The measurement of positron annihilation lifetime of Zr containing Ni3Al showed that the lifetime parameters of positron in Ni3Al(Zr) alloys cooled in air after homogenized at 1150C decreased with an increase of Zr content, which indicated that Zr atoms diffused to grain boundaries and segregated there. When alloys were cooled in water, the lifetime parameters almost kept invariable with the increase of Zr concentration, meaning that Zr atoms could not diffuse to grain boundaries because of the rapid cooling speed, but existed in Ni3Al as solid solution.

Diffusive Behavior of Zr in Ni3Al Measured by Positron Annihilation Technique. Guo, J., Li, Y., Xiong, L.: Nuclear Techniques, 2005, 28[12], 909-12