Xanes and Exafs Analysis of Ball-Milled Fe-Ni

2001 ◽  
Vol 678 ◽  
Author(s):  
P.J. Schilling ◽  
R.C. Tittsworth ◽  
V. Palshin ◽  
J. Xu ◽  
E. Ma ◽  
...  
Keyword(s):  
Phase Region ◽  
Heat Of Mixing ◽  
Face Centered Cubic ◽  
Two Phase ◽  
Exafs Analysis ◽  
Nano Crystalline ◽  
Atom Pairs ◽  
Face Centered ◽  
Iron Nickel Alloys ◽  
Xanes Analysis

AbstractEXAFS and XANES analysis have been applied in a study of ball-milled nano-crystalline iron-nickel alloys prepared with overall compositions spanning the two-phase region. EXAFS analysis was used to determine bond distances for like and unlike atom pairs in single phase face-centered cubic Fe-Ni alloys, demonstrating the presence of bond dilation for unlike neighbors. Using XANES analysis, the compositions of the two coexisting solid solutions were determined to characterize the ball-milled two-phase region. The compositions of the coexisting face-centered and body-centered cubic phases were found to be consistent with the overall composition of the mixture. The results obtained for the negative heat-of-mixing Fe-Ni system were used for comparison to the positive heat-of-mixing Fe-Cu system.

Formation and morphology of Kurnakov type D022 compound in disordered face-centered cubic γ–(Ni, Fe) matrix alloys

2006 ◽  
Vol 21 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Akane Suzuki ◽  
Masao Takeyama
Keyword(s):  
Strain Ratio ◽  
Misfit Strain ◽  
Phase Region ◽  
Partial Replacement ◽  
Invariant Line ◽  
Face Centered Cubic ◽  
Two Phase ◽  
Two Factors ◽  
Face Centered ◽  
Two Phases

Formation and morphology of D022 compound Ni3V in γ face-centered cubic (fcc) matrix phase were investigated to understand fundamentals for controlling microstructure of alloys strengthened by Kurnakov-type geometrically close-packed (GCP) intermetallics. The D022 phase with plate-shaped morphology coherently precipitates in the γ + D022 two-phase region above the T0 line in Ni–V binary alloys. Due to the negative and positive lattice misfits along the a-axis and the c-axis of D022 (δa < 0 < δc), an invariant line exists between the two phases, and the morphology of D022 phase is changeable by controlling the two factors; the misfit strain ratio δc/δa is a decisive factor to determine the habit plane defined by the invariant line and one of the a-axes of D022, whereas the magnitude of |δa| is responsible for the shape of D022 phase with either prism or plate. These findings were extended to Ni–Fe–Nb–V system by partial replacement of Ni and V with Fe and Nb, respectively.

Metastable copper-chromium alloy films

1992 ◽  
Vol 7 (6) ◽  
pp. 1370-1376 ◽  
Author(s):  
A.P. Payne ◽  
B.M. Clemens
Keyword(s):  
Phase Transition ◽  
Grazing Incidence ◽  
Phase Region ◽  
Heat Of Mixing ◽  
Chromium Alloy ◽  
Two Phase ◽  
Bcc Lattice ◽  
Bcc Structure ◽  
Nonequilibrium States ◽  
Cr System

Due to the large positive heat of mixing associated with the Cu–Cr binary system, solid solutions exist only as nonequilibrium states. In this study, a series of metastable Cu–Cr alloys ranging in composition from 14.1 to 75.4% copper was fabricated by sputter deposition. Symmetric, asymmetric, and grazing incidence x-ray diffraction geometries were used to trace the phase transition from bcc to fcc crystal structures with increasing Cu fraction. It is shown that the transition takes place not by a two-phase region suggested by equilibrium thermodynamics, but rather through gradual disordering of the bcc lattice as copper atoms are substitutionally accommodated. At a critical saturation near 71% Cu, the bcc structure becomes unstable relative to the fcc and a phase transition occurs. The free energies of the kinetically constrained Cu–Cr system are modeled and the results are found to agree well with observed behavior.

