Annihilation characteristics of positrons in amorphous alloys

The state of positrons in Co73Fe5Si12B10, Cu35Zr65, Cu50Zr50 and Cu65Zr35 amorphous alloys was examined by the precise measurement of positron lifetime and the Doppler broadening of annihilation quanta, and the two-parameter correlation measurement of these quantities. This two-parameter technique is a new method suitable to the study on the state of positrons. The experimental setups were the same as those reported before. The Doppler broadening of annihilation quanta was measured with a Ge(Li) detector. Each mode of positron annihilation can be uniquely defined by both single characteristic lifetime and a single distribution of momenta. The dependence of lifetime on momenta is not due to the mixing of free annihilation, but to the size distribution. The structural relaxation and crystallization proceed in four steps in the isochronal annealing of Co73Fe5Si12B10. The circumstance seen in the positrons in amorphous Cu-Zr alloy resembles that in annealed Zr. (Kako, I.)