Synthesis of nanocrystalline Ni3Al by mechanical alloying and its microstructural characterization

Nanocrystalline Ni3Al intermetallic compound was successfully synthesized by mechanical alloying of the mixed powders of elemental Ni and Al. The phase evolution and microstructural changes of the powders during mechanical alloying were investigated by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometry. It was found that supersaturated Ni(Al) solid solution was formed during the early stage of mechanical alloying process. Upon further milling, Ni(Al) solid solution was transformed into ordered Ni3Al intermetallic nanocrystalline. It is imperative to adopt a long enough ball milling time (120 h in the present work) so as to ensure the complete transformation of Ni(Al) solid solution to Ni3Al intermetallic nanocrystalline and the formation of well ordered Ni3Al nanocrystals composed of fine grains with a size of about 11 nm.