The role of the T 1 phase in the pre-exposure and hydrogen embrittlement of AlLiCu alloys

Abstract

A series of slow strain rate tests were conducted on longitudinal specimens of two AlLi binary and two AlLiCu alloys, to determine the possibility of embrittlement by hydrogen and to investigate the role of the T 1 phase in the embrittlement process. The binary AlLi alloys were not embrittled. The copper-containing alloys were susceptible to hydrogen embrittlement that can be induced by pre-exposing in NaCl solution or simultaneous cathodic charging and straining. It was shown that the T 1 phase facilities hydrogen entry into the copper-containing alloys and is responsible for their susceptibility. The hydrogen embrittlement susceptibility of the different microstructures of the two AlLiCu alloys was found to correlate very well with the amount of T 1 present and the slip behavior. The fracture mode was mainly transgranular. Some secondary intergranular cracking was also present and its extent related to the amount and distribution of hydrogen present.