Effect of Titanium Content on the Microstructure and Mechanical Properties of Tungsten-Titanium Alloy

摘要:

采用粉末冶金方法制备了4种钛含量分别为0.5%，1.0%，1.5%和2.0%的新型钨钛合金，分析了钛含量对钨钛合金微观组织以及高应变率加载条件下的动态力学性能的影响机理。结果表明，钛颗粒以不同形貌分布于钨合金的镍铁粘结相中，钛颗粒直径是影响钛颗粒微观形貌的主要因素。当钛颗粒直径大于20 μm时，钛颗粒中存在大量微观孔洞。钛颗粒在粉末冶金液相烧结过程中没有发生熔化以及溶解现象，但与钨颗粒和粘结相的界面结合较好。霍普金森压杆动态压缩实验结果表明，当动态加载应变率为3700 s-1时，钛含量为0.5%的钨钛合金具有较高的动态压缩屈服强度，而当钛含量由1.0%增加到2.0%时，动态压缩屈服强度减小趋势减缓。钛含量为2.0%的钨钛合金在高应变率加载条件下，在于轴向成45°方向上出现绝热剪切带。在绝热剪切带内部，钛颗粒发生伸长变形并且钛颗粒中的微观孔洞相互连接导致钛颗粒碎化。由于钛具有较低的导热率，与钛相连的钨颗粒热软化区温度身高幅度要高于常规钨-镍-铁合金，热软化效应加剧导致钛元素的加入以及含量的增加提高了钨合金的绝热剪切敏感性。

Abstract:

Tungsten heavy alloys (WHAs) with four different titanium contents (0.5%, 1.0%, 1.5%, 2.0%, wt.%) were prepared by powder metallurgy. The influence of titanium content on the microstructure and mechanical properties under high strain rates were investigated. The results show that the titanium particles disperse in the matrix with different morphology and the main effective element is the diameter of the titanium particles. There are lots of micro holes in the titanium particles when the diameter of titanium particles is larger than 20 μm. The titanium particles do not dissolve in the matrix during the sintering process and the interfaces between titanium and tungsten, titanium and matrix are good. The results of Hopkinson Striker Bar indicate that the dynamic compressive strength is highest when the content of titanium is 0.5% and the strength has little change as the content of titanium increases from 1.0% to 2.0% under 3700 s-1 strain rate. In the WHA with 2.0% titanium content, the adiabatic shear banding (ASB) is the main deformation mode and the titanium in the ASB is fragile, the temperature of thermal softening area is higher than that of the traditional WHAs because of the existence of titanium particles. The addition of titanium in the WHAs improves the adiabatic shear banding susceptivity.