Effect of Ni addition on formation of amorphous and nanocrystalline phase during mechanical alloying of Al-25 at.%Fe-(5,10) at.%Ni powders

Al-Fe-Ni ternary powder mixtures containing 25 at.%Fe-5 at.%Ni and 25 at.%Fe-10 at.%Ni were mechanically alloyed by a high-energy planetary ball mill. Structural evolution of these powders during milling was investigated by X-ray diffraction technique and transmission electron microscopy. Almost complete amorphous phase in Al70Fe25Ni5 system is observed at the early milling stage. The amorphous phase transforms into metallic compound Al-5(Fe,Ni)(2) and then the compound changes to ordered AI(Fe,Ni) phase. The last milling products in Al70Fe25Ni5 system are amorphous phase plus nanocrystalline of the disordered AI(Fe,Ni) phase changed from the ordered AI(Fe,Ni) phase. During milling of Al65Fe25Ni10 system, alpha-Al and alpha-Fe solid solutions formed at the early stage change to the ordered AI(Fe,Ni) compound and at last the ordered phase changes to the disordered AI(Fe,Ni) phase. Ten percent of Ni addition promotes retardation of the formation of the amorphous phase. (C) 2002 Elsevier Science Ltd. All rights reserved.