(1. 上海交通大学 金属基复合材料国家重点实验室，上海 200240；
2. 宝山钢铁股份有限公司 特殊钢分公司，上海 200940)
摘 要: 采用普通的熔炼方法，利用钛与B4C之间的化学反应制备7715D钛基复合材料。将该复合材料热加工后得到具有网篮组织的TiC和TiB混合增强的钛基复合材料，在900~1 050 ℃、初始应变速率为10−2~3×10−4 s−1时采用材料试验仪测量该钛基复合材料的力学性能。结果表明：该复合材料的室温和高温力学性能均有提高。在1 000 ℃、应变速率为3×10−4 s−1时，所得复合材料的最大伸长率为625%，其真应力—真应变曲线呈二次硬化现象，该复合材料超塑变形性能良好。计算所得表观激活能为359~473 kJ/mol；超塑变形过程中的动态再结晶是网篮钛基复合材料获得较高伸长率的重要原因；合适的应变速率能促使网篮钛基复合材料发生动态再结晶，而合适的温度则能在促进超塑变形的同时限制晶粒长大；动态再结晶和晶粒的长大使真应力—真应变曲线中出现二次硬化现象。
关键字: 钛基复合材料；网篮组织；超塑性；二次硬化；动态再结晶
（1. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200420, China;
2. Special Steel Branch, Baoshan Iron and Steel Co. Ltd., Shanghai 200940, China）
Abstract:TiB and TiC reinforced 7715D titanium matrix composite (TMC) was produced by reaction between titanium and B4C through casting high-temperature synthesis reactions. Then by hot processing this composite, TiB and TiC reinforced 7715D titanium matrix composite with basket-weave structure was obtained. The optical microstructure of this titanium matrix composite was investigated, the mechanical properties and superplastic tensile tests under 900−1050 ℃ and 10−2−3×10−4 s−1 were also carried out. The results show that the composite has basket-weave structure, its mechanical properties under room-temperature and high-temperature are both improved, and its superplasticity is also good, with maximum elongation of 625% at 3×10−4 s−1 and 1 000 ℃, and with second work hardening effect during deformation process. The activate energy (Q) calculated fluctuates among 359−473 kJ/mol. The proper temperature can accelerate the superplastic deformation of this composite while restrain its grain size growth, and suitable initial strain rate promotes dynamical recrystallization. Dynamical recrystallization during superplastic deformation is the key reason that the basket-weave structured titanium matrix composite has high extensibility, and along with grain growth, it result in the second hardening effect in true stress─true strain curves.
Key words: (TiB+TiC)/7715D composite; basket-weave structure; superplasticity; second hardening effect; dynamically recrystallization
