Thermodynamic re-modelling of the Cu–Nb–Sn system: Integrating the nausite phase

Lachmann, Jonas; Kriegel, Mario J.; Leineweber, Andreas; Shang, Shun‐Li; Liu, Zhe

doi:10.1016/j.calphad.2022.102409

Cited by 5 publications

(1 citation statement)

References 42 publications

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“…The Cu cross-sectional areas were measured on the transverse crosssectional images taken by a SEM (SU-70, Hitachi), using image analysis software (ImageJ, Wayne Rasband). The Sn atomic composition was chosen to be 25% because of preventing Nb 6 Sn 5 development in case of the Sn composition over 25% in the diffusion reaction stage between Cu-Sn and Nballoy [24,25]. Reportedly, Nb 6 Sn 5 decomposes into coarse Nb 3 Sn grains with less intergranular connections [26,27], which would be a source of uncertainty in the analysis.…”

Section: Nb 3 Sn Specimen Preparationmentioning

confidence: 99%

In-depth S/TEM observation of Ti–Hf and Ta–Hf-doped Nb₃Sn layers

Banno,

Moronaga,

Hara

et al. 2024

Supercond. Sci. Technol.

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In superconducting Nb3Sn layers with coherence lengths of approximately 3 nm, grain boundaries act as effective pinning sites. Thus, grain refinement is an essential issue that directly affects the superconducting critical characteristics of the Nb3Sn layer. In recent years, Hf addition to Nb3Sn wires co-doped with Ta has attracted notable interest as a method that enables grain refinement down to several tens of nm. In-depth characterization of the Nb3Sn grain morphology in Hf-doping is crucially important to correlate the microstructure with the flux pinning characteristics. In this article, the grain morphologies of Ti–Hf and Ta–Hf-doped Nb3Sn layers were clarified by scanning transmission electron microscopy (STEM) and TEM-based automated crystal orientation mapping (ACOM-TEM). STEM/energy dispersive X-ray spectroscopy (EDS) revealed no significant oxide precipitates in our samples. The grain size distribution was attained by ACOM-TEM. Although Hf-doping attained a grain refinement effect in the Nb3Sn layer in both doping cases, the degree of this effect was relatively small for Ti–Hf. Kernel average misorientation (KAM) analysis by scanning electron microscopy-electron backscatter diffraction (SEM-EBSD) unveiled no appreciable difference between the internal strain states of the Nb-alloy parent phases in Ti–Hf and Ta–Hf. One remarkable new finding through STEM/EDS was the presence of a Cu–Hf compound phase in the Nb3Sn layer. The Cu–Hf compound sounds analogous to the Cu–Ti compounds that form when Nb–47Ti with Cu matrix is heat treated. The STEM/EDS maps revealed a larger amount of Cu flow from the Cu-Sn side along the grain boundaries. The large Cu deposition on the grain boundaries might facilitate grain growth in Nb3Sn. Those findings make a novel contribution to the literature as they provide a deep insight into Nb3Sn phase formation via Hf doping.

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Section: Nb 3 Sn Specimen Preparationmentioning

confidence: 99%

In-depth S/TEM observation of Ti–Hf and Ta–Hf-doped Nb₃Sn layers

Banno,

Moronaga,

Hara

et al. 2024

Supercond. Sci. Technol.

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The Cu–Sn System: A Comprehensive Review of the Crystal Structures of its Stable and Metastable Phases

Leineweber

2023

J. Phase Equilib. Diffus.

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The present works assesses the knowledge concerning the crystal structures of phases in the Cu–Sn system having their high relevance due to their occurrence in bronze alloys and soldered systems. The crystal structures of the terminal solid solution phases α-Cu and β-Sn and of the stable main intermediate phases β, γ, ε-Cu3Sn, δ-Cu41Sn11, ζ-Cu10Sn3, η-Cu6Sn5 and η′-Cu6Sn5 and some metastable phases appear to be well established in the literature, but details can be intriguing. This paper attempts to review apparently or truly contradictory structure models derived from experimental diffraction data for the different phases, revealing limiting knowledge in some cases. These results are also analyzed regarding the results of first-principles calculations making use of various model structures. The review is also used to highlight exemplarily problems, which can be experienced upon widespread, “routine” means of phase identification, in particular x-ray diffraction (on polycrystalline specimens) and electron backscatter diffraction.

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