Abstract
Interdiffusion in amorphous AlxZr1−x compositionally modulated multilayers was investigated by Auger electron spectroscopy sputter-depth profiling. Microstructural characterisation was performed by X-ray diffraction and cross-sectional transmission electron microscopy. The temperature-dependent chemical diffusion coefficient could be deduced at a series of temperatures in the range of 356 °C to 415 °C and was found to be weakly dependent on composition. The activation enthalpy for the chemical diffusion coefficients is slightly smaller at the composition of the Al-rich am-Al0.62Zr0.38 sublayer (1.6 eV) than at the composition of the Zr-rich am-Al0.27Zr0.73 sublayer (1.8 eV), which is not related to the concentration dependence of the excess free volume but to the smaller atomic size and mass of Al as compared to Zr. The smaller activation enthalpy for interdiffusion in partially crystallised specimens than in entirely amorphous AlxZr1−x multilayers is ascribed to the relatively large excess free volume in the grain boundaries of the nanocrystalline sublayers, as compared to the amorphous phase, at large Al concentrations. On the basis of an evaluation of the role of diffusion-induced stress in amorphous systems, it is shown that stresses induced by interdiffusion relax relatively fast by viscous flow and do not affect the determined diffusion coefficients.
Highlights
Metallic glasses are used in many technological applications due to specific improved properties as compared to the corresponding crystalline phase(s).1,2 These applications range from protective coatings against corrosion3 over catalysis4 to spin valves.5 In order to prepare amorphous materials, the formation of the thermodynamically stable crystalline phase6 has to be suppressed
Interdiffusion in amorphous AlxZr1Àx compositionally modulated multilayers was investigated by Auger electron spectroscopy sputter-depth profiling
The activation enthalpy for the chemical diffusion coefficients is slightly smaller at the composition of the Al-rich am-Al0:62Zr0:38 sublayer (1.6 eV) than at the composition of the Zr-rich am-Al0:27Zr0:73 sublayer (1.8 eV), which is not related to the concentration dependence of the excess free volume but to the smaller atomic size and mass of Al as compared to Zr
Summary
Metallic glasses are used in many technological applications due to specific improved properties as compared to the corresponding crystalline phase(s). These applications range from protective coatings against corrosion over catalysis to spin valves. In order to prepare amorphous materials, the formation of the (in the bulk) thermodynamically stable crystalline phase has to be suppressed. Metallic glasses are used in many technological applications due to specific improved properties as compared to the corresponding crystalline phase(s).. Metallic glasses are used in many technological applications due to specific improved properties as compared to the corresponding crystalline phase(s).1,2 These applications range from protective coatings against corrosion over catalysis to spin valves.. In order to prepare amorphous materials, the formation of the (in the bulk) thermodynamically stable crystalline phase has to be suppressed. This can be achieved by fast quenching of the melt or physical vapour deposition, e.g., by sputter deposition.. Several factors determine the glass forming ability, such as the enthalpy of mixing, size difference of the elemental components, energies of the interfaces between the amorphous and crystalline phases as well as long range diffusivity.. Several factors determine the glass forming ability, such as the enthalpy of mixing, size difference of the elemental components, energies of the interfaces between the amorphous and crystalline phases as well as long range diffusivity. in order, to understand and control the high glass forming ability and resistance against crystallisation of these metallic glasses, as well as the oxidation and corrosion resistance, knowledge about interdiffusion is essential, for the design of new (bulk) metallic glasses with even higher glass forming ability
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
