New Iron-Neodymium-Boron base alloys containing diboride based on zirconium, titanium or tantalum are disclosed. The alloys are subjected to rapid solidification processing technique which produces cooling rates between 10.sup.5 to 10.sup.7 .degree.C./second. The as-quenched filament, ribbon or particulate, powder etc. consists predominantly of a single amorphous phase. The amorphous powder is consolidated into bulk shapes by the method of hot extrusion. The bulk alloys consist of a ultrafine grained homogeneous crystalline phase dispersed with ultrafine sized particles of zirconium diboride, titanium diboride or tantalum diboride either singly or combined. The bulk alloys exhibit superior hard magnetic properties suitable for many engineering and scientific applications.