Fabrication of bulk cores of nano-crystalline Fe84.3Si 4B8P3Cu0.7 alloy with a lamellar type of microstructure is reported. Amorphous ribbon flakes of size ∼1.0-2.0 mm were compacted in the bulk form by spark plasma sintering technique at different sintering temperatures. High density (∼96.4%) cores with a uniform nano-granular structure made from α-Fe (∼31 nm) were obtained. These cores show excellent mechanical and soft magnetic properties. The lamellar micro-structure is shown to be important in achieving significantly lower magnetic core loss than the non-oriented silicon steel sheets, commercial powder cores and even the core made of the same alloy with finer and randomly oriented powder particles.