Study of the tensile fracture process of Al-Li alloys

The fracture mechanisms of 2090+Ce aluminum-lithium alloys aged for different time are studied by means of semi-quantity method, and the process of the tensile fracture crack forming is discussed especially. Statistical and analytical results show that the main fracture features are toughness-hollow, short-transverse delamination and intersubgranular. The toughness-hollow and the short-transverse delamination decrease, and the intersubgranular increase with prolonging of the aging time. There is a close relationship between the aging time and the short-transverse delamination. The conditions of the grain boundary and stress determine the process of the delamination crack forming. The crack is formed first at the center of the specimen, and then at the quarter, the eighth... At last, the whole specimen is divided into serial of parallel segments. In over-aged condition, the short-transverse delamination is restrained by weakening of the intersubgranular. The strength, especially the ductility, is decreased with the fracture model translating from short-transverse delamination into intersubgranular.