STRUCTURE-PROPERTY RELATIONSHIPS IN AL-LI-CU-MG-AG-ZR ALLOY X2095

Although aluminum-lithium alloys showed initial promise for aerospace applications, implementatation has not proceeded swiftly. In this study, efforts were made to design and develop microstructures with good fracture and fatigue crack propagation resistance to achieve a better balance of mechanical properties in the high strength alloy X2095. Lower aging temperatures were employed, resulting in precipitation of shearable delta' (Al3Li) particles and reduced subgrain boundary T1 precipitation. Although fracture toughness was not significantly altered in the 1.6 Li variant, improvements approaching 50% were achieved in the 1.3 Li alloy. Intrinsic fatigue crack propagation resistance was also slightly improved due to reduced environmental interactions. These improvements were made without altering the 660 MPa yield strength.