New iron rich metal alloys containing aluminum and copper along with specific amounts of boron are disclosed. The alloys are subjected to rapid solidification processing (RSP) technique which produces cooling rates between .about.10.sup.5 to 10.sup.7 .degree.C./sec. The as-quenched ribbon, powder etc. consists primarily of a metastable crystalline solid solution phase. The metastable crystalline phases are subjected to suitable heat treatments so as to produce a transformation to a stable multiphase microstructure which includes borides; this heat treated alloy exhibits superior mechanical properties with good corrosion and/or oxidation resistance for numerous engineering applications.