This study reveals that thermal fatigue loading (transient thermal shock), similar to that in fusion environments, can serve as a surface processing technique for BCC metals. Regions with a {110} grain orientation can be selectively achieved in varying sizes and locations on the sample surface. Furthermore, our experiments confirm that the specific localized orientation transformation obtained through this method exhibits certain high-temperature stability at 1573 K (above the recrystallization temperature of tungsten). The experiment employed a 0.25 GW/m² high-energy pulsed electron beam for 1 ms to cyclically load the tungsten surface, simulating edge localized mode events in fusion conditions. It was found that tungsten exhibited significant surface grain orientation transformation (distinct {110} grain orientation) under low strain (∼ 1 %) after transient thermal shocks, a phenomenon rarely mentioned in studies of thermal shock on fusion reactor divertor materials. Microstructure characterization results suggest that this localized orientation transformation, induced by minor surface damage, primarily results from the generation, movement, and evolution of dislocations into subgrain and low-angle grain boundaries. The cyclic accumulation of the migration of kink-like subgrain/low-angle grain boundaries under transient thermal stress at high temperatures drives this process. Subsequently, crystal plasticity finite element method simulations based on dislocation slip were conducted to study the surface grain orientation transformation of tungsten under compressive thermal stress. This predictive capability provides valuable guidance for understanding the service conditions of fusion reactor divertor materials. Furthermore, we propose that cyclic transient thermal shocks can serve as an effective surface processing technique for metals, enabling the formation of specific localized grain orientations.

中文翻译：

---

热应力驱动位错和小角度晶界偏移在热冲击下钨表面塑性变形和晶粒取向演变中的作用


这项研究表明，类似于熔融环境中的热疲劳载荷（瞬态热冲击）可以作为 BCC 金属的表面处理技术。具有{110}晶粒取向的区域可以在样品表面上以不同的尺寸和位置选择性地实现。此外，我们的实验证实，通过该方法获得的特定局部取向转变在 1573 K（高于钨的再结晶温度）下表现出一定的高温稳定性。该实验使用 0.25 GW/m² 高能脉冲电子束 1 ms 来循环加载钨表面，模拟聚变条件下的边缘局部模式事件。研究发现，在瞬态热冲击后，钨在低应变 （∼ 1 %） 下表现出显着的表面晶粒取向转变（{110}晶粒取向不同），这种现象在聚变反应堆分流器材料的热冲击研究中很少提及。微观结构表征结果表明，这种由轻微表面损伤诱导的局部取向转变主要是由于位错产生、移动和演变为亚晶粒和小角度晶界的结果。在高温下瞬态热应力下，扭结状亚晶粒/小角度晶界迁移的循环积累推动了这一过程。随后，进行了基于位错滑移的晶体塑性有限元方法模拟，研究了压缩热应力作用下钨的表面晶向转变。这种预测能力为了解聚变反应堆分流器材料的使用条件提供了有价值的指导。 此外，我们提出循环瞬态热冲击可以作为金属的有效表面处理技术，从而能够形成特定的局部晶粒取向。