Microstructure and mechanical properties of electron beam weld joints of a Zr₄₁Ti₁₄Cu₁₂Ni₁₀Be₂₃ bulk metallic glass with Zr

Abstract

The electron beam welding technique was used to join Zr₄₁Ti₁₄Cu₁₂Ni₁₀Be₂₃ bulk metallic glass (BMG) to crystalline pure Zr. Compositional, microstructural, and mechanical property variations across the welded interface were evaluated. It is shown that a crystalline layer develops close to the welding interface. Transmission electron microscopy of this layer indicates the crystalline phase to be tetragonal with lattice parameters close to that reported for Zr₂Ni. However, the composition of this phase is different as it contains other alloying additions. The interface layer close to the bulk metallic glass side contains nanocrystalline Zr₂Cu phase embedded in the glassy matrix. Nanoindentation experiments indicate that the hardness of the crystalline layer, although less than the bulk metallic glass, is more than the Zr itself. Commensurately, tensile tests indicate that the failure of the welded samples occurs at the Zr side rather than at the weld joint.