Toughening and strengthening behavior of an Nb–8Si–20Ti–6Hf alloy with addition of Cr

The microstructure, fracture toughness and effect of temperature on the strength of Nb–8Si–20Ti–6Hf–(6,10,14)Cr alloys were studied. Fracture toughness was decreased by addition of Cr. It is interesting that, up to 1150 °C, the hardness or strength was improved by addition of Cr, whereas above that temperature the strength decreased. As the Cr content increased from 6 to 14 at.%, the yield strength σ0.2 increased from 268 to 313 MPa at 1150 °C, but decreased from 125 to 85 MPa at 1350 °C.