CHARACTERIZATION OF NANOCRYSTALLINE NI33ZR67 ALLOY

Nanocrystalline samples with grains in the range of 12-94 nm were synt hesized via thermal crystallization of the amorphous alloy. High-resol ution electron microscope observations show that the nanocrystalline N i33Zr67 Sample is composed of many ''orientation regions.'' Each orien tation region consists of a high density of well-defined microtwin dom ains: Positron annihilation spectroscopy reveals that two types of def ects are present in the Ni33Zr67 samples. With the increase of anneali ng temperature up to 973 K, the two types of defects show remarkable c hange while microhardness changes slightly. The contributions of the m icrotwin domain and the nature of constituent phases to microhardness in the present alloy system are discussed. (C) 1997 American Institute of Physics.