Ductile-to-brittle transition for the aluminum alloy contacting to liquid gallium metal

This work elucidates the effect of various amounts of liquid Ga (e.g., 0.2–5 mg) on the fracture behavior of Al alloy. The relationship between the tensile properties and the various amounts of Ga in the sample was studied by conducting tensile tests. Additionally, the fracture mode of the sample is observed by field-emission scanning electron microscopy. The tensile test results indicated a clear distinction between samples with amounts of Ga that are above and below the critical amount, 1 mg. When the amount of Ga was less than 1 mg, the maximum tensile load of the samples was slightly lower than that of the samples without Ga, and extensive ductile fracturing was observed. However, when the amount of Ga exceeded 1 mg, the tensile load was markedly lower. Complete intergranular fracture occurred on the fracture surfaces. Moreover, energy dispersive spectrometry analysis revealed that the IGa/IAl ratio clearly increased with the amount of Ga over 1 mg, such that intergranular fracture of the AA6061 sample occurred when the critical value of Ga applied to the sample was greater than or equal to 1 mg and the IGa/IAl ratio exceeded or equal to 0.3.