Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials
Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials
复制标题
DOI：
10.1038/s41467-019-08752-7
复制
发表时间：
2019-02-26
影响因子：
16.6
通讯作者：
Gault, Baptiste
中科院分区：
文献类型：
--
作者：
Chang, Yanhong;Lu, Wenjun;Gault, Baptiste
在商业纯Ti （CP-Ti）和Ti基合金中，通过传统方法（如电抛光和室温聚焦离子束（FIB）铣削）制备的微观观察中，经常观察到氢吸附导致氢化物形成。在这里，我们证明了低温FIB铣削可以有效地防止不希望的氢气吸收。采用低温温度为-135℃的氙气等离子体FIB显微镜制备了CP-Ti和Ti双相合金（Ti- 6al - 2sn - 4zr - 6mo, Ti6246, wt.%）的样品。透射电子显微镜（TEM）、选择区域电子衍射和扫描电子显微镜（sem）显示，CP-Ti薄片未形成氢化物。原子探针断层扫描进一步证明，与传统方法相比，冷冻fib显著降低了Ti6246基体内的氢含量。在分子动力学模拟的支持下，我们发现显著降低H扩散的热活化可以抑制制备过程中不希望的环境氢吸收，并防止预充氢扩散出样品，从而允许在纳米尺度上研究ti基合金的氢脆机制。
Hydrogen pick-up leading to hydride formation is often observed in commercially pure Ti (CP-Ti) and Ti-based alloys prepared for microscopic observation by conventional methods, such as electro-polishing and room temperature focused ion beam (FIB) milling. Here, we demonstrate that cryogenic FIB milling can effectively prevent undesired hydrogen pick-up. Specimens of CP-Ti and a Ti dual-phase alloy (Ti-6Al-2Sn-4Zr-6Mo, Ti6246, in wt.%) were prepared using a xenon-plasma FIB microscope equipped with a cryogenic stage reaching -135 degrees C. Transmission electron microscopy (TEM), selected area electron diffraction, and scanning TEM indicated no hydride formation in cryo-milled CP-Ti lamellae. Atom probe tomography further demonstrated that cryo-FIB significantly reduces hydrogen levels within the Ti6246 matrix compared with conventional methods. Supported by molecular dynamics simulations, we show that significantly lowering the thermal activation for H diffusion inhibits undesired environmental hydrogen pick-up during preparation and prevents pre-charged hydrogen from diffusing out of the sample, allowing for hydrogen embrittlement mechanisms of Ti-based alloys to be investigated at the nanoscale.