Enhanced mechanical properties of a large-size metallic alloy through a gradient microstructure

The gradient microstructure and deformation mechanisms of an as-cast 6 mm-diameter ZrCuAl metallic alloy are investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The metallic alloy with gradient microstructure in both phase constituent and grain size from surface to core is prepared based on a fast cooling technique. The quasi-static mechanical property of the alloy is studied and it is found that a good combination of strength-ductility, as well as low Young's modulus and high fracture strength of the alloy are achieved due to the suppression of the strain localization. Combined study of SEM and TEM on deformation mechanisms shows that the gradient microstructure with martensitic transformations, twinnings and dislocations contributes to the enhanced mechanical properties of the large-size metallic alloy.