INDENTATION FRACTURE IN THE IN1-XGAXASYP1-Y/INP SYSTEM AND ITS EFFECT ON MICROHARDNESS ANISOTROPY CHARACTERISTICS

Knoop microhardness anisotropy measurements on the In//1// minus //xGa//xAs//yP//1// minus //y/InP system have disclosed an appreciable variation in hardness behaviour across the composition range of the alloy. This paper relates these variations to changes in the directional fracture characteristics of the system. The qualitative investigation of both Vickers and Knoop indentation fracture has established the emergence of a secondary less than 100 greater than cleavage direction at high values of the composition parameter. The marked change in Knoop microhardness anisotropy characteristics with increasing y in the In//1// minus //xGa//xAs//yP//1// minus //y/InP system has been partially correlated to the emergence of less than 100 greater than cleavage and the general increase in indentation fracture, highlighted by the quantitative fracture measurements. Thus, it is concluded that even at very low indentation loads, the effect of fracture on the measured hardness of crystalline materials cannot be ignored.