Phase equilibria in the Al-Si-V system

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), DTA (DTA) and electron probe microanal. (EPMA). Ternary phase equil. 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, .tau., with the approx. compn. Al0.6Si1.4V was discovered and the structure was detd. by means of single crystal XRD. DTA was used to identify a total no. of nine invariant ternary reactions yielding a ternary reaction scheme (Scheil diagram) in the investigated compn. 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 compn. limits of the phase Si3V5 were reinvestigated and we found that this phase exhibits a noticeable homogeneity range in contradiction to previous literature reports.