Decomposition of Unstable Supersaturated Cu90Co10 Solid Solutions

1995 ◽  
Vol 400 ◽  
Author(s):  
Ralf Busch ◽  
Frank Gärtner ◽  
Christine Borchers ◽  
Peter Haasen ◽  
Rüdiger Bormann
Keyword(s):  
Heterogeneous Nucleation ◽  
Atom Probe ◽  
Nucleation And Growth ◽  
Growth Behavior ◽  
Nanometer Scale ◽  
Probe Field ◽  
Chemical Ordering ◽  
Transmission Electron ◽  
Composition Profiles ◽  
Ion Microscopy

AbstractHomogeneous Cu90Co10 alloys were prepared by rapid solidification using the meltspin technique. The decomposition process of this highly supersaturated unstable solid solution was investigated on a nanometer scale using a combination of atom probe field ion microscopy (AP/FIM) analyses and transmission electron microscopy.Annealing of the Cu90Co10 alloys at 440°C for various times leads to the formation of a compositional modulated microstructure within the grains. The composition profiles determined by AP/FIM analyses clearly exclude a classical nucleation and growth behavior of Co-rich particles. The microstructure is modulated with two different wavelengths. In addition, chemical ordering perpendicular to [111] directions of the fee lattice is observed.At the grain boundaries of this alloy, heterogeneous nucleation of pure Co particles is observed. This heterogeneous nucleation process competes with the decomposition within the grains.

Oxygen induced chemical ordering and ultrafine lamellar structure formation in a Ti-48 at. % Al alloy

2002 ◽  
Vol 753 ◽  
Author(s):  
Williams Lefebvre ◽  
Annick Loiseau ◽  
Alain Menand
Keyword(s):  
Structure Formation ◽  
Lamellar Structure ◽  
Atom Probe ◽  
Nucleation And Growth ◽  
Al Alloy ◽  
Microstructure Development ◽  
Chemical Ordering ◽  
Transmission Electron ◽  
Critical Oxygen ◽  
Means Of Transmission

ABSTRACTInfluence of oxygen on the microstructure development of a Ti-48 at. % Al alloy has been investigated by means of transmission electron microscopy and 1D atom probe. Oxygen is found to significantly increase the temperature of the α → α2 chemical ordering reaction. As a consequence, above a critical oxygen content, the α → α2 transformation is substituted to the α → γm massive transformation when the Ti-48 Al alloy is quenched from the single a-phase field. In such a case, our pervious work has shown that the alloy exhibits a fully (α2 + γ) ultrafine lamellar structure. The present work gives a complete description of the ultrafine lamellar structure formation which, in opposition to the classical lamellar structure formation, involves an intragranular nucleation and growth of the γ phase within the α2 matrix.

Effect of Gold Addition on the Nanostructure of Amorphous Fe–Zr–B Alloy

2000 ◽  
Vol 15 (6) ◽  
pp. 1271-1279 ◽  
Author(s):  
Y. Zhang ◽  
U. Czubayko ◽  
N. Wanderka ◽  
F. Zhu ◽  
H. Wollenberger
Keyword(s):  
Amorphous Alloys ◽  
Crystallization Process ◽  
Amorphous Matrix ◽  
Early Stage ◽  
Primary Crystallization ◽  
Atom Probe ◽  
Probe Field ◽  
Au Clusters ◽  
Transmission Electron ◽  
Ion Microscopy

The behavior of Au in the course of the primary crystallization process of Fe87Zr7B5Au1 amorphous alloy was examined by use of atom probe field ion microscopy and transmission electron microscopy. In the early stage of crystallization, Au atoms were still distributed uniformly in the amorphous matrix. Au atoms form clusters at a later stage when more α–Fe particles are present. The Au clusters were observed to be separated from α–Fe particles, indicating that Au clusters do not stimulate nucleation of α–Fe particles. During the growth of α–Fe grains, cosegregation of Au and Zr occurred without any influence on the α–Fe grain growth. We conclude that Au addition has no effect on nanocrystallization of Fe–Zr–B amorphous alloys.

