Formation of aluminide phases on electrodeposited nanocrystalline nickel

The formation and growth of aluminide phases during pack cementation of electrodeposited nanocrystalline (NC) nickel were investigated and compared with microcrystalline (MC) nickel. MC and electrodeposited NC samples were aluminized at different temperatures for various durations. The microstructure of aluminized specimens was studied by means of SEM and XRD methods. The results showed that the aluminizing time needed for the onset of formation of aluminide phases on NC samples was shorter than MC specimens at all investigated aluminizing temperatures. The aluminide coating formed on MC samples always consisted of Al3Ni2 single layer, whereas the coating formed on NC nickel was Al3Ni2 single layer or Al3Ni–Al3Ni2 double layers depending on aluminizing time and temperature.