In Situ Observation of Diffusion Behavior and Microstructural Evolution on Interfaces in Al/Cu Bimetal

Synchrotron X-ray radiography was used to in situ study the diffusion behavior and microstructural evolution of Al/Cu bimetal. The interface diffusion, dendritic/eutectic growth and the formation of intermetallic compounds around the Al/Cu bimetal interface were analyzed. During the isothermal diffusion process, a liquefied transition zone at the interface with a concentration gradient was formed when the Cu concentration exceeded eutectic composition of Al-Cu alloy. During the solidification of transition zone, the growth sequence of α-Al dendrites and eutectic structure were mainly dominated by the variation of Cu concentration and thermal field according to the temperature of the liquidus line of the equilibrium phase diagram. Finally, the transition zone around the interface were identified to be I (α-Al), II (Al+Al2Cu), III (Al2Cu) and IV (Al2Cu, AlCu and Al4Cu9), respectively.

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Metastable Phase Equilibria in Co-Deposited Ni1−xZrx Thin Films

MRS Proceedings ◽

10.1557/proc-230-21 ◽

1991 ◽

Vol 230 ◽

Author(s):

J. B. Rubin ◽

R. B. Schwarz

Keyword(s):

Thin Films ◽

Cooling Rate ◽

Metastable Phase ◽

Equilibrium Phase ◽

Equilibrium Phase Diagram ◽

Amorphous Structure ◽

Nucleation Theory ◽

Glass Forming ◽

Constant Heating

AbstractWe determine the glass forming range (GFR) of co-deposited Ni1−xZrx (0 < x < 1) thin films by measuring their electrical resistance during in situ constant-heating-rate anneals. The measured GFR is continuous for 0.10 < x < 0.87. We calculate the GFR of Ni-Zr melts as a function of composition and cooling rate using homogeneous nucleation theory and a published CALPHAD-type thermodynamic modeling of the equilibrium phase diagram. Assuming that the main competition to the retention of the amorphous structure during the cooling of the liquid comes from the partitionless crystallization of the terminal solid solutions, we calculate that for dT/dt = 1012 K s−1, the GFR extends to x = 0.05 and x = 0.96. Better agreement with the measured values is obtained assuming a lower ‘effective’ cooling rate during the condensation of the films.

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Non-Equilibrium Processing of Ni-Si Alloys at High Undercooling and High Cooling Rates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.790-791.22 ◽

2014 ◽

Vol 790-791 ◽

pp. 22-27 ◽

Cited By ~ 3

Author(s):

Andrew M. Mullis ◽

Lei Gang Cao ◽

Robert F. Cochrane

Keyword(s):

Metastable Phase ◽

Equilibrium Phase ◽

Equilibrium Phase Diagram ◽

Eutectic Structure ◽

Eutectic Solidification ◽

Drop Tube ◽

High Undercooling ◽

Cooling Rates ◽

Β Phase ◽

High Cooling Rates

Melt encasement (fluxing) and drop-tube techniques have been used to solidify a Ni-25 at.% Si alloy under conditions of high undercooling and high cooling rates respectively. During undercooling experiments a eutectic structure was observed, comprising alternating lamellae of single phase γ (Ni31Si12) and Ni-rich lamellae containing of a fine (200-400 nm) dispersion of β1-Ni3Si and α-Ni. This is contrary to the equilibrium phase diagram from which direct solidification to β-Ni3Si would be expected for undercoolings in excess of 53 K. Conversely, during drop-tube experiments a fine (50 nm) lamellar structure comprising alternating lamellae of the metastable phase Ni25Si9 and β1-Ni3Si is observed. This is also thought to be the result of primary eutectic solidification. Both observations would be consistent with the formation of the high temperature form of the β-phase (β2/β3) being suppressed from the melt.

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Synthesis of multicomponent metallic layers during impulse plasma deposition

Materials Science-Poland ◽

10.1515/msp-2015-0077 ◽

2015 ◽

Vol 33 (4) ◽

pp. 841-846 ◽

Cited By ~ 2

Author(s):

Katarzyna Nowakowska-Langier ◽

Rafal Chodun ◽

Krzysztof Zdunek

Keyword(s):

Plasma Deposition ◽

Equilibrium Phase ◽

Nanocrystalline Structure ◽

Equilibrium Phase Diagram ◽

Pulsed Plasma ◽

Plasma Generation ◽

Cu Alloy ◽

Supersaturated Solid Solutions ◽

Electrical Pulses ◽

Complete Ionization

AbstractPulsed plasma in the impulse plasma deposition (IPD) synthesis is generated in a coaxial accelerator by strong periodic electrical pulses, and it is distributed in a form of energetic plasma packets. A nearly complete ionization of gas, in these conditions of plasma generation, favors the nucleation of new phase of ions and synthesis of metastable materials in a form of coatings which are characterized by amorphous and/or nanocrystalline structure. In this work, the Fe–Cu alloy, which is immiscible in the state of equilibrium, was selected as a model system to study the possibility of formation of a non-equilibrium phase during the IPD synthesis. Structural characterization of the layers was done by means of X-ray diffraction and conversion-electron Mössbauer spectroscopy. It was found that supersaturated solid solutions were created as a result of mixing and/or alloying effects between the layer components delivered to the substrate independently and separately in time. Therefore, the solubility in the Fe–Cu system was largely extended in relation to the equilibrium conditions, as described by the equilibrium phase diagram in the solid state.

