Intergranular fracture tendency in NiAl doped with boron and carbon
- Oak Ridge National Lab., TN (United States)
Near-stoichiometric NiAl alloys produced by powder metallurgy, or by conventional casting and fabrication, exhibit mainly intergranular fracture at ambient temperatures. NiAl doped with 300 wt ppm C also shows grain boundary fracture at room temperature, whereas NiAl doped with 300 wt ppm B exhibits mainly transgranular fracture. George and Liu concluded that boron segregation increases grain boundary cohesion and suppresses intergranular fracture in near-stoichiometric NiAl. In addition to suppressing intergranular fracture, boron additions dramatically increase the yield strength and reduce plastic deformation in NiAl at room temperature. The purpose of this study is to further examine these two factors, i.e., enhancement of grain boundary cohesion and reduction of strain incompatibility, by compression tests of near-stoichiometric NiAl alloys doped separately with 300 wt ppm B and C at room temperature. These alloys were chosen because both carbon and boron increase strength significantly, but only boron suppresses grain boundary fracture. Compression tests were used in this study to obtain plastic deformation beyond yielding and thus ensure strain incompatibility at the grain-boundary region. The results obtained so far provide additional evidence that grain boundaries in NiAl are relatively weak and that boron segregation increases grain boundary cohesion in NiAl.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5454319
- Journal Information:
- Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 30:4; ISSN SCRMEX; ISSN 0956-716X
- Country of Publication:
- United States
- Language:
- English
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