A nanoindentation study of the effect of crystal-size on shear banding in Mg-based nanophase composites

•Shantanu Madge1, Gerhard Wilde1 und Lindsay Greer2
1Institute of Nanotechnology, Forschungszentrum Karlsruhe, D-76021, Germany.
2Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, U.K.

Nanoindentation has been used to study the efficacy of crystals in obstructing shear band propagation in two nanophase composites obtained by partial devitrification of Mg-based bulk metallic glasses. Pronounced steps are observed in the loading curves for the as-cast glasses, which reflect shear banding in the material. The composition Mg65Cu15Ag10Y10 (at. effective in blocking shear band propagation in the partly crystallized material. On the other hand, the glass Mg66Ni20.4Nd13.6 (at. crystals that are much coarser and consequently, are more effective in blocking shear band propagation. The implications of these results for optimising the mechanical properties of bulk glasses are discussed.