|About this Abstract
||2020 TMS Annual Meeting & Exhibition
||Refractory Metals 2020
||Pressureless Sintering and Microstructure Evolution of Ultrafine-grained Tungsten
||Yanhao Dong, Xingyu Li, Lin Zhang, Ju Li
|On-Site Speaker (Planned)
Pressureless sintering of refractory metals is a cost-effective way to produce large parts with complex geometry, yet it is not easy especially when ultrafine grain sizes are preferred. Here we report interesting low-temperature pressureless sintering data of pure tungsten (99.9%) in flowing hydrogen, ending with 99% theoretical density, 700 nm grain size and uniform microstructure. No texture, abnormal grain growth, second-phase impurities or grain-boundary liquids were observed. We found parabolic grain growth in dense samples and calculated grain boundary mobility deviates from Arrhenius-type relationship showing apparent transition at 1400 oC. As a result, sintering below 1400 oC is more favored with respect to grain growth, which provides phenomenological explanation for our low-temperature sintering data. Lastly, Vickers hardness and its Weibull modulus of low-temperature sintered samples are greatly improved, due to finer and more uniform microstructure. Parallel studies are in progress for other refractory metals and shall be discussed as well.
||Planned: Supplemental Proceedings volume