以Al_4C_3、Ti和石墨粉为原料(Ti、Al、C的摩尔比为6:1:3),利用放电等离子烧结(SPS)技术通过原位反应制备出TiC/Ti_2AlC的复合材料.结果表明,基体相TiC的晶粒尺寸在2～5 μm左右,反应生成的Ti_2AlC颗粒尺度纵向长度为4～10 mm,横向宽度为1～2 mm,且弥散均匀分布在基体中.三元层状相Ti_2AlC的引入大大提高了复合材料的力学性能,复合材料的维氏硬度HV为11 GPa,断裂韧性K_(IC)为5.3 MPa·m~(1/2),抗弯强度sf为(470±50) MPa,弹性模量E为(228±30) GPa.通过压痕法观察了裂纹扩展路径,讨论了材料的断裂机制和增韧机制.材料以沿晶断裂为主,伴随少量穿晶断裂.
A mixture of Ti, Al_4C_3 and graphite powders was adopted to synthesize the TiC/Ti_2AlC composite using the spark plasma sintering-reactive synthesis method. The molar ratio of Ti: Al: C=6:1:3 was selected. The main microstructure consists of Ti_2AlC grains with 4～10mm in length and 1～2 mm in width and TiC grains with 2～5 mm. The composite shows improved mechanical properties at room temperature. The HV, K_(IC), sf and E is 11 GPa, 5.3 MPa·m~(1/2), (470±50) MPa, and (228±30) GPa respectively. The origin and propagating path of cracks under stresses were investigated by indentation method and SEM. The result shows that the cracking mechanism of TiC/Ti_2AlC composites is mainly intergranular crack accompanied by slight transcrystalline crack.
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