From suppressed void growth to significant void swelling in NiCoFeCr complex concentrated solid -solution alloy
From suppressed void growth to significant void swelling in NiCoFeCr complex concentrated solid -solution alloy
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DOI：
10.1016/j.mtla.2020.100603
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发表时间：
2020-03-01
期刊：
影响因子：
3.4
通讯作者：
Zhang, Yanwen
中科院分区：
文献类型：
--
作者：
Fan, Zhe;Yang, Tai-ni;Zhang, Yanwen
空心膨胀会导致核反应堆的尺寸不稳定，影响反应堆的安全运行。目前抑制空洞膨胀的策略主要是通过引入高密度缺陷汇来增强缺陷吸收和重组。复杂的浓固溶体合金（csa），包括高熵合金，由于其固有的化学复杂性而没有界面，可以承受严重的辐射损伤。然而，csa中抑制空洞的潜在机制尚不清楚。在本研究中，我们研究了在3mev Ni离子辐照下等原子NiCoFeCr中空洞的演化与辐照深度、剂量和温度的关系。在相对较低的剂量（16和54位移/原子，dpa）下，空洞主要在离子损伤区外形成，峰值损伤区的空洞形成受到抑制，导致溶胀可以忽略不计。然而，随着剂量的进一步增加（86 ~ 250 dpa），峰值损伤区出现了明显的空洞生长，并以延长的位错线为主，而不是低剂量时形成的短位错线和环。500 ~ 700℃时，位错密度减小，位错增大。从500℃到580℃，在54 dpa的温度下，整体空洞膨胀急剧增加，但峰值损伤区域的空洞增长仍然受到抑制。从抑制孔洞生长到显著孔洞膨胀的转变归因于位错演化和局部化学不均匀性（Fe/Cr在基体中的富集）。研究表明，通过调节化学复杂度来控制元素扩散和缺陷演化，可以进一步提高csa的抗膨胀性能。
Void swelling can result in dimensional instability and undermine the safe operation of nuclear reactors. Current strategies to inhibit void swelling mainly focus on enhancing defect absorption and recombination by introducing high-density defect sinks. Complex concentrated solid-solution alloys (CSAs), including high-entropy alloys, can withstand severe radiation damage due to their inherent chemical complexity without interfaces. However, the underlying mechanisms for void suppression in CSAs are far from clear. In this research, we studied the void evolution with respect to irradiation depths, doses, and temperatures in equiatomic NiCoFeCr under 3 MeV Ni ion irradiations. At relatively low doses (16 and 54 displacements per atom, dpa), voids form mainly outside of the ion-damaged region, and void formation in the peak damage region is suppressed, leading to negligible swelling. However, with further increase of dose (86 up to 250 dpa), significant void growth occurs in the peak damage region and extended dislocation lines dominate instead of short dislocation lines and loops formed at lower doses. From 500 to 700 C, the dislocation density decreases while dislocations grow. Although the overall void swelling increases dramatically from 500 to 580 C at 54 dpa, void growth in the peak damage region is still suppressed. The transition from suppressed void growth to significant void swelling is attributed to dislocation evolution and local chemical inhomogeneity (enrichment of Fe/Cr in the matrix) at higher doses. Our study shows that controlling element diffusion and defect evolution through tuning chemical complexity can further enhance the swelling resistance of CSAs.