Fabrication and microstructure analysis of Ti₃AlC₂-CBN composites

Ti₃AlC₂-CBN composites are fabricated by spark plasma sintering using Ti₃AlC₂ and CBN powders as raw materials.Effect of CBN size and mass fraction on the phase composition and microstructure of the composites are studied.The results show that the main phases of the sample containing 10wt% CBN are Ti₃AlC₂,CBN and TiC.When CBN mass fraction is higher(20wt%-40wt%),TiC,TiN,AlN and TiB₂ phases are formed.It is also shown that with 10wt% or 20wt% CBN,transition layer with a thickness of about 10 μm is formed on the surface of the CBN,while with 30 wt% or 40wt% CBN,there is no transition layer between CBN and the matrix.Many pores appear in the composite containing 10wt% CBN with a size of about 10 μm,whose main phase is TiC equiaxed grains with 1-2 μm transition layer on the surface of CBN.In conclusion,as CBN content increases or its mass fraction size decreases,CBN reacts more with Ti₃AlC₂,thus producing a thinner transition layer.