A transmission electron microscope study of hardness indentations in MoSi2

Transmission electron microscopy and electron diffraction were used to study hardness indentations made at room temperature in ⟨001⟩-oriented single crystals of MoSi2. Two families of slip systems, {110}⟨001⟩ and {101}⟨010⟩, were identified. The first system formed ⟨001⟩ dislocation loops by prismatic punching beneath the indenter, while the second system led to large rotations of the crystal lattice beneath the indenter. The lattice rotations were used to estimate the density of dislocations stored in this volume. The results demonstrate that the hardness response of MoSi2 can be explained by the expanding cavity model with most of the plastic accommodation occurring immediately beneath the indenter.