On the orientation dependence of crack-like failure formation near indentations on an icosahedral Al-Pd-Mn quasicrystal

Abstract

Crack propagation near microhardness indentations on surfaces of an icosahedral Al₇₀Pd₂₃Mn₇ single quasicrystal exhibiting fivefold and twofold symmetry has been studied under ambient conditions at room temperature using optical microscopy, atomic force microscopy and laser scan microscopy. Cracks exhibit a shear-like habit and prefer propagation along planes of symmetry 2, 3 and 5 rather than following the plane of maximum stress. A fracture toughness of 1.25 MPam^½ has been derived from indentations on a fivefold plane at room temperature.