(1. 湖南大學 環(huán)境科學與工程學院，長沙 410082；
2. 湖南大學 材料科學與工程學院，長沙 410082；
3. 湖南省氣象局 氣象培訓中心，長沙 410125)
摘 要: 采用第一原理贗勢平面波方法研究跡量元素N在γ-Ni/γ′-Ni3Al相界區(qū)域的占位趨勢及其對相界斷裂強度的影響。結(jié)果顯示：以氣態(tài)形式存在的N不易摻雜到Ni/Ni3Al相界，而以固態(tài)形式存在的N則很容易被摻進Ni/Ni3Al相界；N在Ni/Ni3Al相界中不僅能穩(wěn)定存在，而且摻雜到八面體間隙比置換其中的基體原子具有更高的形成能力與結(jié)構穩(wěn)定性；N摻雜將削弱Ni/Ni3Al相界的斷裂強度，其中尤以間隙位摻雜最為明顯。電子結(jié)構分析表明：置換型摻雜時，相界斷裂強度的降低可歸結(jié)為Frenkel缺陷導致的摻雜相界層間電子相互作用的減弱；而間隙位摻雜，除了基體原子間電子相互作用因摻雜原子與基體原子間的強相互作用而減弱外，晶格畸變導致的局域彈性應變能增加也是一個重要的原因。
關鍵字: γ-Ni/γ′-Ni3Al相界；N摻雜；第一原理計算；脆化；電子結(jié)構
（1. College of Environmental Science and Engineering, Hunan University, Changsha 410082, China;
2. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
3. Hunan Meteorological Training Center, Hunan Meteorological Administration, Changsha 410125, China）
Abstract:Using a first-principles plane-wave pseudopotential method, the site preference of N and its influence on the fracture behavior of the γ-Ni/γ′-Ni3Al interface were investigated. The results show that the gaseous N2 is difficult to be joined into the Ni/Ni3Al interfacial region, but solid N impurity can be easily doped into the Ni/Ni3Al interface. The N-doped interfacial system can stably exist either for substitution for host atoms or for occupation at octahedral interstices, and N prefers to occupy the octahedral interstitial sites. N-doping, especially at octahedral interstitial sites, makes the fracture strength of the Ni/Ni3Al interface be weakened. For the substitutional interface, the N-induced embrittlement can be attributed to the decrease of electronic interactions between adjacent atomic layers caused by the Frenkel defect. While in the case of interstitial doping, a multiple influence of a decreasing electronic interaction between host atoms induced by a strong bonding between N and its nearest host atoms and a increased elastic strain energy originated from lattice distortion should be responsible for the harmful effect of N on strengthening of the Ni/Ni3Al interface.
Key words: γ-Ni/γ′-Ni3Al interface; N-doping; first-principle calculation; embrittlement; electronic structure
