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 strengthenin g mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) N iAl powder have been cryomilled in liquid nitrogen to introduce AIN particl es at the grain boundaries. As an alternative to cryomilling, one lot of OD S NiAl was also roasted in nitrogen to produce AlN. Both techniques resulte d 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 N-2-roasted ODS NiAl alloys were as strong as cryomilled binary NiA l containing like amounts of AIN. The reason(s) for the relative weakness o f cryomilled ODS NiAl is not certain; however the lack of superior strength in N-2-roasted ODS NiAl is probably due to its relatively large AlN partic les. (C) 2000 Elsevier Science S.A. All rights reserved.