The Earliest Stage of the Solid State Amorphization Reaction in the Zr-Co System

ABSTRACTBased on atom probe field ion microscopy (AP/FIM) studies, electromotive force (EMF) measurements and CALPHAD calculations we discuss the earliest stage of the solid state amorphization reaction (SSAR) in Zr/Co-layers. The AP measurements show that two amorphous phases are formed at the Zr/Co interface from the early stages of the reaction. The metastable two phase field between these amorphous phases is shown by direct measurement of the chemical potential of Zr in amorphous co-sputtered ZrCo alloys by the EMF method. The comparison between the atom probe data and the CALPHAD calculation shows that the interfaces between the different layers are far away from metastable equilibrium in the beginning of the reaction. The amorphous phase formation at the Zr/Co interface and in the hcp-Zr grain boundary is preceded by a supersaturation of the hep ZrCo solid solution that transforms polymorphically into the amorphous state.

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High resolution studies of the solid state amorphization reaction in the ZrCo system with the atom probe/field ion microscope

MRS Proceedings ◽

10.1557/proc-343-223 ◽

1994 ◽

Vol 343 ◽

Cited By ~ 1

Author(s):

Susanne Schneider ◽

Ralf Busch ◽

Konrad Samwer

Keyword(s):

Solid State ◽

Single Crystal ◽

Grain Boundaries ◽

Amorphous Phase ◽

Rutherford Backscattering Spectrometry ◽

Atom Probe ◽

Nanometer Scale ◽

Probe Field ◽

Field Ion Microscope ◽

State Amorphization

ABSTRACTThe atom probe/field ion microscope is introduced as a new powerful investigation device to study the early stages of the solid state amorphization reaction (SSAR). A bilayer of Zr and Co was condensed under UHV conditions on W wire tips and analyzed in a field ion microscope (FIM) combined with an atom probe (AP). The reaction of Co with Zr has been studied at room temperature. FIM pictures and AP analysis have shown that even at low temperatures an amorphous phase is formed at the Zr/Co interface and in the Zr grain boundaries. In these areas concentration profiles have been taken on a nanometer scale. Most likely, the extended solid solution of Co found in α- Zr grain boundaries causes the formation of the amorphous phase. Further, Rutherford backscattering spectrometry (RBS) suggests that even point defects and dislocations at the surface of an α- Zr single crystal are sufficient to initiate the SSAR between a polycrystalline Co layer vapour- deposited onto that single crystal.

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A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011742x ◽

1985 ◽

Vol 43 ◽

pp. 70-71

Author(s):

M.G. Burke ◽

M.K. Miller

Keyword(s):

Low Temperature ◽

Microstructural Characterization ◽

Superlattice Reflection ◽

High Volume ◽

Atom Probe ◽

Dark Field ◽

Miscibility Gap ◽

Second Phase ◽

Two Phase ◽

Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

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Microstructural Characterization of Rapidly Solidified Ultrahigh Strength Aluminum Alloys

Microscopy and Microanalysis ◽

10.1017/s1431927600020614 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 98-99

Author(s):

D. H. Ping ◽

K. Hono ◽

A. Inoue

Keyword(s):

Rapid Solidification ◽

Microstructural Characterization ◽

Atom Probe ◽

Probe Field ◽

Amorphous Phases ◽

Ultrahigh Strength ◽

Icosahedral Phases ◽

Transmission Electron ◽

Solidification Processes ◽

Rapidly Solidified

Recently, Inoue et al. succeeded in fabricating ultrahigh-strength Al-based alloys consisting of a nanoscale mixture of α-Al and amorphous phases or a mixture of a-Al, amorphous and icosahedral phases in Al-TM-Ce, Al-TM-Ln (TM: transition metals) and Al-Cr-Co-Ce systems by rapid solidification [1-3]. In order to understand the mechanism of the nanoscale microstructural evolution during the rapid solidification processes in these nanocomposite alloys, we have characterized the microstructures of rapidly solidified Al94.5Cr3Co1.5Ce1 and Al96V4Fe2 alloys by atom probe field ion microscopy (APFIM) and high resolution transmission electron microscopy (HREM).TEM investigations have revealed that the as-quenched Al94.5Cr3Co1.5Ce1 alloy is composed of a nanoscale mixture of amorphous and α-Al. A typical TEM bright field micrograph is shown in Fig. 1. The microdiffraction patterns taken at various locations in the darkly contrasted region have shown that the region consists of a few interconnected α-Al grains and many localized amorphous regions which are trapped within the Al grains.

