Abstract
ABSTRACTCreep strengths and ductilities of boron-doped nickel aluminides are significantly improved by small additions of hafnium. Since creep failure in these alloys proceeds by growth and coalescence of grain boundary cavities, effects of Hf additions on the compositions of grain boundaries and creep cavity surfaces were examined using Auger electron spectroscopy (AES). In order to facilitate intergranular fracture in the AES analysis chamber, gage sections from creep specimens were hydrogen charged and copper plated. Grain boundaries in crept specimens were not flat, and the grains did not exhibit a normal polyhedral appearance. The overall levels of boron detected on the fracture surfaces of the creep specimens were significantly higher than those from uncrept specimens. Additionally, boron was found to segregate more strongly to the grain boundaries while higher concentrations of residual sulfur and phosphorus were detected on the cavity surfaces in both alloys. These results are discussed in terms of the effects of impurity segregation on high temperature grain boundary cavitation.
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.
