Study On Preparation Technology And Properties Of Mo₂FeB₂-based Cermets

Mo₂FeB₂-based cermets are widely used in industry of tools and dies because of their excellent properties such as high hardness and strength.Mo₂FeB₂-based cermets were prepared in vacuum sintering furnace using Mo,Fe,FeB and other additives as raw materials.The solid-state sintering mechanism of Mo₂FeB₂-based cermets,the effect of sintering process on the structure and properties of Mo₂FeB₂-based cermets,and the effect of Ti(C,N)and Ti C addition on the structure and properties of Mo₂FeB₂-based cermets were studied.The phase and microstructures of Mo₂FeB₂-based cermets during solid-state sintering were studied.The results show that with the increase of sintering temperature,two-step reaction takes place.Fe₂B was formed from 600?to 700?and Mo₂FeB₂ was formed from 700?to 950?.Mo₂FeB₂ was basically completely reacted at 950?.During the solid-state sintering of Mo₂FeB₂-based cermets,with the increase of temperature,the volume of the cermets will first appear smaller thermal expansion.Then,with the reaction proceeding,the sintering neck between the particles will form and grow up gradually.The pore will change from irregular shape to tunnel shape.The temperature will continue to rise,the pore closure will become isolated closed pore,the pore will gradually become smaller,and the sintered body will gradually retract.Shrinkage and compactness.The effect of sintering process on the structure and properties of Mo₂FeB₂-based cermets was studied.The results show that with the increase of temperature,the hard phases in the structure grow and form gradually,and the voids are discharged gradually.The sintered samples are basically compact and uniformly distributed at 1160?.The comprehensive mechanical properties of cermets are the best.The anisotropy of Mo₂FeB₂ leads to the columnar growth of Mo₂FeB₂ hard phase along the C axis.The effects of Ti(C,N)and Ti C addition on the structure and properties of Mo₂FeB₂-based cermets were studied.The results show that the addition of Ti(C,N)makes the hard phase particles of Mo₂FeB₂-based cermets grow irregularly,and the agglomeration of various phases in the structure is serious and the distribution of the structure is uneven,which leads to the appearance of a large number of pores.Therefore,adding Ti(C,N)solid solution will reduce the performance of Mo₂FeB₂-based cermets.When 1%Ti C is added,the grain size of hard phase of Mo₂FeB₂-based cermets can be refined and the structure is more uniform.The main reason is that the fine Ti C particles are dispersed and distributed in the matrix.The dispersion strengthening of Mo₂FeB₂-based cermets makes the structure more uniform.On the other hand,Ti C as nucleating agent promotes the nucleation of Mo₂FeB₂,which mainly distributes at the boundary of Mo₂FeB₂ grain hinders the continuation of its grain.Grow up.When the amount of Ti C is increased and the sintering temperature is increased,the annular phase of Ti C can be observed in the structure when the sintering temperature reaches 1340?.The small particles are dissolved in the hard phase of Mo₂FeB₂and the large particles are at the boundary of the hard phase of Mo₂FeB₂.The nucleation and growth of Ti C annular phase at grain boundary seriously affects the growth of hard phase Mo₂FeB₂,which leads to the transformation of its morphology from equiaxed to irregular shape.