Amorphization of NiZr2 under ball-milling: Validation of the milling intensity

Studies of amorphization of NiZr2 compound have been carried out in a magneto ball-mill capable to operate in two milling mode, depending of the direction of the applied magnetic field. The first mode favours ball impacts and the second one cold rolling. We show that much in the same way as in a vertical frame grinder, the compound reaches a two phase (amorphous plus crystalline) steady structure and that the volume fraction of amorphous phase depends at given milling temperature on the milling intensity. The milling intensity is as defined by Chen [1], the momentum transferred per unit mass of powder per unit time : the higher the milling intensity, the higher the fraction of amorphous phase. However the intensity required to reach a given fraction of amorphous phase in the magneto ball-mill seems to be much lower than in the vertical frame grinder. The rolling mode is found to be more efficient than the impact mode at equivalent milling temperature for promoting amorphization.