Preparation and Electrical Properties of Interconnect Material Made by Substituting Mixed Rare Earth Oxides (Sm2O3, Gd2O3, Eu2O3 and CeO2) for La2O3 in La

2007 ◽  
Vol 336-338 ◽  
pp. 448-451
Author(s):  
Hong Hai Zhong ◽  
Ji Gui Cheng ◽  
Xing Qin Liu ◽  
Guang Yao Meng
Keyword(s):  
Rare Earth ◽  
Fluorite Structure ◽  
Rare Earth Oxides ◽  
Ignition Process ◽  
Face Centered Cubic ◽  
Two Phase ◽  
Auto Ignition ◽  
Electrical Conductivities ◽  
Face Centered ◽  
Interconnect Material

La1-xCaxCrO3 (0.1≤ x ≤ 0.4) is usually used as interconnect material for solid oxide fuel cells (SOFCs). In this paper, composite material, the two-phase mixtures of face-centered cubic fluorite structure CayCe1-yO2-y (0 ≤ y≤ 0.2) and orthorhombic perovskite structure [Sm(Eu,Gd)]1-zCazCrO3 (0 < z < 0.3), was prepared by an auto-ignition process in which mixed rare earth oxides (Sm2O3, Gd2O3, Eu2O3 and CeO2) are substituted for La2O3 in La1-xCaxCrO3. The direct current (DC) four-probe technique measurement indicated that the electrical conductivities of specimens increased along with the increase of Ca2+ content (x), especially when x=0.3 and 0.4. The material (x=0.4, about 94% relative density) showed excellent electrical conductivities of 48 Scm-1 in air and 13 Scm-1 in H2 (purity 99.999%) at 700°C respectively, which is about 3 times as high as that of La0.7Ca0.3CrO3.

A Study On High Coercivity And Lio Ordered Phase In Copt And Fept Thin Films

1999 ◽  
Vol 562 ◽  
Author(s):  
R. A. Ristau ◽  
K. Barmak ◽  
L. H. Lewis ◽  
K. R. Coffey ◽  
J. K. Howard
Keyword(s):  
Quantum Interference ◽  
Volume Fraction ◽  
Magnetic Domain ◽  
Dark Field ◽  
High Coercivity ◽  
Face Centered Cubic ◽  
Two Phase ◽  
Transmission Electron ◽  
Face Centered ◽  
The Relationship

ABSTRACTThis study relates the microstructure of equiatomic binary alloys of CoPt and FePt with their room-temperature hysteretic magnetic properties, particularly their high coercivity. A transformation from an atomically disordered, face-centered-cubic structure to the Li0 ordered structure occurred during post-deposition annealing and was characterized using digital analysis of dark-field transmission electron microscopy (TEM) images. The transformation was observed to follow first-order nucleation and growth kinetics, and the ordered volume fraction transformed was quantified at numerous points during the transformation. The ordered volume fraction was then compared to the magnetic coercivity data obtained from a superconducting quantum interference device (SQUID) magnetometer. Although the relationship most commonly described in the literature is that the highest coercivity corresponds to a two phase ordered/disordered mixture, the maximum value for coercivity in this study was found to correspond to the fully ordered state. Furthermore, in samples that were less than fully ordered, a direct relationship between ordered volume fraction and coercivity was observed. The proposed mechanism for the high coercivity in these films is an increasing density of magnetic domain wall pinning sites concurrent with an increasing fraction of ordered phase.

Magnetic moment of iron–nickel invar alloys from 4 to 80 K

1970 ◽  
Vol 48 (3) ◽  
pp. 264-274 ◽  
Author(s):  
R. W. Cochrane ◽  
G. M. Graham
Keyword(s):  
Magnetic Moment ◽  
Nickel Alloys ◽  
Face Centered Cubic ◽  
Invar Alloys ◽  
Spin Wave Excitations ◽  
Iron Nickel ◽  
Face Centered ◽  
The Moment ◽  
Iron Nickel Alloys ◽  
The Magnetic Field

The magnetic moment of several ferromagnetic face-centered-cubic iron–nickel alloys in the invar region have been investigated at low temperatures, as a function of both the magnetic field and the temperature. A vibrating-sample magnetometer was used, for which relative changes in the moment of 3 parts in 105 could be resolved. Such resolution has permitted a detailed analysis of the temperature dependence of ΔM/M, the relative deviation of the magnetic moment from its value at 0 K, in terms of a contribution arising from spin-wave excitations, varying as T3/2, and one from single-particle excitations, varying as T2, both of these at constant volume, together with a term describing the effect of volume dilation on the moment. The fits to the data for H = 10 kOe yield, for 34 at. % Ni:[Formula: see text]and for 40 at. %Ni:[Formula: see text]

Studies on Extended Dislocation Nodes in a ζ-Phase Silver-Tin Alloy

1967 ◽  
Vol 25 ◽  
pp. 304-305
Author(s):  
L. K. Ives ◽  
A. W. Ruff
Keyword(s):  
Alloy System ◽  
Solute Concentration ◽  
Phase Region ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Two Phase ◽  
The Face ◽  
Extended Dislocation

