RELATIONSHIP BETWEEN ICOSAHEDRAL AND MONOCLINIC PHASES IN AL-CU-FE ALLOY

The orientational relationship between the icosahedral (I) phase and the monoclinic phase in Al-Cu-Fe alloy has been studied by electron diffraction. The monoclinic phase is isomorphic with Al13Fe4and is called the λ2phase. It has been found that the transformation from the I phase to the λ2 phase can be described by combining a rotation of the physical space and a rotation of the projection strip which is equivalent to a special linear phason strain. The proposed linear phason strain can also be used to describe the transformation from the decagonal phase to the crystalline phase isomorphic to Al13Fe4in other alloy systems. It is pointed out that the structure of the I phase might be related to some extent to the structure of the λ2phase. © 1990 Taylor & Francis Group, LLC.