Abstract: Many compressive and tensile tests showed that the room temperature ductility of boron-free Ni_3Al alloy may be markedly improved by a moderate addition of Zr.The ductility of the stoichiometric Ni_3Al and even slightly enriched with Al,may be improved fairly between 400 —600℃,which behaves much better if Zr is added together with B.However,the high tem- perature ductility of Ni_3Al alloys containing Cr may be significantly increased by Zr which segregates slightly along grain boundaries.Thus,the toughening mechanism of Zr alloying seems to be different from that of B addition.

Key words: Ni_3Al, Zr, toughening, ductility, brittleness