A determination of the intrinsic stacking fault energy as a function of composition has been previously reported for the face-centered-cubic phase in the silver-tin alloy system. The method involved direct measurements on extended dislocation nodes observed by transmission electron microscopy in alloys containing from 0 to 7.8 at.% tin. The stacking fault energy γ was found to decrease from a value of 22.8 erg/cm3 for silver to 4.2 erg/cm2 for the 7.8 at.%. alloy. Figure 1 shows the phase diagram for this system. At room temperature, the α-phase limit occurs at about 8.5 to 9 at.%. tin. A two-phase region extends to approximately 11.5 at.% followed by the ζ- Ag Sn phase region which exists to about 17 at.% tin. A series of hexagonal ζ alloys of various compositions are presently under study to determine the variation of the stacking fault energy with composition. Preliminary results indicate that the stacking fault energy increases with increasing solute concentration in the ζ-phase region. Extended dislocation nodes have been observed in all the ζ alloys, together with extended ribbons in the dilute alloys. This paper will consider only the results obtained on the most dilute alloy (12 at.% tin) and compare them with the a-phase results.

Observation of tweed microstructures in Ni-Al-Fe alloys

1989 ◽  
Vol 47 ◽  
pp. 676-677
Author(s):  
P. R. Munroe ◽  
I. Baker
Keyword(s):  
Single Phase ◽  
Thin Foil ◽  
Face Centered Cubic ◽  
Two Phase ◽  
Preparation Conditions ◽  
Structural Applications ◽  
B2 Phase ◽  
Fe Alloys ◽  
Face Centered ◽  
B2 Structure

Ni-Fe-Al alloys are currently being considered for structural applications in the aerospace industry. Two compositions in particular Ni-30Al-20Fe and Ni-20Al-30Fe (in at. %) have generated the most interest. The former alloy is a single phase ordered body-centered cubic or B2 structure and the latter alloy has a B2 + Ll2 (ordered face-centered cubic) two-phase microstructure. X-ray microanalysis performed on Ni-20Al-30Fe has shown that the compostion of the B2 phase is Ni-30Al-20Fe, the same composition as the single phase alloy, and the compostion of the Ll2 phase is Ni-12Al-40Fe. This paper reports upon the observation of tweed microstructures in both alloys.The alloys were cast, canned in mild steel, extruded to rod at 1000°C and then cooled in sand. Details of thin foil preparation conditions have been reported before . Foils were examined in a JEOL 100CX operating at 100kV.Selected area diffraction (SAD) patterns from the B2 phase in Ni-20Al-30Fe(fig.1) exhibited streaking <110> directions, similar to the SAD patterns obtained from the B2 phase in Ni-37at%Al where a tweed microstructure was also observed.

scholarly journals Structural characterization and nanoscale strain field analysis of α/β interface layer of a near α titanium alloy

2021 ◽  
Vol 10 (1) ◽  
pp. 1197-1207
Author(s):  
Longlong Lu ◽  
Yanmin Zhang ◽  
Kexing Song ◽  
Xiuhua Guo ◽  
Yan Li ◽  
...  
Keyword(s):  
Strain Field ◽  
Phase Interface ◽  
Interface Layer ◽  
Phase Region ◽  
Field Analysis ◽  
Face Centered Cubic ◽  
Β Phase ◽  
Α Phase ◽  
Face Centered ◽  
Fcc Phase

Abstract In this article, the structural and nanoscale strain field of the α/β phase interface layer in Ti80 alloy were studied by using high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA). The α/β interface layer was observed in forged and different annealed Ti80 alloys, which is mainly composed of lamellar face-centered cubic (FCC) phase region and α′ + β region. The FCC phases between α and β phases show a twin relationship, and the twinning plane is ( 1 1 ¯ 1 ) (1\bar{1}1) . The orientation relationship of the β phase, the α phase, and the FCC phase is (110)β//(0001)α// ( 1 1 ¯ 1 ) (1\bar{1}1) FCC and [ 1 ¯ 11 \bar{1}11 ]β//[ 2 1 ¯ 1 ¯ 0 2\bar{1}\bar{1}0 ]α//[011]FCC. The nanoscale strain field of FCC + α and β + α′ regions was analyzed by using the GPA technology. The FCC + α region shows more significant strain gradient than the α′ + β region, and ε FCC > ε α, ε α′ > ε β. The influence of element addition on the formation mechanism of the FCC phase was discussed. The addition of Zr promotes the formation of the FCC phase by inducing lattice distortion and reducing the stacking fault energy of the α phase. In addition, the Al element forms an obvious concentration gradient around the interface layer during the cooling process of the alloy, which provides a driving force for the formation of the FCC phase.

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