Abstract
The alloying effects of Ta and W on the phase composition, microstructure and room-temperature fracture toughness of Nb-Si based alloys were investigated. The nominal compositions of Nb-Si based alloys were Nb-15Si-24Ti-4Cr-2Al-2Hf (base alloy, at.%), Nb-15Si-24Ti-4Cr-2Al-2Hf-1Ta (1Ta alloy, at.%) and Nb-15Si-24Ti-4Cr-2Al-2Hf-1W (1W alloy, at.%). Results showed that the base alloy, 1Ta alloy and 1W alloy were composed of Nb solid solution (Nbss), αNb5Si3 and small volumes of hexagonal γNb5Si3 phases. The elements of Ta and W were primarily partitioned in the Nbss phases. The addition of Ta improved the fracture toughness of the base alloy from 10.2 to 12.2 MPa m1/2, but the addition of W reduced the fracture toughness to 8.2 MPa m1/2. The fracture of Nbss phases in the three alloys exhibited a cleavage fracture mode, and river patterns were created on individual facets, while the Nb5Si3 phases showed a brittle fracture mode with flat and featureless fracture surfaces. Different with base alloy and 1W alloy, 1Ta alloy involved the occurrence of secondary cracking as well as interface decohesion. The toughening mechanisms of Nb-Si based alloys with Ta and W additions were emphasized.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
