Mechanism of embrittlement of al alloy by liquid metal (GA)

The liquid metal-induced embrittlement (LME) of 7075 Al alloy by Ga was inv estigated by using modified wedge open loaded (WOL) specimens. The results showed that the adsorption of Ga atoms could facilitate local plastic defor mation of the base metal and there was an observable concave plastic zone a t the notch tip. A microcrack then initiated when the plastic deformation r eached a critical condition. The threshold stress intensity of LME under te nsile applied stress is 1.7 MPa m(1/2). When the specimens are loaded in th e opposite direction, the stress is compressive at the notch rip and is ten sile some distance away from the notch tip. Ga atoms diffused to the tensil e zone and resulted in microcrack initiation. The microcrack propagated out wards in the tensile stress zone and was arrested at the compressive stress zone near the notch tip. The nominal compressive threshold stress intensit y K-IC*(L) is equal to 3.5 MPa m(1/2). The fracture surfaces of LME for ail the specimens are intergranular. (C) 1999 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.