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Spinodal Decomposition in Fe-Cr-Co Alloys

MRS Proceedings ◽

10.1557/proc-21-557 ◽

1982 ◽

Vol 21 ◽

Author(s):

S. S. Brenner ◽

P. P. Camus ◽

M. K. Miller ◽

W. A. Soffa

Keyword(s):

Phase Separation ◽

Spinodal Decomposition ◽

Atom Probe ◽

Continuous Phase ◽

Miscibility Gap ◽

Two Phase ◽

Probe Field ◽

Long Wavelength ◽

Composition Fluctuations ◽

Kinetics Of

Continuous phase separation or spinodal decomposition occurs within a miscibility gap through the selective amplification of long wavelength concentration waves to produce a two-phase modulated microstructure. To comprehensively study the formation of these modulated microstructures and the kinetics of continuous phase separation the behavior of the composition fluctuations in the decomposing material should be monitored directly. The atom probe field-ion microscope is an ideal instrument for this type of investigation of fine-scale microstructures because of its ultra-high spatial resolution and microchemical analysis capability.

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Methods of amorphization and investigation of the amorphous state

Acta Pharmaceutica ◽

10.2478/acph-2013-0026 ◽

2013 ◽

Vol 63 (3) ◽

pp. 305-334 ◽

Cited By ~ 62

Author(s):

Tomaž Einfalt ◽

Odon Planinšek ◽

Klemen Hrovat

Keyword(s):

Nuclear Magnetic Resonance ◽

Infrared Spectroscopy ◽

Solid State ◽

Terahertz Spectroscopy ◽

Amorphous State ◽

Amorphous Form ◽

X Ray ◽

State Amorphization ◽

Crystalline Hydrates ◽

And Calorimetry

Abstract The amorphous form of pharmaceutical materials represents the most energetic solid state of a material. It provides advantages in terms of dissolution rate and bioavailability. This review presents the methods of solid- -state amorphization described in literature (supercooling of liquids, milling, lyophilization, spray drying, dehydration of crystalline hydrates), with the emphasis on milling. Furthermore, we describe how amorphous state of pharmaceuticals differ depending on the method of preparation and how these differences can be screened by a variety of spectroscopic (X-ray powder diffraction, solid state nuclear magnetic resonance, atomic pairwise distribution, infrared spectroscopy, terahertz spectroscopy) and calorimetry methods.

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Atom Probe Field Ion Microscopy of Poly Synthetically Twinned Titanium Aluminide

Microscopy and Microanalysis ◽

10.1017/s1431927600020638 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 102-103

Author(s):

D. J. Larson ◽

M. K. Miller ◽

H. Inui ◽

M. Yamaguchi

Keyword(s):

Mechanical Properties ◽

Titanium Aluminide ◽

Lamellar Microstructure ◽

Atom Probe ◽

Ordered Structure ◽

Two Phase ◽

Probe Field ◽

Tial Alloys ◽

Structural Applications ◽

Single Set

Two phase γ-based TiAl alloys are attractive for structural applications at high temperatures because they possess good elevated-temperature mechanical properties, low density, and good creep and oxidation resistance. The microstructures of these alloys consist of plates of the near equiatomic γ phase (L10-ordered structure) and the Ti3Al α2 phase (D019-ordered structure). It is of great interest to study the details of the lamellar α2+γ microstructure because the interface stability is the key to providing a usable high temperature material.Polysynthetically twinned (PST) TiAl crystals have been developed in order to systematically study the lamellar microstructure. These PST materials contain no high angle grain boundaries and have an single set of aligned lamellae of a α2 and γ phases, as shown in Fig. 1. Therefore, PST samples facilitate the study of the dependence of mechanical properties on lamellar structure by providing a known, consistent set of aligned lamellae.

