Influence of oxygen impurity on containerless solidification of quasicrystalline-forming Zr80Pt20 alloy

ABSTRACTThe influence of oxygen content on containerless solidification of Zr80Pt20 alloy has been studied by using conical nozzle levitation (CNL) technique. The doping level of oxygen from 41 to 5450 ppm mass oxygen (PMO) affects the undercooling of the liquid Zr80Pt20 alloy. Time-resolved synchrotron x-ray diffraction revealed that the quasicrystalline (QC) phase precipitated as a primary phase during solidification of the Zr80Pt20 alloy. The amount of the QC phase depends on the oxygen content in the alloy. This indicates that the doping level of oxygen in Zr80Pt20 alloy can be related to the metastable phase formation as well as the glass-formation ability.

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Time-Resolved X-Ray Diffraction Study on Solidification of Fe-B and Fe-C Eutectic Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.1702 ◽

2012 ◽

Vol 706-709 ◽

pp. 1702-1706 ◽

Cited By ~ 6

Author(s):

Akitoshi Mizuno ◽

Jin Tamura ◽

Shinji Kohara ◽

Masahito Watanabe

Keyword(s):

Cooling Rate ◽

Crystalline Phase ◽

Metastable Phase ◽

Transformation Process ◽

Undercooled Liquid ◽

Eutectic Alloys ◽

X Ray Diffraction ◽

Structural Variations ◽

Time Resolved ◽

X Ray

Solidification processes of Fe-B and Fe-C eutectic alloys have been investigated by a time-resolved synchrotron x-ray diffraction under containerless cooling conditions using a conical nozzle levitation technique. To observe relative variations of structure from the undercooled liquid to crystalline phase, we have conducted millisecond order time-resolved x-ray diffraction experiments with a two-dimensional detector. The structural variations observed during the solidification of the Fe83C17alloy were identified as the phase transformation process expected from the Fe-C phase diagram. As for the Fe83B17alloy, it was revealed that a metastable phase composed of Fe23B6compound was precipitated as a primary crystalline phase from the undercooled liquid. In addition, decomposition of the metastable Fe23B6phase showed dependence on the cooling rate of the sample. At the cooling rate of 30 K/s, the Fe23B6phase decomposed to bcc-Fe and Fe2B phases with decreasing temperature. On the contrary, at the cooling rate of 180 K/s, the metastable Fe23B6phase remained in spite of an appearance of the bcc-Fe phase. By comparing the primary crystalline phase between the Fe83C17and the Fe83B17alloys, we suggest that the formability of the metastable Cr23C6-type compound is closely related with the glass-forming ability of Fe-metalloid binary alloys.

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Amorphous and Metastable Phase Formation in Systems with Positive Heats of Mixing using High-Rate Sputter Deposition

MRS Proceedings ◽

10.1557/proc-128-231 ◽

1988 ◽

Vol 128 ◽

Cited By ~ 3

Author(s):

H. F. Rizzo ◽

A. Echeverria ◽

T. B. Massalski ◽

H. Baxi

Keyword(s):

Metastable Phase ◽

Sputter Deposition ◽

High Rate ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Heats Of Mixing ◽

Metastable Phase Formation ◽

Atomic Radii ◽

Deposition Techniques

ABSTRACTThe triode sputtering technique and a “split-target” arrangement were used to produce metastable crystalline and amorphous phases in the Cu-W, Mo-Cu, Ag-Fe, Ag-Cu, Pu-Ta and Pu-V systems. These systems all exhibit liquid and solid immiscibility and have positive heats of mixing and atomic radii that differ by at least 10%. The sputtered coatings, whose thickness varied between 25 and 200 microns, were formed at deposition rates between 35 and 200 Å/s. They were characterized using x-ray diffraction, TEM, microprobe, microhardness, and DSC techniques. The observed amorphous and metastable solid solution phases are discussed in terms of predicated heats of formation for these phases using Miedema's thermodynamic approximations [1] that include chemical, elastic, and structural contributions. Differences in compositional ranges observed by high rate sputter deposition compared to other vapor deposition techniques (e.g., coevaporation) appeared to arise as a result of processes that occur during deposition or immediately following deposition.

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Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

Journal of Electronic Materials ◽

10.1007/s11664-021-09067-4 ◽

2021 ◽

Author(s):

A. Leineweber ◽

M. Löffler ◽

S. Martin

Keyword(s):

Phase Equilibria ◽

Electron Backscatter Diffraction ◽

Metastable Phase ◽

Stable Phase ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Ordered Phases ◽

Backscatter Diffraction ◽

Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

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