INFLUENCE OF MICROSTRUCTURAL FEATURES ON THE FRACTURE-RESISTANCE OF ALUMINUM-LITHIUM ALLOY SHEETS

The effects of various microstructural features on the plane-stress fr acture resistance (K-R) of ternary (Al-Li 2090) and quaternary (Al-Li 8090) aluminium-lithium alloys are illustrated, discussed and summariz ed. These microstructural features include (i) the nature of intragran ular precipitates (which control the texture governed planar deformati on), (ii) the presence of grain boundary precipitates and (iii) presen ce of coprecipitates. Suitable modifications in the alloy chemistry, p rocessing and thermo-mechanical treatments, that would enhance the pla ne-stress fracture resistance of these alloys are suggested based on t hese observations.