Microstructure and strengthening of creep-tested cryomilled NiAl-AlN
- AYT, Cleveland, OH (United States)
- NASA Lewis Research Center, Cleveland, OH (United States)
- Exxon Research and Engineering Co., East Annandale, NJ (United States)
The B2 intermetallic NiAl is considered to be a prime candidate material for use as very high temperature structural components in gas turbine engines. The mechanical grinding of prealloyed NiAl powder in liquid nitrogen (cryomilling) results in an intermetallic matrix composite where micron sized particle free aluminide cores (grains) are surrounded by thin mantles comprised of nanometer sized AlN particles and NiAl grains. Under high temperature, slow strain rate conditions both compressive and tensile creep testing have shown that the mechanical strength of hot extruded cryomilled NiAl approaches the levels exhibited by advanced NiAl-based single crystals and simple Ni-based superalloys. Transmission electron microscopy of cryomilled materials tested between 1,100 and 1,300 K revealed little, if any, dislocation structure within the mantle regions, while the NiAl cores contained subgrains and dislocation networks after testing at all strain rates between 10{sup {minus}4} and 10{sup {minus}8} s{sup {minus}1}. These and other microstructural observations suggest that creep strength is the result of a fine NiAl grain/subgrain size, the inability of dislocations to move through the mantle and stabilization of the microstructure by the AlN particles.
- OSTI ID:
- 571807
- Report Number(s):
- CONF-961202--
- Country of Publication:
- United States
- Language:
- English
Similar Records
NiAl-base composite containing high volume fraction of AlN particulate for advanced engines
Elevated temperature compressive properties of N-doped NiAl