Elevated temperature compressive strength properties of oxide dispersion strengthened NiAl after cryomilling and roasting in nitrogen

In an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) NiAl powder have been cryomilled in liquid nitrogen to introduce AlN particles at the grain boundaries. As an alternative to cryomilling, one lot of ODS NiAl was also roasted in nitrogen to produce AlN. Both techniques resulted in hot extruded AlN-strengthened ODS NiAl alloys which were stronger than the base ODS NiAl between 1200 and 1400 K. However neither the cryomilled nor the N2-roasted ODS NiAl alloys were as strong as cryomilled binary NiAl containing like amounts of AlN. The reason(s) for the relative weakness of cryomilled ODS NiAl is not certain; however the lack of superior strength in N2-roasted ODS NiAl is probably due to its relatively large AlN particles.