细晶钨合金的制备与动态失效行为

Fabrication of fine-grain tungsten heavy alloy and its dynamic failure behavior

采用喷雾干燥-热还原的方法制备纳米级93W-4.9Ni-2.1Fe复合粉末,并以其为原料制备出含0.03%Y2O3(质量分数)的细晶钨合金,研究微量稀土掺杂对烧结致密化和显微组织的影响以及93W-4.9Ni-2.1Fe合金在动态压缩状态下的力学行为。结果表明:纳米级复合粉末在1380～1410℃之间液相烧结可实现材料的近全致密化,比同种成分的传统钨合金的烧结温度降低了120℃左右,合金的相对密度可达99%以上,且合金的晶粒尺寸为5μm左右。与传统W-Ni-Fe合金相比,细晶W-Ni-Fe合金在高应变率下具有更高的合金强度和延性,同时,在较低应变率下有形成局部绝热剪切带的倾向;添加微量Y2O3能进一步提高细晶W-Ni-Fe合金的绝热剪切敏感性,有利于在较低应变率下形成绝热剪切带。

Fine-grain（FG） 93W-4.9Ni-2.1Fe alloy containing 0.03%Y2O3（mass fraction） was obtained via liquid phase sintering of nano-composite powders prepared by spray drying,subsequent thermal reduction process.The influence of Y2O3 on sintering behavior and microstructure and the dynamic mechanical properties and dynamic failure were studied.The results show that the near full densification is realized and the finer spherical-shape tungsten grains with the size of about 5 μm in the alloy are obtained during liquid phase sintering in the range from 1 380 ℃ to 1 410 ℃,which is 120 ℃ lower than that of the traditional tungsten heavy alloys,and the relative density of the alloy reaches over 99%.Compared with traditional tungsten heavy alloys,the fine-grain tungsten heavy alloy possesses higher yield strength and larger elongation at high strain rate,and promotes the tendency to adiabatic shear band（ASB） formation at lower strain rate.On the basis mentioned above,adding Y2O3 can further increase the sensitivity of ASB of fine-grain W-Ni-Fe alloy,which is more beneficial to form obvious ASB at lower strain rate.