THE METALLURGICAL ASPECTS OF ALUMINIUM-LITHIUM ALLOYS IN VARIOUS PRODUCT FORMS FOR HELICOPTER STRUCTURAL APPLICATIONS

Abstract
The reduced density and concommitant increased elastic modulus of aluminium-lithium based alloys have created intense interest throughout the aerospace industry and associated organisations since the beginning of the present decade. Many Companies and Establishments have evaluated the new alloys to have emerged with a view to potential incorporation into their specific products and this paper describes the results from a number of such metallurgical examinations undertaken at WESTLAND HELICOPTERS during the past four years. This paper reports on some of the studies of wrought product forms in alloys 8090, 8091 and 9052XL. Microstructural investigations and mechanical property data such as tensile, compression, fatigue and fracture toughness are presented and have generally shown these new materials to exhibit properties which match those of currently used non-lithium containing aluminium alloys ; the results of some of these parallel and comparative studies are included in the paper. Finally, mention is made of aspects of which aluminium-lithium alloys show some deficiencies and any problems anticipated in their future use will be briefly discussed.