Identification of beta Phase Particles in an Isothermally Aged Al-10 mass percent Mg-0.5 mass percent Ag Alloy

摘要

The structure and morphology of coarse-scale globular and smaller spheroidal particles in an isothermally aged Al-10Mg-0.5Ag (mass percent) 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 deg C. The coarse-scale globular and smaller spheroidal particles were identified by electron microdiffraction to have the face-centered cubic structure of equilibrium beta phase (Al_3Mg_2) (lattice parameter a = 2.824nm). The orientation relationship between the j3 phase and alpha-Al matrix was such that: (100),, // (100),, and [001]_(beta) // [001]_(alpha). This orientation relationship differs from those reported previously for the beta phase formed in binary Al-Mg alloys. The coarse-scale globular [i particles had invariably internal faulted structures.