The Research Of Microstructures And Mechanical Properties Of High Volume Fraction Titanium Matrix Composites Prepared By In-situ Synthesized Method

Particle reinforced Titanium based composites have a high specific strength,low density and high modulus,have been developed as a main stream of TMCs.In-situ synthesized methods have a clean interface compared to ex-situ methods,and brittle layers have been avoided.Therefore,In-situ synthesis was an one of the most optimized methods.This study aimed to develop high strength and high wear resistance materials,and the range from 10 vol.% to 35 vol.% TMCs have been prepared by PM and melting method,TA10 and TC4 alloys were designed as the matrixs respectively,TiC,TiB and(TiC+TiB)were chosen as the reinforcements.The effects of volume fraction on reinforcement morphology and distribution were studied,the variation of volume fraction on microstructure and mechanical properties were also studied;TA2,TA15 and TC4 welding materials were selected to study weldability of TMCs,through950 ? and 1050 ? annealing,the microstructural variation and micro-hardness were studied at high temperature.Finally,blades were poured and verified at actural working condition.The results of this study can be conclued as follow:(1)As the increasement of volume fraction,single TiC reinforced TMCs were hard to synthesized,the highest volume fraction reached 25 %.Through substitution addtion of boron,the synthesized difficulty was decreased.The volume fraction of(TiB+TiC)reached 35 %.(2)As the increasement of volume fraction,the morphology of TiC transform from Equiaxed particles to dendrites.TiB tranform from needle-like to plate-like.The variation of morphology was determined by crystal structure and solidification condition.(3)TC4 matrix composites have a higher microhardness than TA10 matrix composites,the highest hardness was 567 HV.The compression strength reached the peak value of 1874 MPa at 25 vol.%.(4)Welding microstructures by TC4 and TA15 alloy were better than that by TA2 alloy.Which were more suitable to weld TMCs.(5)Microhardness test showed that the hardness of TMCs welded by TC4 and TA15 was higher than that of matrix,and was equal to that of matrix by TA2 welding.(6)Through heat treatment,the TiC dendrites broke and was nodulizing,the distribution of TiC was more homogenious,but the hardness of TMCs has a weak change.(7)TMCs blade was casted and applied at working condition,the result showed no crack on the casting,and the service life extended.The expected aim was completed successfully.