A turbomachine rotor wheel including blades made of composite material; an annular mounting plate; a plurality of composite material blades mounted on the mounting plate, each blade also including a top platform at its tip carrying radial labyrinth teeth; an orientation disk fastened coaxially around the mounting plate and including at its outer periphery a plurality of axial slots that are open at one end, each slot presenting a cross-section that matches the cross-section of a blade root so as to hold it angularly in position by co-operation of shapes; and a variable-diameter spring ring housed in part in an axial notch formed in each blade root and projecting axially relative thereto, the spring ring to come into radial abutment against an inside surface of the orientation disk during radial outward movement of the blades relative to the mounting plate.