ULTRAMICROHARDNESS MEASUREMENT OF ION-IMPLANTED ALUMINA

The changes of hardness and elastic modulus of alumina induced by 0.4 to 4 MeV B, C, Si and Au implantations at a dose of 1 x 10(16) ions cm (-2) at room temperature and a successive heat treatment (1270 K, 1 h in Ar) were studied by ultramicrohardness measurements with a multiple load-partial unload procedure using a spherical indenter. The overall hardness of alumina increased after ion implantation, although the ou ter most surface layer became softer for some implantations. High ener gy implantation made the surface much harder. The hardening was genera lly unaffected by the annealing, although the softer layer became hard er and the Si implanted surfaces became considerably softer. Elastic m odulus decreased after all implantations. After the annealing, the ela stic modulus of implanted samples increased and it slightly decreased for the unimplanted alumina.