The magnetization reversal in a ferromagnetic material occurs by (in)-coherent rotations or through magnetic domain wall movements. Both mechanisms rely on intrinsic and extrinsic, i.e. microstructure dependent, parameters. Experimentally we can measure the intrinsic properties (saturation magnetization (M<SUB>s</SUB>), magnetocrystalline anisotropy and Curie point) in any polycrystalline material and the extrinsic properties of a magnet (coercivity (H<SUB>c</SUB>), remanence, energy product (BH)max) in specific nanostructured samples. To get high-energy permanent magnets the materials must present high saturation (M<SUB>s</SUB>
>100A·m<SUP>2</SUP>/kg) and anisotropy (H<SUB>a</SUB> >5T), but also high extrinsic properties, like (BH)max >200kJ/m<SUP>3</SUP>. We are reviewing the effect of the modification of the microstructure on the coercivity of RE-lean magnets. In 2:14:1 phases, after infiltration, we can obtain values of coercivity (H<SUB>c</SUB> =2.5T), which represent a large fraction of the anisotropy field (≈37%). However, for 1:12-phases, the coercivity is still low, around H<SUB>c</SUB> =0.5T, for samples with H<SUB>a</SUB> >10T.