(1. 上海交通大學(xué) 金屬基復(fù)合材料國家重點(diǎn)實(shí)驗(yàn)室，上海 200240；
2. 寶山鋼鐵股份有限公司 特殊鋼分公司，上海 200940)
摘 要: 采用普通的熔煉方法，利用鈦與B4C之間的化學(xué)反應(yīng)制備7715D鈦基復(fù)合材料。將該復(fù)合材料熱加工后得到具有網(wǎng)籃組織的TiC和TiB混合增強(qiáng)的鈦基復(fù)合材料，在900~1 050 ℃、初始應(yīng)變速率為10−2~3×10−4 s−1時(shí)采用材料試驗(yàn)儀測量該鈦基復(fù)合材料的力學(xué)性能。結(jié)果表明：該復(fù)合材料的室溫和高溫力學(xué)性能均有提高。在1 000 ℃、應(yīng)變速率為3×10−4 s−1時(shí)，所得復(fù)合材料的最大伸長率為625%，其真應(yīng)力—真應(yīng)變曲線呈二次硬化現(xiàn)象，該復(fù)合材料超塑變形性能良好。計(jì)算所得表觀激活能為359~473 kJ/mol；超塑變形過程中的動(dòng)態(tài)再結(jié)晶是網(wǎng)籃鈦基復(fù)合材料獲得較高伸長率的重要原因；合適的應(yīng)變速率能促使網(wǎng)籃鈦基復(fù)合材料發(fā)生動(dòng)態(tài)再結(jié)晶，而合適的溫度則能在促進(jìn)超塑變形的同時(shí)限制晶粒長大；動(dòng)態(tài)再結(jié)晶和晶粒的長大使真應(yīng)力—真應(yīng)變曲線中出現(xiàn)二次硬化現(xiàn)象。
關(guān)鍵字: 鈦基復(fù)合材料；網(wǎng)籃組織；超塑性；二次硬化；動(dòng)態(tài)再結(jié)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
