An analytical method to extract irradiation hardening from nanoindentation hardness-depth curves
An analytical method to extract irradiation hardening from nanoindentation hardness-depth curves
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DOI：
10.1016/j.jnucmat.2017.10.049
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发表时间：
2018-01-01
影响因子：
3.1
通讯作者：
Roberts, S. G.
中科院分区：
文献类型：
--
作者：
Kareer, A.;Prasitthipayong, A.;Roberts, S. G.
第四代核反应堆计划为新的核能系统提供了潜力，这将大大提高安全性和可靠性、可持续性、反应堆寿命、防扩散能力和盈利能力[1]。在这些设计中，预计将比当前商业反应堆具有更高的操作温度（> 900 C）和更高的中子剂量（30-100 dpa）[2][3]。铁素体/马氏体和ODS钢是这些反应器的结构部件的候选材料，因为它们具有高屈服强度、低活化性和较高的抗溶胀性[4]。已知暴露于辐照的金属由于弗伦克尔对缺陷簇的产生而硬化，弗伦克尔对缺陷簇在施加的应力下充当位错运动的障碍[5]。这种硬化增加了材料的屈服强度σy，但降低了延展性并导致脆化[6][7][8]。因此，表征辐照后的机械性能并量化所观察到的机械性能变化对于这些反应堆的安全设计至关重要。传统的机械测试方法，使用毫米或厘米大小的样品，在考虑放射性材料时，由于与处理活性材料相关的严格规定，因此需要专门的设施，成本高，耗时长。离子辐照已成功地用作模拟中子辐照损伤的替代品，提供了在更短的时间尺度（即数天而不是数年）内无放射性的高度损伤样品[9]。由此产生的离子辐照微结构包含高密度的辐照诱导缺陷，主要是位错环，与中子辐照材料中观察到的损伤相当[10][11]。与使用离子辐照相关的主要缺点是所获得的受损材料的体积限于浅表面层（小于几微米），并且以每原子位移（dpa）测量的损伤程度或剂量在该层的厚度上变化很大。使用高能离子束或质子辐照，可以在一定程度上增加该层的深度，最多可达几十微米;但是测量以单一特定剂量辐照的靶材料的机械性能是复杂的，因为总是会对宽范围的剂量进行采样。小规模的机械测试方法仍然是在一个非均匀剂量范围内取样的性质[12]。
The Generation IV nuclear reactor initiative provides the potential for new nuclear energy systems that will significantly improve safety and reliability, sustainability, reactor life, proliferation resistance and profitability [1]. In these designs, higher operating temperatures (> 900 C) and much higher neutron doses (30-100 dpa) than in current commercial reactors are expected [2][3]. Ferritic/martensitic and ODS steels are candidate materials for the structural components of these reactors due to their high yield strength, reduced activation and higher swelling resistance [4]. Metals exposed to irradiation are known to harden due to the generation of Frenkel pair defect clusters that act as obstacles to dislocation motion under an applied stress [5]. This hardening increases the yield strength, σy, of the material but reduces the ductility and causes embrittlement [6][7][8]. Therefore characterising the mechanical properties and quantifying the changes observed in the mechanical properties post irradiation is essential for the safe design of these reactors.Traditional methods of mechanical testing, using millimetre-or centimetre-size specimens can be costly and time consuming when considering radioactive materials due to the stringent regulations associated with handling active materials and thus the need for specialist facilities. Ion-irradiation has successfully been used as a surrogate to emulate neutron irradiation damage, providing highly damaged samples that are non-radioactive in much shorter timescales (ie a number of days rather than years)[9]. The resulting ion-irradiated microstructure contains a high density of irradiation-induced defects, primarily dislocation loops, comparable to the damage observed in neutron-irradiated material [10][11]. A major drawback associated with using ion-irradiation is that the volume of damaged material obtained is restricted to a shallow surface layer (less than a few microns) and the extent of damage or the dose, measured in displacements per atom (dpa), varies strongly through the thickness of this layer. The use of high-energy ion beams, or proton irradiation, can increase the depth of this layer to some extent, up to a few tens of microns; but measurement of the mechanical properties targeting material irradiated to a single specific dose is complicated because a wide range of doses will always be sampled. Small-scale mechanical test methods still sample the properties of a range of non-uniform dose [12].