A vibrating frame grinder has been instrumented for evaluating the amplitude and frequency of ball oscillation, as a function of the amplitude of vibration of the frame and of the ball mass. Based on such measurements, it is found that Ni Zr~compounds become fully amorphized provided the specific milling intensity is greater than a temperatureand composition-dependent threshold value. The specific milling intensity is the momentum transferred by the ball to the unit mass of powder per unit time.Below this threshold, a two-phase structure (crystalline+ amorphous) is stabilized; the steady proportion of the amorphous phase increases with the milling intensity and decreases on increasing the milling temperature. The intensity threshold increases with temperature and varies in the opposite direction as the hardness of the starting crystalline compound. The amorphous NiZr phase can be obtained by two distinct routes, either starting from the crystalline compound NiZr, or from a mixture of Ni, OZr7 and NiZrã morphous phases. These routes correspond, respectively, to an increase and a decrease in internal energy

The activation volume ΔV for chemical diffusion in Ag50Au50 alloy has been determined from the pressure dependence of the rate of decrease in amplitude of composition-modulated thin films. Based on resistivity measurements, it is argued that the technique yields the bulk chemical diffusion coefficient, in close agreement with the experimental results. Eight measurements of the diffusion coefficient were made, four as a function of temperature (237–309 °C) at atmospheric pressure and four as a function of pressure (0–0.85 GPa) at constant temperature (269.5 °C). The samples, 2000–3000-Å-thick multilayers of alternating silver and gold, with periods between 72 and 160 Å, were made with a newly built UHV sputter-deposition apparatus. The bulk chemical interdiffusion activation energy (1.5 eV) and activation volume (0.72 Ω) agree with those expected from other interdiffusion and tracer measurements.

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