Al-Mg

Abstract

The equilibrium solid phases of the A1-Mg system are (Fig. 1): (1) the face-centered cubic (A1) solid solution. The maximum solubility of Mg in (A1) is 18.9 at. % at a eutectic temperature of 450 ~ (2) the close-packed hexagonal (Mg) solid solution. The maximum solubility of Al in (Mg) is 11.8 at. % at a eutectic temperature of 437 ~ (3) the fl compound of approximate stoichiometry A13Mg2. fl has a complex fcc structure. At low temperature, fl transforms martensitically to another structure that may be a distortion of the fl structure, but the equilibrium phase relations have not been investigated. (4) the line compound R (often designated e in the literature), of composition 42 at. % Mg. (5) the compound 7, with the aMn structure. At 450 ~ 7 has a maximum composition range of approximately 45 to 60 at. % Mg. The ideal crystal structure has the stoichiometry Al12Mg17 (58.6 at.% Mg). The three-phase equilibria and congruent transformation data are given in Table 1. Previous reviews of the A1-Mg phase diagram include [Hansen, Elliott, Shunk, Mondolfo, 53Eic, and 59Ray]. In 60