Gong Peng, Kwok T W J, Wang Yiqiang, Dawson Huw, Goodall Russell, Dye David, Rainforth W Mark
Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK.
School of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Nat Commun. 2025 Mar 20;16(1):2746. doi: 10.1038/s41467-025-58042-8.
Fusion reactor materials for the first wall and blanket must have high strength, be radiation tolerant and be reduced activation (low post-use radioactivity), which has resulted in reduced activation ferritic/martensitic (RAFM) steels. The current steels suffer irradiation-induced hardening and embrittlement and are not adequate for planned commercial fusion reactors. Producing high strength, ductility and toughness is difficult, because inhibiting deformation to produce strength also reduces the amount of work hardening available, and thereby ductility. Here we solve this dichotomy to introduce a high strength and high ductility RAFM steel, produced by a modified thermomechanical process route. A unique multiscale microstructure is developed, comprising nanoscale and microscale ferrite, tempered martensite containing fine subgrains and a high density of nanoscale precipitates. High strength is attributed to the fine grain and subgrain and a higher proportion of metal carbides, while the high ductility results from a high mobile dislocation density in the ferrite, subgrain formation in the tempered martensite, and the bimodal microstructure, which improves ductility without impairing strength.
用于第一壁和包层的聚变反应堆材料必须具备高强度、耐辐射性且活化程度降低（使用后放射性低），这导致了低活化铁素体/马氏体（RAFM）钢的出现。目前的钢会遭受辐照诱导的硬化和脆化，对于计划中的商业聚变反应堆而言并不适用。要同时具备高强度、延展性和韧性很困难，因为抑制变形以产生强度的同时也会减少可用于加工硬化的量，从而降低延展性。在此，我们通过一种改进的热机械加工路线解决了这一矛盾，引入了一种高强度、高延展性的RAFM钢。这种钢形成了独特的多尺度微观结构，包括纳米级和微米级铁素体、含有细小亚晶粒和高密度纳米级析出物的回火马氏体。高强度归因于细晶粒和亚晶粒以及较高比例的金属碳化物，而高延展性则源于铁素体中高可移动位错密度、回火马氏体中的亚晶粒形成以及双峰微观结构，这种结构在不损害强度的情况下提高了延展性。