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Calculation of Glass-Forming Ability in the Ni-Zr and Ni-Ti Systems from Interatomic Potentials

MRS Proceedings ◽

10.1557/proc-644-l4.2 ◽

2000 ◽

Vol 644 ◽

Author(s):

W.S. Lai ◽

B.X. Liu

Keyword(s):

Solid State ◽

Solid Solutions ◽

Amorphous State ◽

Md Simulations ◽

Interatomic Potentials ◽

Glass Forming ◽

Lindemann Criterion ◽

Amorphous States ◽

State Amorphization ◽

Amorphous Interlayer

AbstractFor the Ni-Zr and Ni-Ti systems, Molecular-dynamics (MD) simulations are conducted to compare the relative stability of the terminal solid solutions versus the corresponding amorphous states as a function of solute concentrations. It turns out that the terminal solid solutions transform into an amorphous state spontaneously when the solute concentrations are beyond the maximum allowable values, i.e. the critical solubilities, determined to be 14 at.% Zr in Ni and 25 at.% Ni in Zr for Ni-Zr system and 38 at.% Ti in Ni and 15 at.% Ni in Ti for the Ni-Ti system, respectively. The glass-forming ranges are therefore deduced to be within the respective critical solubilities, i.e. 14-75 at.% Zr and 38-85 at.% Ti for the Ni-Zr and Ni-Ti systems, respectively, which are compatible with those from experiments and/or from the generalized Lindemann criterion. Moreover, MD simulation also reveals that solid-state amorphization does take place and that the growth of the amorphous interlayer follows exactly a t½ law. Besides, a solubility criterion is proposed that the lower the maximum solid solubility the less stable is the lattice of the metal upon solid-state reaction and it can explain the fact that the growing speed of amorphous interlayer toward Ni (melting point = 1528 K) is greater than that directed to the Zr (2128 K) lattice, while it is smaller than that to Ti (1941 K) side.

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Mechanism of Solid-State Amorphization in the Fe-Si-Cu-Mg-O System

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.316.295 ◽

2021 ◽

Vol 316 ◽

pp. 295-299

Author(s):

Nikolai N. Nikul'chenkov ◽

Andrey A. Redikul'tsev ◽

Mikhail L. Lobanov

Keyword(s):

Solid Solution ◽

Solid State ◽

Amorphous State ◽

Continuous Annealing ◽

X Ray Diffraction ◽

Transformation Temperatures ◽

X Ray ◽

Heating And Cooling ◽

Cu Alloy ◽

State Amorphization

Solid-state amorphization process occurring at 600-1060 °C continuous annealing was observed by non-ambient x-ray diffraction on Fe-3%Si-0.5%Cu alloy surface with MgO as thermostable coating. The phenomenon was occurred at α→γ transformation temperatures (920-960 °C) in a layer consisting of Si solid solution in α-Fe and oxides (MgFe)2SiO4, (MgFe)O, SiO2. Amorphous state remained both during heating and cooling to 20 °C. Simulation for diffusion amorphization of Fe (Si) solid solution was proposed. Mg2Si complexes are reduced from oxides by hydrogen then transfer to solid solution and solid-state amorphization is occurred.

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Composition Dependence of Solid-State Amorphization Kinetics

MRS Proceedings ◽

10.1557/proc-205-189 ◽

1990 ◽

Vol 205 ◽

Author(s):

W. S. L. Boyer ◽

M. Atzmon

Keyword(s):

Solid State ◽

Amorphous Alloy ◽

Composition Dependence ◽

Composition Range ◽

Metastable Equilibrium ◽

Terminal Phase ◽

Common Tangent ◽

Ni Content ◽

The Common ◽

State Amorphization

AbstractSolid-state amorphization rates have been measured for amorphous Ni1-cMc in contact with the crystalline terminal phase M, (M=Hf or Zr). The interdiffusion coefficient Dis found to depend on the composition of the amorphous phase, with higher Ni content resulting in a higher Dover the composition range Ni67Hf33 to Ni47Hf53. The common tangent composition at which the amorphous alloy is in metastable equilibrium with the terminal crystalline phase is found to be greater than 70 at.% Hf, which is considerably higher than previously reported values. This discrepancy is explained in terms of the interdiffusion coefficient's variation with composition.

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