中文摘要：

采用超重力下燃烧合成技术,制备出TiB2-TiC共晶复合陶瓷。XRD、SEM与EDS结果表明,复合陶瓷主要由大量细小的TiB2片晶均匀分布于TiC基体上的共晶组织构成,而富钛ε碳化物（Ti,Cr）C1-x则断续分布于TiC基体间,同时在基体中还孤立分布着少量的、形态不规则的α-Al2O3晶粒或Al2O3-ZrO2共晶团组织。高温化学反应使所有产物均呈液态,且超重力的引入诱发熔体内部Stocks流,从而获得液态Ti-Cr-C-B与液态氧化物的分层熔体,液态Ti-Cr-C-B在远离平衡态下发生共晶反应生成TiB2-TiC共晶复合陶瓷。性能测试表明,随着B4C＋Ti＋C在燃烧体系中质量分数增加,TiB2-TiC共晶复合陶瓷相对密度和断裂韧性变化不大,分别为97%～99%与6.5～7.1 MPa.m1/2,而维氏硬度与弯曲强度则逐渐增加,最高可达28.6 GPa与615 MPa。

英文摘要：

TiB2-TiC eutectic composite ceramics were prepared by combustion synthesis under high gravity.XRD,SEM and EDS results show that TiB2-TiC composites are mainly composed of the eutectic microstructures of TiC matrix,in which a large number of the fine TiB2 platelet grains are dispersed uniformly;meanwhile,at the boundaries of the eutectic microstructures there discontinuously disperse the ε-carbides with the enrichment of Ti atoms,and a few of isolated,irregular α-Al2O3 grains and Al2O3-ZrO2 colonies are also observed.Because high-temperature chemical reaction results in the full-liquid products,and the introduction of high gravity induces the Stocks flow in the melts,leading to the formation of layered melts consisting of liquid Ti-Cr-C-B and liquid oxides,it is considered that TiB2-TiC composites grow through eutectic transformation far away from the equilibrium state.The results of properties indicate that with increasing mass fraction of B4C＋Ti＋C in combustion systems,the relative density and fracture toughness of TiB2-TiC composites are all among 97%~99% and 6.5~7.1 MPa·m1/2,respectively,and the Vickers hardness and flexural strength are increased gradually to the maximum values of 28.6 GPa and 615 MPa,respectively.