The structure and decomposition of Al-Cu alloys rapidly quenched from the liquid state.

Al-0.5 to 4mass%Ce, Al-1 mass%Fe-0.5mass%Ce and Al-4mass%Fe-4mass%Ce alloys were rapidly solidified into a ribbon shape at 105 and 106K/s by a single roller technique. The solid solubility of Ce in aluminum cooled at 106K/s extends up to about 0.5mass%. A spherical metastable phase which probably has f.c.c. structure a=0.828nm is observed in the ribbons containing Ce 1 to 4mass%. Coarse spherical particles and cell structures form at a cooling rate about 105K/s. The spherical particles and cell boundary intermetallic compounds have an orthorhombic structure with a stoichiometry corresponding to the equilibrium Al4Ce phase. Al-4mass%Fe-4mass%Ce alloys solidified at 106K/s contain fine particles of Al-Ce metastable phase. When these alloys and the alloy containing supersaturated solid solution are heated at 673K for 3.6ks, a plate shaped Al-Fe-Ce metastable phase precipitates in the direction of the matrix. This phase probably has a cubic structure with an unit cell parameter a=0.410nm. Al-Fe-Ce metastable phase precipitated in the α-cell and the cell boundary intermetallic compound in the alloy cooled at 105K/s have a tetragonal structure with a stoichiometry corresponding to the equilibrium Al8CeFe4 phase.