New Generation Al-Li Alloys with Superior Attributes for Design, Manufacturing and Performance of Next Generation Aerostructures

Al-Li alloys offer opportunities for step-change in aerostructural performance through density reduction, stiffness increase and increase in fatigue crack growth resistance.  However, second generation Al-Li alloy products (e.g., 2090, 8090 and 2190) exhibited significant in-plane and through-thickness anisotropy in mechanical properties, which manifested in undesirable design and manufacturing characteristics such as crack deviation and micro-cracking during cold hole expansion.  In addition, they showed low fracture toughness, poor corrosion resistance and poor thermal stability.  In this presentation, the results of intense R&D are shown which demonstrate the understanding of the underlying metallurgical causes of the undesirable characteristics.  The work has culminated in key alloy design principles which have led to the successful development and commercialization of 3^rd Generation Al-Li alloys with highly desirable and balanced characteristics.  The new Al-Li alloys, in combination with advanced design concepts, offer opportunities for breakthrough structural performance enhancements for next generation aerospace applications