Structure and properties of rapidly solidified Al-Zr-Ti alloys

The Al-Zr-Ti system has recently been suggested as a candidate for Al-based materials capable of retaining a high strength during a long term exposure to high temperatures up to 700 K. The Al-1.25 at.% (Zr+Ti) alloys with a v ariable Zr : Ti ratio were rapidly solidified using the melt spinning metho d. The solidification structure was found inhomogeneous along the direction perpendicular to the ribbon plane and dependent on the Zr : Ti ratio. The microhardness values were correlated with the structure and chemical compos ition. The presence of second phase particles in the as melt-spun ribbons w as proved by SAXS experiments. X-ray and electron diffraction experiments e nabled to identify most of particles as the metastable Al-3(ZrxTi1-x) phase with the cubic L1(2) structure. Especially in the Zr-rich alloys, these pa rticles precipitated preferentially in a fan-shaped morphology. The grains of the Ti-rich alloys were nearly free of these particles. (C) 2000 Kluwer Academic Publishers.