Nanomechanical Analysis and Fractography of Extruded Mg-Dy-Nd Based Alloy Influenced by Solution Heat Treatment

This study concentrates on nanomechanical analysis and fractography of an extruded Mg-Dy-Nd-Zn-Zr alloy in different microstructures. The focus here lies on the reduced elastic modulus evaluated from nanoindentation and the fracture behavior evaluated by scanning electron microscopy (SEM). The initial hot-extruded condition shows a fine-grained microstructure consisting of lamellar long-period stacking-ordered (LPSO) within the Mg-matrix and blocky LPSO-phases and precipitates. Solution heat treatment causes grain growth and dissolution of the LPSO phases and precipitates, the Mg-matrix becomes enriched by solid solution. Except for the blocky LPSO in the extruded microstructure, where the value is higher, the reduced elastic modulus does not change across the microstructural features. C-ring compression tests in Ringer solution were used to evaluate the fracture behavior, mostly transgranular cleavage facets with some ductile features are present. The amount of sub-cracks forming from the main crack are influenced by the heat treatment time. Blocky LPSO do not show very present on the fracture surface.