Effects Of Additive Compositions On Microstructure Evolution And Mechanical Properties Of (Ti,V,M)C-based Cermets

Carbide cermets prepared by powder metallurgy process play an important role in the field of wear resistance.Titanium cermet tools have a good surface finish and stable high temperature performance,but there is still a gap between their toughness and tungsten-based hard alloys.The poor wettability of TiC and metal bonding phase is the main reason for its brittleness.Addition of transition metal carbides can improve the wettability of carbides and bonding phases,and improve the overall performance of titanium-based cermets.Carbide additives are divided into two types according to the crystal structure.The carbides different from the TiC crystal structure have a large solubility,which is conducive to promoting liquid phase sintering.The carbides with the same crystal structure as TiC are easy to form solid solutions,but the difference in metal atomic radius greatly affects the dissolution of carbides.The composite addition of carbides can more effectively improve the comprehensive performance of titanium-based cermets through synergy.The crystal structure of VC and TiC is the same,and the atomic radii of V and Ti are similar.The ideal solid solution can be formed when the Hume-Rothery rule is satisfied.V atoms replacing Ti atoms do not affect the stability of the crystal structure and are randomly arranged inside the crystal.Based on the above ideas,this paper combined the Vickers hardness,flexural strength test,SEM&EDS electron microscope observation and XRD phase detection system to study the effects of additive components on the evolution and mechanical properties of?Ti,V,M?C-based cermets.Firstly,the effects of VC additives on the microstructure and mechanical properties of?Ti,V,M?C-based cermets were studied in the carbides added.Based on the previous basic research,the control of the thickness of the coating phase is beneficial to improve the comprehensive performance.When the sintering process is the same,the thickness of the cladding phase depends on the dissolved carbide content in the binder phase.The optimized distribution ratio was obtained by adjusting the content of VC and binding phase:when the VC content was 4wt%and the Co-Ni content was 15wt%,the microstructure of the?Ti,V,M?C-based cermet was coated with the ring phase The thickness is the smallest,the bending strength is 1370MPa,the Vickers hardness is 1669N/mm²,and the comprehensive mechanical properties reach the best.Secondly,based on the optimized composition of VC,the effects of additives on the microstructure evolution and mechanical properties of?Ti,V,M?C-based cermets were studied according to the different crystal structure of carbides.Mo/Mo₂C and WC have the largest solubility in the binder phase among transition group metal carbides different from the TiC crystal structure.The total additions of Mo and WC and the effects of Mo/WC are systematically studied.The results show that when the total amount of Mo and WC is 6wt%and Mo/WC is 1:1,the bending strength of?Ti,V,M?C-based cermet is 1370MPa,and the Vickers hardness is 1669N/mm²..When the content of NbC was further compounded by2wt%,the comprehensive mechanical properties of?Ti,V,M?C-based cermets reached the optimum,the bending strength was 1394MPa,and the Vickers hardness was 1665N/mm².