INVESTIGATIONS ON INDENTATION INDUCED HARDNESS AND FRACTURE MECHANISMIN FLUX-GROWN DYALO3 CRYSTALS

Results of Vickers' microhardness (H-v), fracture toughness (K-c), bri ttleness index (B-i) of (110) and (001) faces of flux grown dysprosium aluminate crystals, in the load range of 10-100 g are given. The vari ation of microhardness with load is found to be non-linear and is expl ained by using Hays and Kendall's law. Applicability of Hays and Kenda ll's law gives us the load independent values of hardness. Hardness an isotropies for both the crystal planes are reported. The cracks are cl assified into Palmqvist and Median types. There is a transition from P almqvist to Median types of cracks at higher loads. The values of frac ture toughness (K-c), brittleness index (B-i) and yield strength (sigm a(y)) are calculated using median type of cracks. (C) 1998 Elsevier Sc ience B.V. All rights reserved.