Study of microindentation cracks in bismuth-doped arsenic selenide glasses

The formation of radial cracks from Vickers indentations on the surfaces of both unirradiated and irradiated samples of (As(1) (-) (x)-Bi(x))(2)Se(3) glasses with x <= 0.1 is investigated as a function of indentation load P. It was found that radial cracks around indentations are produced on the surfaces of all samples at loads exceeding a particular applied load P(c)(app) but this threshold load is higher by a factor of 15 to 30 from the value of P(c) calculated from the theoretical dependence of ratio c/d of crack length c measured from the center of indentation impression to indentation impression diagonal d on applied load P. By fitting the experimental P (c(3/2)) data in an expression relating c and P according to expanding cavity for elastic/plastic solid and from a theoretical expression relating load-independent hardness H and threshold load P(c) for crack formation estimated from the experimental data of the dependence of rid on P. the value of indentation fracture toughness K(C) of As(2)Se(3) glasses, irrespective of Bi content in the samples and their irradiation, was found to be about 0.52 MPa.m(1/2). (C) 2011 Elsevier B.V. All rights reserved.