High Strength Light Alloys: A Note on Certain Problems Arising from the Adoption of New Alloys

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.