From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Patent specification for a process to improve magnesium base alloys by adding zirconium.
| Identifier | ExFiles\Box 147\2\ scan0072 | |
| Date | 15th February 1938 | |
| 2 511,291 the molten alloy, losses by burning are reduced to a minimum and when no flux is used, salt inclusions in the metal, and therefore their attendant risks of corrosion, are impossible. A further advantage arising out of the invention is that when subjecting the alloys to heat treatment, the duration of the latter is the same as that for the same alloy, containing neither beryllium nor zirconium. In addition the parts subjected to the heat treatment do not become oxidised and retain their original lustre. By way of example, a magesium alloy has been prepared with the analysis:- Al = 6% Zn = 3% Mn = 0.3% This alloy, without addition, has given in the case of sand-cast test-pieces, not heat-treated:- R = 17.7 kgs. per sq. mm. A = 4% the same alloy, with addition of beryllium within the range specified herein, for example of 0.025% of beryllium, has given:- R = 15.4 kgs. per sq. mm. A = 2.9% to this last alloy, there has been added 0.035% of zirconium and there has been obtained:- R = 17.6 kgs. per sq. mm. A = 3.5% In these equations, A and R designate respectively the elongation and tensile stress of the alloy at the breaking point. Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:— 1. A process for imparting to magne- sium base alloys containing beryllium, in which the presence of beryllium causes the formation of a grain, on solidification, which is coarse as compared with the grain of similar alloys in which beryllium is absent, a finer grain structure and correspondingly improved mechanical strength properties, which process comprises adding zirconium to such alloys when molten. 2. Magnesium base alloys containing beryllium, preferably in an amount lying between 0.005 and 0.5%, such alloys having, by virtue of a treatment with zirconium of such alloys in the molten state, a refined grain and improved mechanical strength properties as compared with similar alloys in the preparation or re-melting of which zirconium has not been used. 3. A magnesium base alloy containing 6% of aluminium, 3% of zinc, and 0.3% of manganese and also beryllium in an amount lying between 0.005 and 0.5%, such alloy having, by virtue of a treatment with zirconium of such alloy in the molten state, a refined grain and improved mechanical strength properties as compared with similar alloys, in the preparation of re-melting of which zirconium has not been used. 4. The process for imparting to magnesium base alloys containing beryllium a fine grain structure and improved mechanical strength properties substantially as described. 5. Magnesium base alloys whenever treated by the process claimed in claim 4. Dated this 15th day of February, 1938. ALBERT L. MOND & THIEMANN, 14 to 18, Holborn, London, E.C.1, Agents for the Applicants. Leamington Spa: Printed for His Majesty's Stationery Office, by the Courier Press.—1939. | ||