THE REVERSIBLE CRYSTAL-QUASI-CRYSTAL TRANSITIONS IN ICOSAHEDRAL AL-CU-FE ALLOYS

A perfect icosahedral phase, which shows narrow diffraction peaks, exists in Al-Cu-Fe alloys only within a restricted temperature range, between 1020 K and 1120 K. It undergoes two types of reversible transitions. Above the upper temperature limit, the icosahedral phase transforms to a mixture of crystalline phases and residual liquid by a peritectic reaction. Below the lower-temperature limit, it turns into a closely related rhombohedral modification through a solid state transition. The two types of reactions were studied in detail by powder neutron diffraction techniques the results of which are reported on. These results are complemented by electron microscopy data. © 1991, Taylor & Francis Group. All rights reserved.