Formation of the metastable phase upon crystallization of light amorphous Mg-Ni-Y alloys

The decomposition of the amorphous phase upon heating of the Mg87Ni13 and Mg83Ni13Y4 amorphous alloys prepared by rapid quenching of the melt is investigated. The nanocrystalline structure is formed at the first crystallization stage and contains crystals of magnesium and the metastable phase. The structure of the metastable phase (the lattice parameters and space group) is determined. The possible chemical compositions of the metastable phase are considered. No differences are revealed in the structures of the metastable phases in the yttrium-containing and yttrium-free alloys. Heating of the alloys results in decomposition of the metastable phase. After completion of the transformations, the alloy structure consists of Mg and Mg2Ni in accordance with the equilibrium phase diagram. (C) 2002 MAIK "Nauka/Interperiodica".