The stability of WC to ion bombardment

Abstract

The mechanical surface properties of single crystal WC are known to be affected by N (100 keV) ion implantation of 2000 ions/m 2, when surface embrittlement occurs. This is considered to be due to dense formations of dislocations which hinder their movement. The present studies concern the ability of the WC crystal structure to withstand radiation damage and to remain crystalline at high fluence. Irradiations of a monolayer of fine powders of WC (particle sizes less than 5 μ) have been carried out using Si (7 MeV) ions up to 10 ions/nm 2. X-ray diffraction patterns have been observed before and after irradiation; the diffraction peaks are displaced indicating a maximum increase of more than 1.0% in volume of the unit cell, peak widths increase very slightly, and the peak intensities decrease slightly and then remain constant. Assuming the maximum lattice parameter changes are due to an equilibrium between the production and annealing of defects, the saturation density of defects is about 10 22 defects/cm 3. There is no evidence for the formation of a non-crystalline condition.