New types of particle feedstocks and heterogeneous grain structures are provided for rare earth permanent magnets (REPMs) and their production in a manner to significantly enhance toughness of the magnet with little or no sacrifice in the hard magnetic properties. The novel tough REPMs made from the feedstock have heterogeneous grain structures, such as bi-modal, tri-modal, multi-modal, laminated, gridded, gradient fine/coarse grain structures, or other microstructural heterogeneity and configurations, without changing the chemical compositions of magnets.