Grain boundary failure in an Al–Li alloy

AbstractThe tensile properties and fracture characteristics of 8090 alloy (Al–Li–Cu–Mg–Zr) plate have been investigated in the T351 and T651 tempers in the temperature range 77–295 K. In the T651 temper, improved strength and ductility occur as the temperature decreases and the fracture mode is dominated by fracture at high angle grain boundaries. In the unaged temper (T351), the in-plane tensile properties increase as the test temperature decreases and the fracture mode is predominantly double shear linkage of void sheets. In the short transverse direction, the fracture mode changes between 153 and 77 K from ductile to brittle intergranular with a concomitant loss in ductility. An explanation for this behaviour is proposed.MST/675