To enable sustainable carbon-free fusion energy, managing reactor structural material degradation during normal operation as well as accident scenarios is vital. Tungsten (W) plasma-facing materials (PFMs) are susceptible to aggressive high-temperature oxidation during air-ingress fusion reactor accidents, yet there's a lack of oxidation kinetic data for irradiated tungsten. Here, we utilize atmospheric environmental transmission electron microscopy (ETEM) to present the first kinetic data for substrate-free W nanofuzz oxidation at 400 °C and 500 °C in 1 bar dry air. Comparison with pristine bulk W during the early parabolic stage suggests an irradiation-decelerated oxidation for W nanofuzz. Our time-resolved in-situ characterization reveals a durable amorphous surface oxide, likely promoted by high-flux He irradiation-induced surface defects, serving as an effective passivating layer that impedes nanofuzz oxidation onset. This surface oxide layer also interfaces well with newly formed orthorhombic WO, facilitated by stress relief through He bubble shrinkage, providing lasting passivating protection throughout the nanofuzz parabolic oxidation. This new finding challenges conventional notions of irradiation's negative impact on metal oxidation, and calls for advanced characterization to enhance our understanding of fusion energy materials degradation, informed by further accident modeling.

中文翻译：

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大气压下面向等离子体的钨纳米绒氧化的原位 ETEM 研究：微观结构演化和无基材氧化动力学


为了实现可持续的无碳聚变能源，在正常运行和事故情况下管理反应堆结构材料的退化至关重要。钨 (W) 面向等离子体材料 (PFM) 在进气聚变反应堆事故期间容易受到剧烈的高温氧化，但缺乏辐照钨的氧化动力学数据。在这里，我们利用大气环境透射电子显微镜 (ETEM) 展示了在 1 bar 干燥空气中 400 °C 和 500 °C 下无基质 W 纳米绒毛氧化的第一个动力学数据。与早期抛物线阶段的原始块体钨的比较表明，钨纳米绒毛发生了辐照减速氧化。我们的时间分辨原位表征揭示了一种耐用的非晶表面氧化物，可能是由高通量氦辐照引起的表面缺陷促进的，作为阻止纳米绒毛氧化开始的有效钝化层。该表面氧化层还与新形成的斜方晶系 WO 良好界面，通过 He 气泡收缩来消除应力，从而在整个纳米绒毛抛物线氧化过程中提供持久的钝化保护。这一新发现挑战了辐照对金属氧化产生负面影响的传统观念，并呼吁通过进一步的事故建模来进行先进的表征，以增强我们对聚变能材料退化的理解。