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Microstructural Evolution of Mo-Si-B Ternary Alloys through Heat Treatment at 1800°C

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.278.527 ◽

2011 ◽

Vol 278 ◽

pp. 527-532 ◽

Cited By ~ 8

Author(s):

Kyosuke Yoshimi ◽

Soeng Ho Ha ◽

Kouichi Maruyama ◽

Rong Tu ◽

Takashi Goto

Keyword(s):

Heat Treatment ◽

Phase Diagram ◽

Solid Solution ◽

Microstructural Evolution ◽

Alloy Composition ◽

Equilibrium Phase ◽

Secondary Phase ◽

Equilibrium Phase Diagram ◽

The Other ◽

Ternary Alloys

First of all, the as-cast microstructures of Mo-rich Mo-Si-B ternary alloys were investigated around the triple junction point of the primary Mo solid solution, Mo5SiB2 and Mo2B in this work, based on the liquidus projections of the Mo-Si-B system which have been reported in earlier studies. Subsequently, their microstructural evolution through heat treatment was investigated. Since Mo2B crystallizes out during solidification into a primary or secondary phase even though the alloy composition lies in the triangle of Mo-Mo5SiB2-Mo3Si in the Mo-Si-B equilibrium phase diagram, the as-cast microstructures include the non-equilibrated Mo2B in wide compositional ranges. However, Mo2B was completely decomposed during heat treatment at 1800 °C for 24 h and this contributed to the development of homogeneous, fine microstructures. On the other hand, since Mo2B was not decomposed perfectly during 24 h of 1600 °C heat treatment, as-cast microstructures largely remained. Therefore, it is realized that the heat treatment at 1800 °C is necessary to obtain well-developed microstructures of Mo-Si-B alloys.

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On the Solid-Fluid Transition Zone in Welding Analysis

Journal of Engineering Materials and Technology ◽

10.1115/1.2902150 ◽

1993 ◽

Vol 115 (1) ◽

pp. 17-23 ◽

Cited By ~ 5

Author(s):

Y. Chen ◽

I. C. Sheng

Keyword(s):

Transition Zone ◽

Equilibrium Phase ◽

Fluid Motion ◽

Welding Process ◽

Mixture Theory ◽

Equilibrium Phase Diagram ◽

Material Point ◽

Point Of View ◽

Energy Equations ◽

Fluid Phases

Equilibrium and energy equations have been developed in describing the solid-fluid transition zone during the melting and solidification of the binary alloys. Due to the existence of the transition region exhibiting both solid and fluid phases at the same material point from continuum point of view, mixture theory was utilized to analyze the region. Unlike the Stefan problem, the latent heat due to the phase change appears as a source term in the heat equation. The molten fluid is treated as a thermoviscous and incompressible fluid, whereas the solid is thermoviscoplastic described by the Bodner-Partom/Walker type of constitutive equations. Thermal mechanical behaviors of the solid and the fluid phases are determined separately because of insignificant mechanical interactions between them. Volume fractions of the phases are obtained according to the equilibrium phase diagram. The simulation process of the transition zone and the welding process was carried out by FEM. The molten fluid motion, the sizes, and the contours of the transition zone were presented.

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In-Situ Time-Resolved X-Ray Studies of Eutectic Crystallization in Amorphous Fe1−xBx and Co1−xZrx

MRS Proceedings ◽

10.1557/proc-237-159 ◽

1991 ◽

Vol 237 ◽

Author(s):

Henry E. Fischer ◽

S. Brauer ◽

M. Sutton ◽

J. Ström-Olsen ◽

A. Zaluska ◽

...

Keyword(s):

Small Angle ◽

Large Angle ◽

Structural Evolution ◽

Eutectic Growth ◽

Eutectic Structure ◽

Time Resolved ◽

X Ray ◽

Eutectic Crystallization ◽

Diffraction Patterns

ABSTRACTUsing a millisecond time-resolved x-ray scattering technique at the National Synchrotron Light Source, we have simultaneously obtained in situ both large-angle (LAXS) and small-angle (SAXS) diffraction patterns for isothermal crystallization of amorphous Fe1−xBx (0.16 < x < 0.21) and Co1−xZrx (0.08 < x < 0.11). The large-angle x-ray data are analyzed to determine which of the two crystalline products nucleate first in each compound, and also to assess the evidence for eutectic growth as shown by a time-independent ratio of volume fractions of these product phases. The small-angle data give the length scales of the eutectic structure as well as information about its time evolution. Combining our x-ray results with TEM studies, we examine the effects of changes in temperature and composition on the structural evolution of both the amorphous and crystalline phases.

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Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153415 ◽

1989 ◽

Vol 47 ◽

pp. 288-289

Author(s):

J. R. Reed ◽

D. J. Michel ◽

P. R. Howell

Keyword(s):

Thin Foil ◽

Icosahedral Symmetry ◽

Ion Milling ◽

Cu Alloy ◽

Thin Foils ◽

Heat Treated ◽

Aluminum Solid Solution ◽

In Situ Heating ◽

The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

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