Argon pressure significantly affects the residual stress in sputter deposited thin films and coatings. In case of W thin films, high residual stresses on the order of 1-2 GPa are quite common. With the rest of sputtering parameters being equal, argon pressure determines the sign and the value of residual stress.When the amount of stored elastic energy in the film due to the residual stress exceeds the interfacial toughness, fracture normally occurs. Telephone cord buckling delamination blisters are commonly observed in compressed thin films. These mechanically active features form by a loss of adhesion between the film and the substrate due to residual stress relief, and exhibit directional growth under certain conditions. This paper considers telephone cord delamination channels for micro-fluidics applications, as this could to be a valuable, reliable, and inexpensive method of forming open channels.

Fretting damage and geometric stress concentrations are known to affect the fatigue strength of clamped joints. The relative magnitudes of these effects were examined in a series of experiments whose results are interpreted in the light of theoretical stress analysis. When full allowance is made for geometric stress concentrations, it is found that fretting can reduce the fatigue strength of B.S. L65 by a factor of about 3. A mechanism is proposed to explain this phenomenon.

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