Surface erosion study of alpha-bombarded molybdenum by scanning electron microscopy

Abstract

The surface morphology of 0–40 MeV alpha-irradiated molybdenum to total doses of about 5.45 × 10¹⁷αcm⁻² and 1.14 × 10¹⁸αcm⁻² have been studied by scanning electron microscopy. Pinhole pits and surface flakes are observed and the formation mechanism for both seems to be the same. The structures show strong dependence on crystal orientation. The flakes are faceted and some of them show fivefold symmetry. The irregular shape of pinhole pits are triangular at higher doses with increase in size and decrease in concentration. At higher doses the surface erosion is high and most of the flakes are masked by sponge-like exfoliations. The size and depth of the pits are inversely proportional and indicate that the formation mechanism for helium bubble blisters and pits is not the same. At high ion energies, the compressive stress created by the lattice defects seems to play an important role in surface erosion.