Research On Structure And Mechanical Behavior Of Oxygen-doped Disordered Alloys Via Neutron And Synchrotron Radiation X-ray Scattering

After the rapid development in recent decades,disordered alloys（amorphous alloys and high entropy alloys）have shown broad application prospects in precision devices,biomedicine,aerospace and other fields.By using the control of"order"or"entropy",disordered alloys break the traditional design concept of single principal element of crystalline metal materials,and thus obtain unique and excellent mechanical,physical and chemical properties.However,due to the complexity of disordered alloys,the microstructure of amorphous alloys cannot be fully characterized by traditional research methods,which makes it difficult to understand the structure-activity relationship of alloys.In the field of high entropy alloys,the study of mechanical deformation mechanism has become a hot topic.Oxygen is a rich and active element.Almost all elements can react with oxygen.In the actual production and application process,aerobic doping is inevitable.The brittle phase such as oxide dendrites formed by the addition of oxygen is the main reason for the deterioration of the properties of alloy materials.However,recent studies have shown that the microalloying of oxygen can greatly improve the plasticity of disordered alloy materials while increasing the strength.In this paper,the effects of oxygen microalloying on the phase composition and mechanical properties of Ti_42.5Cu₄₀Zr₁₀Ni₅Sn_2.5 high entropy amorphous alloy were investigated.It was found that 0.2 at.%oxygen can effectively improve the strength and plastic deformation capacity of the alloy.The structural origin of the excellent mechanical properties of Ti_42.5Cu₄₀Zr₁₀Ni₅Sn_2.5 high-entropy amorphous alloy caused by oxygen microalloying was further investigated by neutron scattering and synchrotron radiation X-ray advanced characterization techniques to analyse the correlation between microstructure and mechanical properties.Micro-alloying of oxygen elements enhances the ordering of the short range ordering（SRO）of the high-entropy amorphous alloy and increases the proportion of highly symmetrical icosahedral clusters centred on Cu atoms,resulting in excellent strength and toughness.Finally,the micromechanical mechanism of abnormal deformation behavior of oxygen microalloyed Ti Zr Hf Nb high entropy alloy was investigated by in-situ neutron diffraction.The pinning effect of ordered oxygen complexes promote dislocation proliferation and cross-slip,improves work hardening rate,and further improves the strength and plasticity of（Ti Zr Hf Nb）₉₈O₂.At the upper yield point,the{110}oriented grains are the first to undergo lattice strain softening,and at the lower yield point,the lattice strain of the{110}oriented grains increases again,indicating that the{110}oriented slip system continues to slip after the dislocations have passed through the ordered oxygen complexes.Moreover,the diffraction peak intensity and full widths at half maximum of each orientation grain are higher than those of Ti Zr Hf Nb high entropy alloy,which also proves that ordered oxygen complexes promote the multiplication of dislocation.