An assembly of a member, made of a first material in an aperture of a part, made of a second material having no plastic domain, using an intermediate part made of a third material, mounted between the member and the part. The intermediate part includes a hole for receiving the member. The part includes pierced holes forming a deformation mechanism distributed around the aperture thereof. The elastically and plastically deformed intermediate part radially grips the member and stresses the elastic deformation mechanism of the part so as to secure the assembly in a manner that is not destructive for the part. Such an assembly can for example be used in the field of timepieces.