Grinding performance and delamination analysis of FeSiB metallic glass laminate

FeSiB metallic glass laminate is a state-of-the-art structure for magnetic core. Extremely high strength and hardness due to the amorphous matrix challenge its finishing process with severe tool wear and delamination. Meanwhile, grinding heat leads to crystallization of the material resulting in a magnetic deterioration. In this work, grinding data is presented for grind wheel wear, grinding force and surface quality when routing 7 mm thick FeSiB metallic glass laminate using electroplated CBN grinding points. Grinding experiments are carried out with grinding speeds of 0.5 and 1.5 m/s. Energy dispersive x-ray spectroscopy (EDS) and electron back scattered diffraction pattern (EBSD) analyses are conducted to inspect the delamination between the metallic foil layers and detailed microstructure of machined surface, respectively. The relation between the grinding force and delamination is discussed associated with the identification of crystallization condition near machined surface. As a result, severe plastic deformation between the layers and crystallization are identified which deteriorated the magnetic performance by inter-laminate circuit short and plastic strain. Load-displacement curve from nanoindentation confirmed the strain hardening level near machined surface.