with further decrease of copper content. Thus the two boundaries of the field at room temperature occur at 50.0 and 53.5 per cent, of copper.—C. H. M. Jenkins: The physical properties of the copper-cadmium alloys rich in cadmium. Alloys containing up to 5 per cent, of copper in the cast, rolled and annealed states, were used. The effect of even a small addition of copper to cadmium is to cause the formation of a second constituent CuCd3; this increases the tensile strength and Brinell hardness and prevents the grain growth of cadmium on annealing. Additions of more than 3 per cent, of copper do not materially improve the mechanical properties of cadmium owing to the presence of too large a proportion of the brittle compound.
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Societies and Academies. Nature 116, 378–380 (1925). https://doi.org/10.1038/116378b0
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DOI: https://doi.org/10.1038/116378b0