Detailed microstructure of a cBN based cutting tool material

It is shown that this PCBN material consists of cBN both as micrometre-sized and nanometre-sized grains. The micrometre-sized grains show primarily straight phase boundaries and little reaction with the surrounding matrix. The matrix consists of mainly TiCN, with grains ranging from nanometres to sub-micrometres. The C and N content in TiCN varies, indicating a system far from equilibrium. Only small reaction zones are found and the major reaction is the one between Al and O, forming Al2O3. It is also shown that it is possible to prepare samples thin enough for TEM/EFTEM/EELS studies, enabling the study of minor reaction phases like TiB2.