Positron annihilation characterization of Fe-Y2O3 composite powder after mechanical alloying and heat treatment.
Fe-1 wt% Y2O3 composite powders were mechanically alloyed for 12 hr and then heat-treated at 1050 degrees C for 1 hr. Positron annihilation lifetime and coincidence Doppler broadening measurements are in qualitative agreement with X-ray diffraction studies, indicating that in the as-mixed Fe-1Y2O3 composite, up to approximately equal to 70% of the annihilations occur at vacancy clusters; a small fraction annihilates in its matrix. In the case of mechanically alloyed composite, up to approximately equal to 60% of the positrons annihilate at vacancy clusters. Some annihilations also occur in dislocations. In the heat-treated Fe-1Y2O3, positrons primarily annihilate at yttria precipitates, while a small fraction annihilates in the matrix.
Sheet Products and Process Research Group, POSCO Technical Research Laboratories, Jeonnam, 545090, Korea.
Jae Hoon
JH
Lee