Epitaxial Si1-xGex (0 less than or equal to x less than or equal to 1) multilayers, grown on Si(001) at 350 degrees C using a hot-wire assisted gas source molecular beam epitaxy, were observed by HRTEM. Two sample preparation techniques are compared : Ar+ ion milling and tripod thinning, It is shown that the first one gives rise to an important crystalline reorganization whereas the second one provides a large cross-section suitable for HRTEM investigations, We focused our studies on two kinds of interfaces : Ge-Si and Si-Ge. It appears that the Si layer supports the main relaxation, resulting in a high density of stacking faults which allows the growth of a clean Ge upperlayer.