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鎢中溶質(zhì)原子鉻與空位的相互作用的第一性原理計(jì)算研究
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1.四川大學(xué);2.中國工程物理研究院材料研究所

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國家自然科學(xué)基金資助(項(xiàng)目號51501119)


Study of the interaction between the solute Cr atoms and vacancy in W-Cr alloys using first-principles calculation
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    摘要:

    鎢鉻(W-Cr)合金具有優(yōu)異的物理性能,被認(rèn)為是面向等離子體材料(PFM)中最有潛力的候選材料。而合金元素對輻照損傷演化過程的影響規(guī)律是鎢合金優(yōu)化設(shè)計(jì)的關(guān)鍵,深入研究溶質(zhì)原子與輻照缺陷(如:空位)的相互作用有助于理解輻照損傷演化的微觀物理機(jī)制。本文基于第一性原理方法,對W-Cr合金的溶質(zhì)原子Cr占位、Cr與空位的相互作用及Cr含量對其影響規(guī)律進(jìn)行了計(jì)算研究。發(fā)現(xiàn)相比于間隙位置,原子Cr更易占據(jù)置換位置,W中溶質(zhì)Cr有偏聚的趨勢;在輻照環(huán)境下,空位和自間隙原子均易與溶質(zhì)原子Cr相結(jié)合,易加速W中富Cr相的析出;隨Cr含量的增加,體系的形成能線性增加,因而結(jié)構(gòu)越發(fā)不穩(wěn)定。研究還發(fā)現(xiàn)超胞中單原子Cr的第二近鄰空位的形成能最低,且低于W的本征空位形成能,因而溶質(zhì)Cr與空位之間存在微弱的吸引;對于同一Cr含量,不同構(gòu)型的空位形成能及空位和Cr的結(jié)合能均不同,且Cr含量越高,數(shù)值越分散;隨著Cr含量的增加,平均空位形成能及空位與Cr的平均結(jié)合能均略有下降,因而溶質(zhì)原子Cr附近空位更易形成,空位濃度更高,同樣也表明溶質(zhì)Cr與空位有微弱的吸引。這些結(jié)論將有助于深入理解W中溶質(zhì)元素存在條件下輻照缺陷演化過程的微觀物理機(jī)制。

    Abstract:

    Tungsten-chromium alloy (W-Cr alloy) is a primary candidate for plasma-facing materials (PFM) in future fusion devices because of its excellent properties. The knowledge of the interaction between solute Cr atoms and vacancy in W-Cr alloys is the key to understand the mechanism of the evolution of radiation damage. In this work the occupation of solute Cr atoms, the interaction between solute Cr atoms and vacancy, and the effect of the solute Cr concentration were studied by first-principles calculation. We found that the solute Cr atoms prefers to occupy the substitutional position with formation energy of ~0.3eV. The point defects induced by radiation will facilitate the segregation of the solute Cr atoms. The formation energy of solute Cr increases linearly with increasing of the concentration of solute Cr, indicating a strong segregation. It was also found that there exists a very weak attractive interaction between the solute Cr atoms and vacancy, and the interaction tends to be stronger when the concentration of the solute Cr increases. These results are important for understanding the long-term micro-structural evolution of materials under irradiation.

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何梓薦,黃雪飛,樂國敏,付寶勤.鎢中溶質(zhì)原子鉻與空位的相互作用的第一性原理計(jì)算研究[J].稀有金屬材料與工程,2020,49(8):2691~2696.[He Zijian, Huang Xuefei, Le Guomin, Fu Baoqin. Study of the interaction between the solute Cr atoms and vacancy in W-Cr alloys using first-principles calculation[J]. Rare Metal Materials and Engineering,2020,49(8):2691~2696.]
DOI:10.12442/j. issn.1002-185X.20190625

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  • 收稿日期:2019-07-30
  • 最后修改日期:2019-09-06
  • 錄用日期:2019-09-06
  • 在線發(fā)布日期: 2020-09-27
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