Measuring the Brittle-to-Ductile Transition Temperature of Tungsten-Tantalum Alloy Using Chevron-Notched Micro-Cantilevers

High-temperature micro-fracture tests of an industrial grade W-1%Ta alloy were performed from room temperature up to 700 °C, using chevron-notched micro-cantilevers. A gradual increase of conditional fracture toughness (KQc) was measured with increasing temperature, and a microscale brittle-to-ductile transition temperature was found at ~600 °C. This is slightly higher than macroscopic four-point bending tests from the same material (~400 °C), and contradicts most literatures for pure tungsten that shows a significant lower micro-BDTT. The results suggested that dislocation motion should be independent of the specimen size. It is concluded that the higher micro-BDTT is due to tantalum in this alloy.