| 1 µm Ni films were deposited on both single crystal and polycrystalline Cu disks by magnetron sputtering. Diffusion at 420 ± 3 °C was performed on the Ni/Cu couples with Ar ion irradiation at the Cu side of samples. Diffusion of samples without irradiation were performed for comparison. The Ni concentration distribution profiles analyzed by glow discharge optical emission spectroscopy (GDOES) revealed an enhanced Ni diffusion in single crystal Cu substrate 1 mm away from the irradiated surface, which can be explained by a mechanism of nonlinear lattice vibration. No diffusion enhancement identified in polycrystalline Cu indicates the experimental observation of grain boundary attenuation on the nonlinear lattice vibration modes. |
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