Fracture toughness and the effects of stress state on fracture of nickel aluminidesThe effects of stress state on the fracture behavior of Ni3Al, Ni3Al + B, and NiAl were determined using either notched or fatigue-precracked bend bars tested to failure at room temperature, in addition to testing specimens in tension under superposed hydrostatic pressure. Although Ni3Al is observed to fail in a macroscopically brittle intergranular manner in tension tests conducted at room temperature, the fracture toughnesses presently obtained on Ni3Al exceeded 20 MPam, and R-curve behavior was exhibited. In situ monitoring of the fracture experiments was utilized to aid in interpreting the source(s) of the high toughness in Ni3Al, while SEM fractography was utilized to determine the operative fracture modes. The superposition by hydrostatic pressure during tensile testing of NiAl specimens was observed to produce increased ductility without changing the fracture mode.
Document ID
19920044798
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Lewandowski, John J. (NASA Lewis Research Center Cleveland, OH, United States)
Michal, Gary M. (NASA Lewis Research Center Cleveland, OH, United States)
Locci, Ivan (NASA Lewis Research Center Cleveland, OH, United States)
Rigney, Joseph D. (Case Western Reserve University Cleveland, OH, United States)