Deformation and Cracking in Ge–Sb–Se Chalcogenide Glasses During Indentation.

Deformation and cracking behavior of Ge–Sb–Se binary and ternary chalcogenide glasses of varying average covalent coordination number, 〈 r〉, was studied by indenting with Vickers and Brinell microindenters using static and recording machines, and subsequent analysis using a non-contact profilometer. Vickers-produced cracks were the smallest around the GeSe4 composition (〈 r〉=2.4) after unloading, hence the indentation toughness was a maximum and the brittleness a minimum at 〈 r〉=2.4. Brinell-created pond (crater) depth, the mound (pile-up) height, and the radial fractures originating from the mounds displayed minima in the binaries, presumably due to maximized elastic recovery around 〈 r〉=2.4. Consequently, Brinell hardness computed from the unloaded depth ( HBD) showed a maximum around GeSe4. The maximized elastic recovery around GeSe4 is consistent with Phillips' optimized connectivity arguments. GeSe4 resembles the “anomalous” SiO2 glass for deformation and cracking behavior. Surprisingly, many of the extrema were nearly non-existent in the ternary glasses. The apparent contrast to the binary glasses is not understood. [ABSTRACT FROM AUTHOR]