Mechanical characteristics of melt grown doped KMgF3 crystals

Results of indentation induced hardness testing studies conducted on (1 0 0) cleavages of melt grown KMgF3 crystals doped with 5% NiF2 are reported. Mechanical characteristics including Vickers microhardness, fracture mechanics, crack propagation, brittleness and yield strength of the crystal are assessed. Variation of microhardness with load is non-linear and is best explained by the concept of Newtonian resistance pressure as proposed by Hays and Kendall’s law. Classification of cracks and their transition from Palmqvist to median types is explained. The average values of fracture toughness (Kc), brittleness index (Bi) and yield strength (σy) are calculated using expressions for Palmqvist and median types of cracks.