Mécanismes de déformation relative à l'érosion de cavitation

Deformation mechanism relating to cavitation erosion

Institut de Génie atomique, Ecole polytechnique fédérale de Lausanne

Abstract

Copper single crystals have been exposed to vortex cavitation attack with various erosive aggressivity and the variable exposure time. The progressive displacement of damage and the deformation induced have been examined by scanning and transmission electron microscopy. Hardening inside the plastic zone has been measured by a microhardness technique.

The thickness of the work-hardened layers depends on the cavitation aggressivity and the exposure time. As regards pure copper monocrystals, the deformation extends to a depth of 1.2 mm. The deformation substructure varies along this distance by moving away from the surface. In the first 50 μm, the deformation twinning is the most active mechanism which creates a complex form of micro twin-crystals and with sliding in the next 50-15050 μm. In the wider layers, deformation is carried out by sliding which appears in the MET in the form of dislocation cells whose size increases from 0.5 μm at the beginning to 40-50 μm at the end of the deformed zone.