On the mechanism of grain refinement in Al–Zr–Ti alloys

• Published in: Journal of alloys and compounds Vol. 509; no. 1; pp. 57 - 60
• Main Authors: Atamanenko, T.V., Eskin, D.G., Sluiter, M., Katgerman, L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05.01.2011; Elsevier
• Subjects: Alloys; Aluminum alloys; Aluminum base alloys; Cavitation; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Grain refinement; Intermetallics; Materials science; Nucleation; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; Supercooling; Titanium; Titanium base alloys; Ultrasound; Intermetallics; Aluminum alloys; Nucleation; Cavitation; Ultrasound; Grain refinement; Aluminium base alloys; Material processing; Phase transformations; High strength alloy; Ultrasonic waves; Heterogeneous nucleation; XRD; Solidification; Titanium alloys; Recrystallization; Zirconium alloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.09.046

▶ Cavitation melt treatment applied above the temperature of primary aluminum formation promotes fragmentation of Al 3Zr particles, decreases the size of potential solidification sites, and increases their number. ▶ Ti substitutes Zr in Al 3(Zr 1− x Ti x ) particles, increasing the interfacial energy between aluminum and Al 3(Zr 1− x Ti x ) particles, which leads to the delay of nucleation to larger undercooling. ▶ In this way Ti delays the nucleation to the temperature when smaller Al 3(Zr 1− x Ti x ) particles, previously refined by cavitation, can be activated. In high-strength aluminum alloys Ti and Zr are commonly present as alloying elements, mostly as anti-recrystallization agents. Grain refinement during solidification is also achieved using Ti but in the form of titanium borides. Our previous investigations showed that a combined addition of Zr and Ti enables considerable grain refinement in aluminum alloys upon cavitation treatment, much stronger than that of Zr alone. The role of titanium and ultrasonic processing remained unclear. In this paper we propose a mechanism of the grain refinement that includes structural changes in solidification sites, their refinement and initiation of heterogeneous nucleation at lower undercooling.