The invention relates to a method for examining a two-phase titanium alloy with an alpha phase and a beta phase. The method comprises the following steps consisting in: (a) cutting a sample from a part made from the alloy; (b) preparing a region (4) of the cut surface of the sample close to the edge (50) thereof, said edge (50) being shared with the outer surface (1) of the part so that the region (4) can be observed; (c) observing the alpha phase of the region (4) at a magnification of more than 5000x; (d) determining whether or not grains are present in the alpha phase of a first area (11) adjacent to the edge (50) of the sample; and (e) when grains are absent from the alpha phase of the adjacent area (11) but grains (22) are present in the alpha phase outside said adjacent area (11), concluding that the alloy is contaminated by a gas.
