中间钛片对TiB_2基陶瓷/钛合金梯度复合材料组织及性能的影响（英文）

Effects of Ti Sheet Insert on Microstructure and Properties of Graded Composites of TiB_2-based Ceramic and Ti-6Al-4V Alloy

在钛合金与陶瓷粉末之间引入厚度0.5~1.5mm的中间钛片,采用自蔓延离心熔铸工艺快速制备出了TiB_2基陶瓷/钛合金梯度复合材料。经过XRD、FESEM和EDS分析表明,添加钛片对陶瓷相没有明显的影响,但随着中间钛片厚度的增加,不仅细化陶瓷基体并改善其组织均匀性,而且增加了梯度界面厚度,减小甚至消除了钛合金基底热影响区。同时,热真空条件下液态陶瓷与钛合金之间发生熔化连接和原子互扩散,进而在凝固后期诱发TiB_2与Ti液的包晶反应TiB_2(s)+Ti(l)→2TiB(s),TiB自Ti液中的析晶反应和TiB与Ti液的共晶反应,实现了TiB_2的消减及TiB的生长,不仅改善了界面的残余应力,而且获得了陶瓷/钛合金多尺度多层次复合。界面组织结构的梯度演化与陶瓷/钛合金的热匹配不仅使梯度材料的硬度呈连续变化,而且使界面剪切强度达到了(316±25)MPa。

By inserting Ti sheet between ceramic powder and Ti alloy steel, （TiC -TiB_2）/Ti-6Al-4V graded composites were rapidly prepared by SHS centrifugal-casting process with different Ti sheet thickness from 0.5 to 1.5 mm. XRD, FESEM and EDS results show that there is no significant change in phase composition of the ceramic matrix after inserting Ti sheet, but the inserting promotes the microstructure refinement of the reaction products with the thickness increasing. Meanwhile, the introduction of Ti sheet not only enhances the thickness of the gradient interface, but also decreases the thermal infected zone of interface. Moreover, fusion bonding and atomic interdiffusion between liquid TiC -TiB_2 and excessive Ti liquid in thermal vacuum circumstances are considered to initiate peritectic reaction of TiB_2（s） ＋ Ti（l） → 2TiB（s）, direct growth of TiB solids from liquid Ti and eutectic reaction of TiB solids and liquid Ti at the final stage of joint solidification, so that consumption of TiB_2 solids and increase of TiB crystal relieve the interface residual stress, and the joint of the ceramic to Ti alloy is achieved in multilevel and multi-scale microstructure. The joint represents a transitional change in Vickers hardness and gets a high shear strength of （316±25） MPa between the ceramic and Ti alloy.