Identification of β phase particles in an isothermally aged Al-10 mass%Mg-0.5 mass% Ag alloy

Abstract

The structure and morphology of coarse-scale globular and smaller spheroidal particles in an isothermally aged Al-10Mg-0.5Ag (mass%) alloy have been charcterised by means of transmission electron microscopy. Coarse-scale globular and smaller spheroidal particles were commonly observed in an over-aged sample aged for 72 h at 240°C. The coarse-scale globular and smaller spheroidal particles were identified by electron microdiffraction to have the face-centered cubic structure of equilibrium β phase (Al 3Mg2) (lattice parameter a = 2.824nm). The orientation relationship between the β phase and α-Al matrix was such that: (100)β // (100)α and [001]β // [001]α. This orientation relationship differs from those reported previously for the β phase formed in binary Al-Mg alloys. The coarse-scale globular β particles had invariably internal faulted structures. © 2005 The Japan Institute of Metals.