Local structure change of Ce and Cu in the course of nanocrystalline formation from amorphous Al₈₇Ni₈Ce₃Cu₂

Local structures of Ni in Al₈₇Ni₁₀Ce₃ and Al₈₅Ni₁₀Ce₅ and Cu in Al₈₇Ni₈Ce₃Cu₂ are studied by means of XAFS measurements in order to know the role of small additives in the formation of nanocrystalline α-Al from amorphous matrix. Local structures of Ni in Al₈₇Ni₁₀Ce₃ and Cu in Al₈₇Ni₈Ce₃Cu₂ show very small changes after annealing just after the α-Al nanocrystalline formation, which indicates both Ni and Cu are excluded from precipitated α-Al like Ce in Al₈₇Ni₁₀Ce₃. Local structure of Cu for the as-quenched state is different from that of Ce and Ni; nearest neighbors of Cu consist of Cu rich atoms, while those for Ce and Ni consists mostly of Al rich. Small amount of Cu addition induces segregation of Cu rich region and increases inhomogeneity of the matrix.