(1. 中南大學(xué)材料科學(xué)與工程學(xué)院，長沙 410083；
2. 中南大學(xué)粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
3. 中南大學(xué)有色金屬材料科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
4. 清華大學(xué)材料科學(xué)與工程學(xué)院，北京100084；
5. 北京科技大學(xué)材料科學(xué)與工程學(xué)院，北京100083；
6. 東北大學(xué)材料與冶金學(xué)院，沈陽110819)
摘 要: 基于第一性原理計(jì)算研究納米結(jié)構(gòu)鐵素體合金(NFAs)對中子輻照引發(fā)的氦的選擇性捕獲能力。結(jié)果表明：與鐵基體中的空位相比，氦更容易被NFAs中Y2Ti2O7的八面體間隙和Y2TiO5沿b軸方向的中空通道捕獲；被氧化物捕獲的氦相互間存在排斥作用，說明氦在NFAs中的分散度將在很大程度上取決于氧化物的析出分?jǐn)?shù)和彌散度；通過計(jì)算界面相圖推斷，鐵素體/Y2Ti2O7界面應(yīng)為富Y/Ti型，與實(shí)驗(yàn)觀測到的Y2Ti2O7析出相的非化學(xué)計(jì)量比特性吻合；氦對Fe/Y2Ti2O7界面有較強(qiáng)的偏聚傾向，且可能對氧化物顆粒尺寸敏感。較大尺度的Y2Ti2O7能夠?qū)⒑げ东@在界面和體內(nèi)，而低納米尺度的Y2Ti2O7更傾向于將氦捕獲在界面。
關(guān)鍵字: 納米結(jié)構(gòu)鐵素體合金；氦；Y2Ti2O7；Y2TiO5；第一性原理
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
3. Key Laboratory of Nonferrous Materials, Ministry of Education, Central South University, Changsha 410083, China;.
4. School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China;
5. School of Materials Science and Engineering, University of Science and Technology, Beijing 100083, China;
6. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China）
Abstract:First principles was studied for assessing the relative stabilities of transmutant helium trapping in Y2Ti2O7, Y2TiO5 and the ferrite matrix in nano-structured ferritic alloys (NFAs). The results suggest that, helium in NFAs prefers to occupy individual octa-interstitial sites of Y2Ti2O7 and the open channels along the b axis of Y2TiO5. The helium self-interaction in Y2Ti2O7 is essentially repulsive, suggesting that the dispersion of helium in NFAs might, to a large extent, depend on the number and dispersion of Y2Ti2O7 in the iron matrix. The calculated interface phase diagram predicts the ferritic/Y2Ti2O7 interfaces in NFAs as Y/Ti-rich, in agreement with the experimentally observed non-stoichiometric nature of Y2Ti2O7 precipitates in NFAs. Segregation tendency of helium to the ferritic/Y2Ti2O7 interface can be sensitive to the size of Y2Ti2O7.
Key words: nano-structured ferritic alloy; helium; Y2Ti2O7; Y2TiO5; first principle
