Phase equilibria in the Al–Si–V system

Abstract

The ternary Al–Si–V phase diagram between 0 and 50 at% V was investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Ternary phase equilibria were investigated within three isothermal sections at 500 °C and 620 °C for alloys up to 20 at% V and at 850 °C for alloys with more than 20 at% V. A new ternary phase, τ, with the approximate composition Al 0.6Si 1.4V was discovered and the structure was determined by means of single crystal XRD. DTA was used to identify a total number of nine invariant ternary reactions yielding a ternary reaction scheme (Scheil diagram) in the investigated composition range. A partial liquidus surface projection was constructed by combining our own DTA data with literature data for the limiting binary systems. In the binary Si–V system, the composition limits of the phase Si 3V 5 were reinvestigated and we found that this phase exhibits a noticeable homogeneity range in contradiction to previous literature reports.