本文選題：第一原理 + 鈦合金�。� 參考：《遼寧大學》2017年碩士論文

【摘要】：從發(fā)現(xiàn)鈦合金優(yōu)秀力學性能起,人們對它的研究就從未止步。由中科院沈陽金屬研究所開發(fā)的新型鈦合金Ti2448是一款新型醫(yī)用鈦合金。該合金表現(xiàn)出了更卓越的力學性能,不過對其微觀變化機理還不明確。本文采用基于密度泛函理論的第一原理計算方法,運用VASP軟件包對βTi-Nb合金的電子結(jié)構(gòu)進行初步研究的基礎(chǔ)上,繼續(xù)對不同構(gòu)型下不同Nb含量的βTi-Nb合金的電子結(jié)構(gòu)進行更細致的理論計算。為研究Ti2448合金的微觀機制的分子動力學模擬和開發(fā)勢函數(shù)提供數(shù)據(jù)支持。本課題組初步計算過程中發(fā)現(xiàn)βTi-Nb在Nb含量為35at%~65at%之間對Vegard定律有明顯的偏移。我們的計算針對的是Nb含量在這一范圍內(nèi)的βTi-Nb合金。通過結(jié)合能的計算發(fā)現(xiàn)合金穩(wěn)定性隨著Nb含量的增加而提高,合金不易形成有序相;隨著Nb含量的增加,態(tài)密度圖中的贗能隙變寬,費米能級降低說明合金不易氧化,抗氧化性升高;合金的分波態(tài)密度對比發(fā)現(xiàn)βTi-Nb合金體系的態(tài)密度主要由Ti-Nb的d軌道電子提供;為了更加直觀的了解原子間成鍵情況,本文計算了βTi-Nb合金的電荷差分密度并繪制了差分電荷密度圖,分析發(fā)現(xiàn):Nb-Nb鍵之間表現(xiàn)出較強的共價性,形成很強的共價鍵,所以隨著Nb含量的增加合金中電子的局域性和方向性增強,結(jié)構(gòu)也更加穩(wěn)定;在計算βTi-Nb合金的電子結(jié)構(gòu)的同時,還計算了Ti-Nb基體中的雜質(zhì)間的相互作用。結(jié)果表明:Nb基體中Ti雜質(zhì)間具有相互排斥作用,而在Ti基體中的Nb雜質(zhì)具有相互吸引的作用。
[Abstract]:Since the discovery of excellent mechanical properties of titanium alloys, the study of titanium alloys has never stopped. A new titanium alloy Ti2448 developed by Shenyang Institute of Metals of Chinese Academy of Sciences is a new medical titanium alloy. The alloy exhibits more excellent mechanical properties, but the mechanism of microcosmic change is not clear. In this paper, the first principle method based on density functional theory is used to study the electronic structure of 尾 Ti-Nb alloy by using VASP software package. The electronic structures of 尾 Ti-Nb alloys with different NB contents in different configurations were calculated in detail. It provides data support for molecular dynamics simulation and development potential function of micromechanism of Ti2448 alloy. During the preliminary calculation of 尾 Ti-Nb, we found that 尾 Ti-Nb deviated from Vegard's law obviously between the NB content of 35atum and 65at%. Our calculations are for 尾 Ti-Nb alloys with NB content in this range. Through the calculation of binding energy, it is found that the stability of the alloy increases with the increase of NB content, and the ordered phase is not easily formed, and with the increase of NB content, the pseudo-energy gap in the density of states diagram becomes wider, and the decrease of Fermi energy level indicates that the alloy is not easy to oxidize. The density of states of 尾 Ti-Nb alloy system is mainly supplied by the d-orbital electrons of Ti-Nb alloy system, and in order to understand the bonding between atoms more intuitively, the density of states of 尾 Ti-Nb alloy system is mainly supplied by the d-orbital electrons of Ti-Nb alloy system. In this paper, the charge differential density of 尾 Ti-Nb alloy is calculated and the differential charge density diagram is plotted. It is found that there is a strong covalent bond between the 2: Nb-Nb bonds, and a very strong covalent bond is formed. Therefore, with the increase of NB content, the electron localization and directivity in the alloy become more stable, and the interaction between impurities in Ti-Nb matrix is also calculated while the electronic structure of 尾 Ti-Nb alloy is calculated. The results show that the Ti impurity is mutually repulsive and the NB impurity in the Ti matrix is attractive to each other.
【學位授予單位】：遼寧大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.23

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