Amorphous and quasi-crystalline phases in rapidly solidified MgAlZn alloys

The formation of amorphous and icosahedral phases and approximants has been identified in rapidly solidified MgAlZn alloys. The icosahedral phase is located at the composition range between those of the amorphous phase and approximants. Mg 40Al 40Zn 20 is a cubic 1 1 approximant in the equilibrium state and a cubic 5 3 rational approximant in the rapidly solidified state. Rapidly solidified Mg 50Al 30Zn 20 and Mg 50Al 20Zn 30 have a disordered icosahedral structure with a high density of random phason strain. The valence concentration e/ a plays an important role in the selections of rapidly solidified structure between the amorphous and the icosahedral phases and of phason strains between isotropic and anisotropic.