Influence of hot pressing sintering temperature and time on microstructure and mechanical properties of TiB2/TiN tool material

In this paper, a TiB2/TiN composite was produced by the hot pressing sintering method. The effect of hot pressing parameters on the TiB2/TiN composite microstructure and mechanical properties was investigated. The results show that the fracture toughness and flexural strength of the composite increase firstly and then decrease with an increase of the sintering temperature. The flexural strength of the composite increases firstly and then decreases with an increase of the sintering time, while the fracture toughness increases consistently with an increase of the sintering time. The microstructure was revealed by the means of SEM and TEM. The results show that the TiB2 grain size and density increase with an increase of the sintering temperature and time. There are irregular shape grains at 1530 degrees C sintering temperature for 90 min sintering time. New phase of MoNi is found in the composite. Ni element increases in the vicinity around TiN particles with the increasing temperature. In the sample prepared at 1620 degrees C temperature, many dislocations can be found. (C) 2012 Elsevier B.V. All rights reserved.