论文部分内容阅读
使用分离式Hopkinson压杆(SHPB)系统,在温度293~973K、应变率6 000~10 000s-1下,对原位合成TiC颗粒和TiB晶须混合增强钛基复合材料(TMCs)的动态压缩性能进行了研究。试验结果表明:在373~573K、673~773K和873~973K范围内TMCs流变应力随温度的增加而显著减小;在较低温度(低于373K)和较低应变率(6 000~8 000s-1)下,TMCs呈现小幅的应变率硬化特征,而在较高温度(573K及以上)时各应变率下TMCs均存在应变率软化特征,且温度越高材料应变率软化效应越明显。材料失效/断裂机制分析表明:应变率软化机制主要是绝热软化及其产生的绝热剪切带(ABS)中微裂纹的形成和扩展的综合作用;在较高的应变率和较大应变下ABS中会产生微裂纹,温度较低时TMCs塑性不足以抑制或阻碍微裂纹的扩展,从而导致TMCs在宏观上迅速破坏;材料破坏时以钛合金基体塑性断裂为主,但在局部伴随部分增强相脆性断裂。
The dynamic compression of titanium matrix composites (TMCs) reinforced with in-situ synthesized TiC particles and TiB whiskers was carried out with a split Hopkinson pressure bar (SHPB) system at a temperature of 293-973 K and a strain rate of 6 000-10 000 s-1 Performance has been studied. The experimental results show that the flow stress of TMCs decreases with the increase of temperature at 373-573K, 673-773K and 873-973K. At lower temperature (lower than 373K) and lower strain rate (6 000-8 Tensilim and TMCs exhibited a small rate of strain hardening characteristic under the low temperature (000s-1). While at higher temperature (573K and above), TMCs had the strain rate softening characteristics, and the higher the temperature, the more obvious the material strain rate softening effect. The analysis of material failure / fracture mechanism shows that the mechanism of strain rate softening is mainly the adiabatic softening and the combined effect of formation and propagation of microcracks in the adiabatic shear band (ABS). At higher strain rate and larger strain, ABS The microcracks will be generated. When the temperature is low, the plasticity of TMCs is not enough to restrain or hinder the propagation of microcracks, which leads to the macroscopical damage of TMCs. When the material is damaged, the plastic deformation of the TMCs is dominated. However, Brittle fracture.