Microstructure and densification of the Ti6Al4V-70%TiB2 metal-ceramic by coupled multi-physical fields-activated sintering

摘要

In this study, a novel sintering method, named as coupled multi-physical fields activation sintering was introduced for the sintering of Ti6Al4V/TiB2 metal ceramics with an extremely high content of TiB2 and the effects of the processing parameters on the microstructures and densification of the metal ceramics were investigated. It is found that a relative density, 97.10%, of the sintered sample can be achieved when the case of temperature 1500 degrees C, heating rate 30 degrees C/s, pressure 125 MPa and dwell time 4mins, is used. Microstructures and grain boundary characteristics of the sintered samples indicate that the densification process is closely associated with the formation of a large amount of TiB nano particles and the formation of liquid Ti phase. The TiB nano particles are formed in the Ti matrix due to the reaction between Ti and TiB2 particles while the liquid phase is produced because of a great deal of Joule heat generated in the interface between Ti and TiB2 particles. TiB2-Ti-TiB and TiB2-Ti-TiB2 grain boundary structures are also formed during the densification process due to the interaction between the TiB2 and Ti. The capillary force on the formation of the liquid phase and the reactive sintering at the interface significantly enhance the densification process. (C) 2019 Elsevier B.V. All rights reserved.