First-principles calculations on Al/AlB 2 interfaces

• Published in: Applied surface science Vol. 257; no. 17; pp. 7831 - 7836
• Main Authors: Han, Y.F., Dai, Y.B., Wang, J., Shu, D., Sun, B.D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2011
• Subjects: AlB 2; Aluminium alloys; First-principles calculation; Grain refining; Interface; First-principles calculation; Aluminium alloys; Grain refining; Interface; AlB 2
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.04.038

► We calculated Al/AlB 2 system to clarify heterogeneous nucleation potential of AlB 2. ► The outmost layer of AlB 2 particles prefers metal to metalloid atom termination. ► Al atoms continue the natural stacking sequence of bulk AlB 2 across interface. ► The interfacial energy of Al/AlB 2 is much larger than that of Al(s)/Al(l). ► Poor nucleation potency of AlB 2 is elucidated from thermodynamic considerations. The AlB 2 (1 1 1) surfaces and Al (1 1 1)/AlB 2 (0 0 0 1) interface were studied by first-principles calculations to clarify the heterogeneous nucleation potential of α-Al grains on AlB 2 particles in purity aluminium and hypoeutectic Al–Si alloys. It is demonstrated that the AlB 2 (0 0 0 1) surface models with more than nine atomic layers exhibit bulk-like interior, wherein the interlayer relaxations localized within the top three layers are well converged. The outmost layer of AlB 2 free surface having a preference of metal atom termination is evidenced by surface energy calculations. With Al atoms continuing the natural stacking sequence of bulk AlB 2, Al–Al metallic bonds are formed across interface during the combination of Al atoms with Al-terminated AlB 2 surface. The calculated interfacial energy of the Al/AlB 2 interface is much larger than that between the α-Al and aluminium melts, elucidating the poor nucleation potency of α-Al grains on AlB 2 particles from thermodynamic considerations.