(111) Au-Ni multilayers have been deposited by molecular beam epitaxy on a (100) Cu buffer on (100) Si. At constant composition (1:1) and total thickness, the substrate interaction stress deduced from wafer curvature measurements is increasing with the superperiod (9-52 Angstrom). It is tensile and varies between 200 and 400 MPa. The largest period sample has been studied in detail. Wavy interfaces are evidenced by transmission electron microscopy. A detailed stress analysis by X-ray diffraction shows that Au is under compressive stress (-1.25 GPa) and Ni under tensile stress (+1.43 GPa). Whereas the stress-free lattice parameter for Au is found to be the bulk one, a tensile expansion is found in Ni. This is tentatively attributed to Au intermixing.