Quarternary and quinary additions to directionally-solidified X-X ₃Si eutectics of chromium and vanadium

An alternative high temperature structural alloy system based on the X-X₃Si eutectic compositions of chromium and vanadium is put forward. These low-density (∼6g/cm³) eutectics have a bcc solid-solution to increase alloy fracture toughness, and a A15 X₃Si as the high temperature load-bearing phase. (1/2Cr,1/2V)-(1/2Cr,1/2V)₃Si was used as the base alloy for further element additions, and is represented by the symbol Cyrillic capital letter E. 10at.% tantalum and aluminium were substituted for vanadium as quaternary and quinary alloy additions. Microstructure, elemental phase partitioning, compression creep and oxidation results will be discussed. Cr-Cr₃Si has a tidy, fine lamellar microstructure. Vanadium coarsens and destabilises the lamellae to a limited extent. Tantalum addition causes two distinct populations of eutectic to form; one population having finer lamellae than the other. Aluminium does not coarsen or destabilise the lamellar microstructure. High temperature compression tests at 1200°C and 1300°C show that Cyrillic capital letter E is stronger than the binary alloys, and of similar strength to the quaternary and quinary alloys.