The precipitation behaviour of a hexagonal two-dimensional aperiodic phase in Al-rich Al-Mn-Be alloy has been investigated. Upon heat treatment at temperatures above 450°C, the icosahedral phase formed in a conventionally cast Al-2.5at.% Mn-3at.% Be alloy transforms into the stable hexagonal HI phase. The solute partitioning during transformation leads to the precipitation of a hexagonal two-dimensional aperiodic approximant phase (H′ phase). The precipitates have an orientation relationship with the α-Al matrix. The similarity of the diffraction features indicates that the hexagonal two-dimensional aperiodic structure of the H′ phase is an intermediate structure between the true sixfold quasiperiodic structure and the hexagonal structure of the crystalline counterpart H1 phase.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics