Microstructure and 1000-1400 K mechanical properties of cryomilled NiAl-0.7Zr

An attempt has been made to improve the intermediate temperature strength o f cryomilled NiAl by utilizing third element solid solution or precipitatio n strengthening mechanisms. To this end an NiAl-0.7 (at.%) Zr alloy was cry omilled, densified by hot extrusion, and tested between 1000 and 1400 K. Al though over 3 wt% nitrogen was introduced via cryomilling, mechanical testi ng revealed that the cryomilled NiAl-0.7Zr was significantly weaker than th e base alloy between 1000 and 1200 K. Chemical and microstructural analyses revealed that, in addition to similar to 16 vol% AIN, all the Zr had been converted into ZrN, A thermodynamic analysis of cryomilling indicated that the formation of ZrN could have been anticipated since it is a more stable nitride than AIN. While Zr was an unsatisfactory addition in NiAl, thermody namics also suggest several alloying elements that might lead to good inter mediate temperature strength after cryomilling.