EFFECT OF GRAIN SIZE ON SURFACE MORPHOLOGY AFTER FOCUSED ION BEAM MICRO-MACHINING FOR CEMENTED CARBIDES

Abstract

The cemented carbides containing various microstructures were machined by scanning a 30 keV Ga + ion beam, with a nominal spot size of 300 nm and a current of 5300 pA, from side to side and up and down and a 100 μs pixel dwell time. In the coarse-grained cemented carbide, the surfaces of the WC phase parts were very smooth while those of the Co phase were rough. In the fine-grained cemented carbides, the surfaces were smoother on the whole and the irregularities were smaller compared with the coarse-grained cemented carbides. It is indicated that preparation of cemented carbide with finer WC grains, and decrease of the mean free path of Co phase are required for the FIB micro-machining to reduce surface irregularities.