The role of Hf and TiC additions in the mechanical properties and microstructure of NbAlV alloys

The microstructures and mechanical properties of Nb-12Al-20V (at.%) containing Hf or TiC have been investigated. The microstructures were characterised using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The NbAlV alloy is single B2 phase, the 5% Hf added completely dissolving into the matrix. The addition of 5% Hf and 5% TiC resulted in the formation of MC-type Hf-rich carbide. Compression testing has been carried out at room temperature, 1273 and 1473 K. The alloys show good compression ductility at room temperature. Hf addition gave a slight increase in strength at both room temperature and high temperature. The addition of both Hf and TiC significantly improves the strength. The room temperature strength of these alloys could be well described by solid solution strengthening and a load transfer mechanism. The alloys deform primarily via dislocation slip, with some mechanical twinning.