Characterizatiom of spinodally decomposed Fe-30.1% Cr-9.9% Co: Part 1

1986 ◽  
Vol 44 ◽  
pp. 580-581
Author(s):  
L. L. Horton ◽  
M. K. Miller ◽  
S. Spooner
Keyword(s):  
Isothermal Aging ◽  
Small Angle Neutron Scattering ◽  
Atom Probe ◽  
Probe Field ◽  
Solution Treated ◽  
Transmission Electron ◽  
Water Quench ◽  
Complementary Nature ◽  
Ion Microscopy

Transmission Electron Microscopy (TEM), Atom Probe Field-Ion Microscopy (APFIM) and Small Angle Neutron Scattering (SANS) have been used to characterize the microstructure of a commercial Fe-30.1 at.% Cr-9.9 at.% Co alloy. One goal of this investigation was to demonstrate the complementary nature of these techniques in solving a difficult materials problem, the characterization of fine scale spinodally-decomposed structures. The alloy was solution treated at 925°C for 140 min followed by water quenching, isothermal aging at 525°C for times of 2, 8, 24, 72, 192, or 485 h and a final water quench. TEM characterizations were performed with Philips EM400T/FEG, Philips EM430T and JEM 120C instruments.

Characterizatiom of spinodally decomposed Fe-30.1% Cr-9.9% Co: Part 2

1986 ◽  
Vol 44 ◽  
pp. 582-583
Author(s):  
S. Spooner ◽  
L. L. Horton ◽  
M. K. Miller
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Atom Probe ◽  
Real Space ◽  
Probe Field ◽  
Α Phase ◽  
Transmission Electron ◽  
Ion Microscopy

Characteristic distances describing the scale of the spinodal microstructure obtained from Transmission Electron Microscopy (TEM), Atom Probe Field Ion Microscopy (APFIM), and Small Angle Neutron Scattering (SANS) are described and compared. These techniques provide a view of the microstructure either directly in real space or indirectly in reciprocal space. The material and its general microstructure are described in Part 1, elsewhere in these proceedings. Only the decomposition of the ferrite phase into a modulated isotropic microstructure consisting of a chromium-enriched α' phase and an iron-rich a phase is considered in this presentation.

scholarly journals A Study of the Phase Decomposition of Fe-Ni-Al-Mo Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
M.K. Miller ◽  
M.G. Hetherington ◽  
J.R. Weertman ◽  
H.A. Calderon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Lattice Parameter ◽  
Al Alloys ◽  
Phase Decomposition ◽  
Probe Field ◽  
Transmission Electron ◽  
The Matrix ◽  
Ion Microscopy

AbstractThe aging of β′ NiAl precipitates in ferritic Fe-Ni-Al alloys has been studied by transmission electron microscopy (TEM) and atom-probe field-ion microscopy (APFIM). The addition of Mo alters the lattice parameter of the phases and segregation of Mo to the interface between the matrix and the particles may alter the interfacial energy. The compositions of the matrix, precipitates and interfaces have been measured by TEM and APFIM. The results are compared.

High-resolution x-ray imaging of small copper-rich precipitates in steels

1988 ◽  
Vol 46 ◽  
pp. 528-529
Author(s):  
J. R. Michael ◽  
K. A. Taylor
Keyword(s):  
Electron Microscopy ◽  
Thermomechanical Processing ◽  
Atom Probe ◽  
Ferrite Matrix ◽  
Scanning Transmission Electron Microscope ◽  
Probe Field ◽  
X Ray ◽  
Subsequent Transformation ◽  
Transmission Electron ◽  
Scanning Transmission

Although copper is considered an incidental or trace element in many commercial steels, some grades contain up to 1-2 wt.% Cu for precipitation strengthening. Previous electron microscopy and atom-probe/field-ion microscopy (AP/FIM) studies indicate that the precipitation of copper from ferrite proceeds with the formation of Cu-rich bcc zones and the subsequent transformation of these zones to fcc copper particles. However, the similarity between the atomic scattering amplitudes for iron and copper and the small misfit between between Cu-rich particles and the ferrite matrix preclude the detection of small (<5 nm) Cu-rich particles by conventional transmission electron microscopy; such particles have been imaged directly only by FIM. Here results are presented whereby the Cu Kα x-ray signal was used in a dedicated scanning transmission electron microscope (STEM) to image small Cu-rich particles in a steel. The capability to detect these small particles is expected to be helpful in understanding the behavior of copper in steels during thermomechanical processing and heat treatment.

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