Synthesis and characterization of NiAl–Al2O3 nanocomposite powder by mechanical alloying

The synthesis and characterization of NiAl–Al2O3 nanocomposite powders containing different amount of Al2O3 (20 and 40 vol.% of Al2O3) was investigated. Al, Ni and NiO subjected to high-energy ball milling in a planetary ball mill. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometery and scanning electron microscopy. The mechanical alloying of NiO and Al powder mixture corresponding to the stiochiometric reaction 3NiO + 5Al resulted in the formation of NiAl–40 vol.% Al2O3 after 0.5 h with rapidly mode. The crystallite size of NiAl and Al2O3 were 35 and 60 nm, respectively. The formation of NiAl–20 vol.% Al2O3 took place after 30 h of milling of NiO–34 wt% Al–41 wt% Ni powder mixture. For this composition exothermic reaction with high rate did not occur during the milling process.