(中南大學(xué)，材料科學(xué)與工程學(xué)院 長沙 410083)
摘 要: 對一種含少量Mg、Zn的Al-Cu-Li合金經(jīng)過T6(固溶+人工時效)和T8(固溶+預(yù)變形+人工時效)熱處理后的顯微組織進行研究。結(jié)果表明：該合金在(T6, 170 ℃)峰時效時析出大量的立方相，而在(T6, 120 ℃)和(T6, 190 ℃) 峰時效時卻沒有發(fā)現(xiàn)立方相的大量存在。T1相和立方相之間可能存在一種競爭析出關(guān)系，而溫度和預(yù)變形因素制約著這種競爭析出關(guān)系。利用Monte Carlo方法模擬時效初期該合金的原子分布，分析其立方相的形成機理。模擬結(jié)果表明：在(T6, 170 ℃)峰時效初期，Mg-Zn團簇周圍的Cu、Mg原子富集區(qū)成為立方相形成的理想形核點。同時，Mg團簇周圍區(qū)域內(nèi)較高的空位濃度也有利于溶質(zhì)原子的快速擴散。因此，Mg-Zn原子團簇應(yīng)是立方相形核的關(guān)鍵因素。
關(guān)鍵字: Al-Cu-Li合金；立方相；熱處理；Monte Carlo方法；原子團簇輔助形核
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The Al-Cu-Li alloys with addition of trace elements of Mg and Zn, treated by T6(solution treatment+artificial aging)and T8(solution treatment+pre-deformation+artificial aging), were studied. The experiment results show that a lot of new cubic phases precipitate when the alloy is aged under the peak-aged condition of (T6, 170 ℃), but this case dose not be found in the alloys aged under the peak-aged conditions of (T6, 120 ℃) and (T6, 190 ℃). There exists a competitive precipitation relationship between T1 phase and cubic phase, which is restricted by the factors of temperature and pre-deformation. Monte Carlo method was used to simulate the atom distribution in the alloy during initial aging stage and analyze the forming mechanism of the cubic phase. The simulation results show that during the initial aging stage of (T6, 170 ℃), the Cu-Mg atom enrichment zones around Mg-Zn clusters become the perfect nucleate points for the cubic phase formation. Meanwhile, the higher vacancy concentration around Mg clusters is beneficial to quick solute diffusion. Thus, the Mg-Zn atom clusters may be the key factor of the formation of cubic phase.
Key words: Al-Cu-Li alloy; cubic phase; heat treatment; Monte Carlo method; cluster-aided-nucleation
