Effects of B and Si on the fracture toughness of the Nb-Si alloys

Nb-Si alloys have been widely considered as the potential candidate materials for turbine applications. Optimal amounts of B and Si addition to Nb-18Ti-14Si (at%, F1) were identified based on Nb-Ti-Si-B phase diagram. Nb-18Ti-14Si-4.5B (F2) had been obtained desirable (Nb) + T2 eutectic and significantly improved fracture toughness from 7.85 (F1) to 11.98 MPa m1/2. With extra 3Si addition, F3 (Nb-18Ti-17Si-4.5B) consisted of primary T2 and (Nb) + T2 eutectic, it retained comparable fracture toughness of 11.76 MPa m1/2, even excessive amounts of primary T2 do not compromise fracture toughness.