Effect of Hf on high-temperature strength and room-temperature ductility of Nb-15W-0.5Si-2B alloy

Mechanical responses of Nb-15W-0.5Si-2B-xHf alloys (x = 0, 5, 10 and 15 mol%) were investigated to probe the balance between room-temperature ductility and high-temperature strength depending on Hf concentration in Nb-based solid solution. It is found that Hf addition considerably improves the high-temperature strength of the Nb-15W-0.5Si-2B alloy without loss of the room-temperature ductility. With a Nb solid-solution dominant microstructure, the Nb-15W-0.5Si-2B-15Hf alloy shows a 0.2% compressive yield strength of as high as 365 MPa even at 1400 °C, while its compressive ductility at room temperature is about 17%.