Solid state synthesis of amorphous and/or nanocrystalline Al₄₀Zr₄₀Si₂₀ alloy by mechanical alloying

Abstract

Mechanical alloying of Al₄₀Zr₄₀Si₂₀0 powder blend has been carried out in a high-energy shaker ball mill up to 50 h. Microstructural evolution at different stages of milling has been characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). During milling, elemental Zr seems to undergo a HCP→FCC polymorphic transformation that is closely related to grain refinement and plastic strain. On the other hand, nanocrystallization and mutual dissolution of the elemental blend lead to partial solid state amorphization and development of a composite microstructure comprising of varying proportion of an amorphous phase and nanocrystalline FCC-Zr based solid solution by appropriate hours of milling. In general, the present results compare well with that from our earlier studies on mechanical alloying of Al₄₀Nb₄₀Si₂₀ and mechanical milling of elemental Zr, respectively.