Evolution of Nanocrystalline TiBCN Structure with Temperature and Mechanism

Evolution of the TiB0.71C3.32N0.79 quaternary nanocomposite structure at 600,700,800,900,and 1000℃ is investigated by high-resolution transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectrometry,and micro-hardness indentation.The nc-Ti(C,N)nanocrystallites exhibit the(200)preferential orientation and the amorphous carbon(a-C)phase gradually transforms into the crystallite graphite phase as the temperature is increased.At 1000℃,the nc-Ti(C,N)nanocrystallites increase to a size of 13 nm but the microhardness diminishes to 18-19 GPa.The corresponding mechanism is discussed.