XD TM method was used to prepare titanium aluminide(Ti 3Al) matrix composites. The phase constitution and the as cast microstructure of Ti 25Al alloy with different carbon contents have been investigated using XRD and SEM. Microhardness and elastic modulus of the matrix and reinforcements were tested by mechanical property microprobe. In Ti 25Al 0.5C alloy, blocky Ti 3AlC and lath Ti 3AlC were in situ formed as reinforcement, and homogeneously distributed in the matrix. The microhardness and elastic modulus of blocky Ti 3AlC are 14.2 GPa and 281.3 GPa respectively, higher than those of the lath Ti 3AlC about 3 GPa and 60 GPa respectively. When C content is more than 0.5%, dendritic TiC and Ti 3AlC were formed as reinforcement in a core structure, where the TiC core is coated with Ti 3AlC phase. The microhardness and elastic modulus of the reinforcement decrease with increasing distance from the center of the reinforcement and matrix. The maximum microhardness and modulus of TiC and Ti 3AlC are 22.8 GPa, 302.7 GPa and 20.2 GPa, 313.5 GPa, respectively.
展开▼
