(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 以Miedema混合焓模型為基礎(chǔ)，計(jì)算Al-Er和Si-Er二元合金的部分熱力學(xué)函數(shù)，如混合焓∆H，過剩熵SE以及過剩吉布斯自由能GE以及各組元的活度。結(jié)合Al-Er和Si-Er二元相圖計(jì)算了Al3Er和Er5Si3相析出反應(yīng)的吉布斯自由能。結(jié)果表明：Al-Er和Si-Er二元合金的混合焓、過剩自由能與過剩熵在整個(gè)濃度范圍內(nèi)均為負(fù)值，各組元活度計(jì)算結(jié)果相對(duì)于理想熔體有較大的負(fù)偏差，說明Er原子與Al原子和Si原子都有很強(qiáng)的相互作用； Al3Er和Er5Si3相反應(yīng)的吉布斯自由能均為負(fù)值，且Er5Si3相的反應(yīng)吉布斯自由能比Al3Er相的小，因此Er加入到Al-Si合金中會(huì)優(yōu)先與Si生成Er5Si3相，過剩的Er才與Al生成Al3Er相。
關(guān)鍵字: Al-Er；Si-Er；Miedema混合焓模型；活度
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Based on the Miedema formation enthalpy model, the enthalpies of formation, excess entropies, excess free-energy and the activity among all components of Al-Er and Si-Er binary alloy were calculated. The results show that their values are all negative. Compared to an ideal solution, the activity has a larger negative bias, which indicates that Er has stronger interaction with Al and Si. According to the binary phase diagram of Al-Er and Si-Er, the Gibbs free-energy of the precipitation of Al3Er and Er5Si3 are deduced. The Gibbs free-energy of reaction of Al3Er is lower than that of Er5Si3, so Er5Si3 forms priority to Al3Er, and then the excess Er reacts with Al and form Al3Er.
Key words: Al-Er; Si-Er; Miedema formation enthalpy model; activity
