Sc在Al-Zn-Mg-Cu超高强铝合金中作用机理的电子理论研究

通过晶胞平移获得Al-Zn-Mg-Cu合金中α-Al，Al₃Sc及η相原子集团模型，采用自编软件建立α-Al/液态Al界面、α-Al/Al₃Sc界面原子团模型.用递归法计算合金中各组织的态密度、结合能、费米能级，合金元素Sc与空位相互作用能等电子参数.依据电子参数解释合金晶粒细化、腐蚀的物理本质.研究表明： Al₃Sc从液态金属析出时释放的能量比α-Al从液态金属析出时所释放的能量少，可先于α-Al从液态金属中析出；且α-Al 关键词： 电子结构 腐蚀 超高强Al合金

The electronic theory of the mechanism of the role of Sc in Al-Zn-Mg-Cu ultra high strength aluminium alloys

The atomic cluster models of α-Al, Al₃Sc,η phase in Al-Zn-Mg-Cu ultra high strength aluminum alloys have been constructed by cell translation and the atomic cluster models of the interfaces α-Al /liquid Al and α-Al /Al₃Sc have been set up by self-programmed software. The electronic structure parameters such as the density of states, the bonding energy of atom, the Fermi energy of the microscopic structure in alloys, the interaction energy between Sc and vacancy, have been calculated by recursion method. The physical nature of grain refinement and corrosion behavior of Al-Zn-Mg-Cu alloys has been explained according to the calculated electronic structure parameter. The results show that the energy given off by Al₃Sc precipitating from liquid Al is less than that by α-Al and Al₃Sc can precipitate from liquid Al prior to α-Al. Because of the lower interface energy of α-Al /Al₃Sc compared with α-Al /liquid Al, the Al₃Sc phase may offer the condition for the nucleation and growth of α-Al, which increases the nucleation rate of α-Al and refines the grain. The calculated results also indicate that Sc can attract the vacancy, decreasing the diffusion ability of vacancy and solute atoms, which makes the precipitate free zone along grain boundaries become narrower, and decreases the potential difference between grain and grain boundary, leading to the improvement of the corrosion resistance.