Microstructure And Mechanical Properties Of TiC Particles Reinforced Titanium Matrix Composites

TiC/Ti-6Al-2.75Sn-3.5Zr-0.45Mo-0.75Nb-0.35Si composites were prepared by melting-casting process in this study. The composites are reinforced with 5% and 10% volume fraction of TiC respectively. TiC morphology,distribution as well as matrix morphology of as-cast and heat treatmen were investigated. The tensile properties at both room and elevated temperature were investigated on the compositesand, and then fracture mechanisms were studied.As cast, TiC in 5vol.%TiC/Ti composite is stripy or rod shape , the matrix is the lamellar; TiC morphology of 10vol.%TiC/Ti composite is equiaxed or near equiaxed, and the matrix is basketweave microstructure, With the increase of TiC content, the size of lamellar decreased.TiC in 5vol.%TiC/Ti composite, After 900℃/10h/WC heat treatment, is still stripy or rod shape, and the matrix is the lamellar; 1050℃/10h/WC , all the TiC is soluble in the matrix, and the matrix isαlamellae and acicular martensite; 1150℃/10h/WC, TiC is equiaxed and the matrix is acicular martensite. After 900℃/10h/FC heat treatment, TiC is stripy or rod shape; 1050℃/10h/FC, the number of TiC decreased; 1150℃/10h/FC, all the TiC is soluble in the matrix, and the matrix is the lamellar; with the temperature increasing, the size matrix expand.With the temperature increased, TiC in 10vol.%TiC/Ti composite dissolve obviously after 10h/WC, the diversification of the matrix morphology were lamellar,α+α′,small acicular martensite.TiC morphology of 10vol.%TiC/Ti composite dissolved more obviously with temperature increased after 10h/FC heat treatment. the diversification of the matrix morphology were lamellar,equiaxed,equiaxed.As the cooling rate increased, with 900℃/10h heat treatment, matrix morphology changed little; 1050℃/10h, the matrix of 5vol.%TiC/Ti composite, change from thick lamellar to acicular martensite, the matrix 10vol.%TiC/Ti composite vary from the equiaxed toα+α'; the diversification of matrix morphology with 1150℃/10h and 1050℃/10h heat treatment is similar.Tensile strength of the composite decreased, but the elongation has improved significantly under room temperature after heat treatment.the elongation of 5vol.%TiC/Ti composite is 2.99% after1150℃/10h/AC heat treatment.5vol.%TiC/Ti composite occur cleavage fracture under room temperature. 10vol.%TiC/Ti composites emerge quasi-cleavage fracture at both room and elevated temperature, some of the TiC particles cracked, instead of Debond with the matrix,and it account for that bonding strength of TiC and the matrix is very high.