( 1. 廣西大學 物理科學與工程技術(shù)學院，南寧 530004;
2. 中國科學院 國際材料物理中心， 沈陽 110016)
摘 要: 運用固體經(jīng)驗電子理論(EET)， 對Al-Li合金時效初期的若干偏聚晶胞的價電子結(jié)構(gòu)進行了計算。 計算結(jié)果表明： 不包含空位的偏聚晶胞的鍵絡最強鍵為Al—Al鍵， 其中Al原子的共價半徑較Li原子的共價半徑要大； 而含空位的偏聚晶胞的最強鍵為Al—Li鍵， Al原子的共價半徑要比Li原子的共價半徑要小； 在空位存在的情況下， 由于Al原子與Li原子的電負性相差明顯， 促使Al和Li原子結(jié)合， 傾向形成Al-Li短程序結(jié)構(gòu)偏聚區(qū)， 這種含空位的短程序結(jié)構(gòu)很可能就是δ′(Al3Li)亞穩(wěn)相的前兆結(jié)構(gòu)和生長胚胎； 由于Al-Li-空位有序偏聚晶胞的Al—Li鍵絡比基體鍵絡要強許多， 因此， 淬火過程中合金生成的Al-Li-空位偏聚晶胞對合金過飽和固溶體起主要強化作用； 后續(xù)析出的δ′(Al3Li)亞穩(wěn)相鍵絡各項異性顯著， 鍵絡強度明顯提高； 由于Al3Li與基體共格， 其大量均勻彌散析出起到提升基體整體鍵絡強度， 同樣對合金產(chǎn)生強化作用。
關鍵字: Al-Li合金; Al3Li; 空位; 價電子結(jié)構(gòu); 力學性能
LAN Zhi-qiang1, LIU Hui1, WEI Yin-yan1
（ 1. School of Physics Science and Technology,
Guangxi University, Nanning 530004, China;
2. Center of International Materials and Physics,
Chinese Academy of Sciences, Shenyang 110016, China）
Abstract: The valence electron structures of the segregated cell of Al-Li alloy in earlier aging condition were calculated according to the empirical electron theory (EET) in solid. The results show: the strongest bond is the Al-Al bond in the segregated cell without containing vacancy, where the Al atomic covalence radius is greater than that of Li atom in the cell; while the strongest bond is the Al-Li bond in the segregated cell containing vacancy, and the Al atomic covalence radius in the cell is less than that of Li atom. Since the difference of electronagativity between the Al and Li atoms is obvious, it is inclined to formed the Al-Li segregated cell of short range order structure in the condition of vacancy present. The short range order structure containing vacancy is probably the embryo or precursor structure of the metastable phase δ′(Al3Li). Because the strongest covalent bond in the Al-Li-vacancy segregated cell in alloy formed in quenching is the main strength reason for supersaturated solid solution of alloy. The bond net of succeeding precipitation of δ′(Al3Li) has the picture of anisotropic Al-Al bonding and the bond intensity enhanced. Since the δ′(Al3Li) is coherence with matrix, the bond net strength is enhanced by the precipitation of δ′(Al3Li) and so strengthen the alloy.
Key words: Al-Li alloy; Al3Li; vacancy; covalence bond; mechanical properties
