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

摘要

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) over bar and (5) over bar rather than following the plane of maximum stress. A fracture toughness of 1.25 MPa m(1/2) has been derived from indentations on a fivefold plane at room temperature.