Investigation into the Possibility of Fabricating Boraluminum Rolling of Increased Strength without Homogenization and Quenching

• Published in: Russian journal of non-ferrous metals 2018-07, Vol.59 (4), p.412-418
• Main Authors: Chervyakova, K. Yu, Belov, N. A., Samoshina, M. E., Yakovlev, A. A.
• Format: Article
• Language: English
• Subjects: Alloy systems; Alloys; Aluminum alloys; Aluminum base alloys; Borides; Chemistry and Materials Science; Copper; Deformation; Dispersions; Electric induction furnaces; Heat treatment; Manganese; Manufacturability; Materials Science; Metallic Materials; Metallurgy; Molds; Particle size distribution; Physical Metallurgy and Heat Treatment; Quenching; Scanning electron microscopy; Smelting; Solid solutions; Solution strengthening; Strength; X ray spectra; Zirconium base alloys
• ISSN: 1067-8212; 1934-970X
• DOI: 10.3103/S1067821218040041

Aluminum alloys of the Al–Cu–Mn (Zr) system possess high strength and manufacturability without heat treatment (HT). In order to investigate the possibility of fabricating an aluminum boron-containing alloy in the form of sheet rolling with increased strength without the HT, Al–2% Cu–1.5% Mn–2% B and Al–2% Cu–1.5% Mn–0.4% Zr–2% B alloys are prepared. To exclude the deposition of refractory boride particles, smelting is performed in a RELTEK induction furnace providing intense melt stirring. The smelting temperature is 950–1000°C. Pouring is performed into 40 × 120 × 200 mm graphite molds. It is established using computational methods (Thermo-Calc) that manganese forms complex borides with aluminum and zirconium at the smelting temperature and a sufficient amount of manganese remains in liquid, while zirconium is almost absent in it. The formation of AlB 2 Mn 2 complex boride is proved experimentally (scanning electron microscopy and micro X-ray spectral analysis), but the amount of manganese remaining in the solid solution is sufficient to form particles of the Al 20 Cu 2 Mn 3 phase in an amount reaching 7 wt %. Boron in the zirconium-containing alloy stimulates the isolation of primary crystals Al 3 Zr, in connection with which an insufficient amount of zirconium remains in the aluminum solid solution for strengthening. The possibility of fabricating thin-sheet rolling smaller than 0.3 mm in thickness with uniformly distributed agglomerations of the boride phase with a particle size smaller than 10 µm is shown. A high level of strength (up to 543 MPa) is attained with no use of quenching or aging due to the isolation of dispersoids of the Al 20 Cu 2 Mn 3 phase during hot deformation ( t = 450°C).