(1. 煙臺(tái)南山學(xué)院 材料科學(xué)與工程學(xué)院，煙臺(tái) 265713；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
3. 中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要: 基于密度泛函理論的第一性原理方法，計(jì)算研究了7系鋁合金亞穩(wěn)η′相→穩(wěn)定η2相轉(zhuǎn)變過(guò)程中主元素的行為和作用。計(jì)算結(jié)果表明：η′→η2相轉(zhuǎn)變過(guò)程伴隨Al原子的排出，主要源于基體中Cu和過(guò)剩Mg原子對(duì)η′相中Al原子的固溶置換。Cu和Mg固溶可以提高η′相的穩(wěn)定性，但過(guò)量固溶可能會(huì)抑制η′→η2相轉(zhuǎn)變，甚至形成其他富Cu/Mg析出相。實(shí)驗(yàn)表征的η2/Al界面應(yīng)為Zn終端型結(jié)構(gòu)。基體中的Cu、過(guò)剩Mg和Zn均會(huì)偏析到界面上的間隙位，促使η2相長(zhǎng)大。
關(guān)鍵字: η′相；η2相；相轉(zhuǎn)變；主合金元素；界面；第一性原理
（1. School of Materials Science and Engineering, Yantai Nanshan University, Yantai 265713, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The behaviors and roles of major alloying elements on the metastable η′ phase to stable η2 phase transformation in aged 7XXX Al alloys were investigated by first-principles method based on density-functional-theory (DFT) calculation. The calculation results show that the η′→η2 transformation is accompanied with the consistent release of Al atoms from η′ phase, mainly due to the strong Cu and Mg substitution of Al inside η′. These substitutions help to stabilize η′ in the matrix, but excessive substitution may inhibit η′→η2 transformation and even induce other Cu/Mg-rich precipitate phases. The experimentally-observed η2/Al interface is deduced to Zn-terminated structure. Cu and excess Mg and Zn in the matrix tend to segregate to the interstitial sites of the interface, promoting the growth of η2 phase.
Key words: η′ phase; η phase; phase transformation; major alloying element; interface; first-principles
