POSITRON ANNIHILATION STUDIES OF ICOSAHEDRAL AND DECAGONAL QUASICRYSTALLINE ALLOYS

摘要

Positron lifetime measurements on icosahedral and decagonal quasicrystalline (QC) alloys indicated the presence of vacancy-type defects, whose concentration is three orders of magnitude more than that in crystalline metals at room temperature. These defects exhibited a characteristically low mobility and the QC phase of the alloys studied showed a high degree of stability against prolonged heat treatments and aging. These results are found very significant for developing an adequate structural model for the QC phase.