Xe ions and Mo ions with 49-keV energy were implanted into an austenite stainless steel at doses between 1x10 1 5 and 35x10 1 5 ionscm - 2 . Grazing incidence X-ray diffraction was used to analyze the surface structure of implanted sample. Xe implantation went through differentiation of two types of austenite crystallites and formation of constrained ferrite. For low implantation doses, Mo first inserted into austenite cells inducing austenite lattice expansion. Then, as the Mo dose increased, this expansion was combined with the differentiation of two types of austenite crystallites. Above 6x10 1 5 ionscm - 2 a new bcc structure appeared: a ferrite with Mo was formed. High dose implantation leads to partial amorphisation.