(湖南大學(xué) 材料科學(xué)與工程學(xué)院, 長(zhǎng)沙 410082)
摘 要: 采用第一原理贗勢(shì)平面波方法，計(jì)算了Mg17Al12相Ca合金化前后的能態(tài)與電子結(jié)構(gòu)。計(jì)算結(jié)果顯示： 當(dāng)Ca分別置換Mg17Al12相中Mg(Ⅰ)、 Mg(Ⅱ)和Mg(Ⅲ)原子時(shí)， (Mg17-xCax)Al12相 (x=0, 1, 4, 12) 的負(fù)生成熱逐漸升高、 結(jié)合能逐漸增大， 表明Ca置換Mg17Al12相中Mg(Ⅲ)原子時(shí)其Ca合金化能力最強(qiáng)，合金化后形成的(Mg5Ca12)Al12相結(jié)構(gòu)穩(wěn)定性最高。電子態(tài)密度(DOS)分析結(jié)果表明： Ca合金化后Mg17Al12相結(jié)構(gòu)穩(wěn)定性升高的主要原因是由于合金化后來自Al(p)和Ca(s)的價(jià)電子使其在低能區(qū)的成鍵電子數(shù)增多。
關(guān)鍵字: Mg17Al12相； 贗勢(shì)平面波方法； 結(jié)合能； 電子結(jié)構(gòu)
Ca alloying Mg17Al12 phase
（ School of Materials Science and Engineering, Hunan University,
Changsha 410082, China）
Abstract: Using the first-principle pseudopotential plane-wave method, the energy and electronic structures of Ca alloying Mg17Al12 phase were investigated. The results show that the negative formation heat and the cohesive energy of
(Mg17-xCax)Al12 (x=0, 1, 4, 12) phases gradually increase when the Mg atoms at Ⅰ, Ⅱ, Ⅲ positions of Mg17Al12 phase are substituted by Ca respectively, which indicates that for the alloying ability of (Mg17-xCax)Al12(x=0, 1, 4, 12) phase the replacement of Ca for Mg(Ⅲ) atoms is the strongest among the above three substitutions, and the (Mg5Ca12)Al12 phase formed by this manner has the highest structural stability. After compared the densities of states (DOS) of
(Mg17-xCax)Al12 phases, it is found that the increase of the structural stability of Mg17Al12 phase alloyed by Ca attributes to an increase in the bonding electron numbers at lower energy level below Feimi level, which mainly originates from the contribution of valence electron numbers of Al(p) and Ca(s) orbitals.
Key words: Mg17Al12 phase; pseudopotential plane-wave method; cohesive energy; electronic structure
