scholarly journals Phase Transformations in Cu-Zr Multilayers

1993 ◽  
Vol 311 ◽  
Author(s):  
T.T. Weihs ◽  
T.T. Barbee ◽  
M.M. Wall
Keyword(s):  
Phase Transformations ◽  
Equilibrium Phase ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Multilayer Foils ◽  
Short Range Ordering ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter ◽  
Long Range Ordering ◽  
Zr Alloys

ABSTRACTA study of phase transformations is reported for Cu-rich, Cu-Zr multilayer foils that were synthesized using magnetron sputter deposition and annealed using a differential scanning calorimeter. The foils range in composition from 1.6 at% to 9.0 at% Zr and consist of alternate layers of polycrystalline Cu and Zr. Differential scanning calorimetry, X-ray analysis and electron microscopy were used to examine three distinct reactions in the foils: a mixing and an amorphization of the Cu and the Zr, a crystallization to the metastable intermetallic, Cu51Zr14, and a transformation of the Cu51Zr14 phase into the equilibrium phase, Cu9Zr2. The asdeposited layering remained stable during the first two reactions and then broke down in the third reaction as large grains of Cu9Zr2 encompassed the smaller Cu grains. The heats of the reactions and the activation energies of these reactions are measured and are compared to values reported for bulk samples. The measured heats support the observation that amorphous Cu-Zr alloys phase separate and provide evidence that mixing and short range ordering produce 3.5 times more heat than long range ordering when Cu and Zr react and form Cu51Zr14.

Characterization of the Phase Transformations in the Shape Memory Alloy Ni-36 at.% Al

1991 ◽  
Vol 246 ◽  
Author(s):  
J.A. Horton ◽  
E.P. George ◽  
C.J. Sparks ◽  
M.Y. Kao ◽  
O.B. Cavin ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Phase Transformations ◽  
Hot Extrusion ◽  
Exothermic Peak ◽  
Nickel Aluminum ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

AbstractA survey by differential scanning calorimetry (DSC) and recovery during heating of indentations on a series of nickel-aluminum alloys showed that the Ni-36 at.% Al composition has the best potential for a recoverable shape memory effect at temperatures above 100°C. The phase transformations were studied by high temperature transmission electron microscopy (TEM) and by high temperature x-ray diffraction (HTXRD). Quenching from 1200°C resulted in a single phase, fully martensitic structure. The initial quenched-in martensites were found by both TEM and X-ray diffraction to consist of primarily a body centered tetragonal (bct) phase with some body centered orthorhombic (bco) phase present. On the first heating cycle, DSC showed an endothermic peak at 121°C and an exothermic peak at 289°C, and upon cooling a martensite exothermic peak at 115° C. Upon subsequent cycles the 289°C peak disappeared. High temperature X-ray diffraction, with a heating rate of 2°C/min, showed the expected transformation of bct phase to B2 between 100 and 200°C, however the bco phase remained intact. At 400 to 450°C the B2 phase transformed to Ni2Al and Ni5Al3. During TEM heating experiments a dislocation-free martensite transformed reversibly to B2 at temperatures less than 150°C. At higher temperatures (nearly 600°C) 1/3, 1/3, 1/3 reflections from an ω-like phase formed. Upon cooling, the 1/3, 1/3, 1/3 reflections disappeared and a more complicated martensite resulted. Boron additions suppressed intergranular fracture and, as expected, resulted in no ductility improvements. Boron additions and/or hot extrusion encouraged the formation of a superordered bct structure with 1/2, 1/2, 0 reflections.

Evidence of Bulk Nanostructuring in Zr-Based Alloys under Deformation at Temperatures of α↔β Phase Transformations

2010 ◽  
Vol 667-669 ◽  
pp. 629-634
Author(s):  
Margarita Isaenkova ◽  
Yuriy Perlovich ◽  
Vladimir Fesenko ◽  
Olga Krymskaya ◽  
Alexander Zavodchikov
Keyword(s):  
Plastic Deformation ◽  
Phase Transformations ◽  
Texture Features ◽  
X Ray ◽  
Β Phase ◽  
Crystallographic Slip ◽  
Interphase Boundaries ◽  
Grain Fragmentation ◽  
Temperature Rate ◽  
Zr Alloys

The deformation behavior of commercial Zr alloys with 1% and 2,5%Nb under compression at temperatures of the (α+β)-region of Zr-Nb phase diagram is considered on the basis of experimental data obtained by X-ray texture study of deformed samples. Mechanisms, responsible for plastic deformation of alloys by different temperature-rate regimes were determined on the basis of resulting textures. Among these mechanisms there are crystallographic slip and mutual displacements of crystallites along interphase boundaries. The latter mechanism sharply intensifies by grain fragmentation down to nanostructuring under conditions of α«β phase transformations. Texture features of deformed samples testify about interaction of plastic deformation with phase transformations and indicate that due to this interaction compression by optimal regimes promotes the utmost refinement of structure elements.

PHASE TRANSFORMATIONS DURING HEATING OF AMORPHOUS/NANOCRYSTALLINE Ni–Ti POWDERS

2010 ◽  
Vol 24 (09) ◽  
pp. 1137-1140 ◽  
Author(s):  
M. M. VERDIAN ◽  
M. SALEHI ◽  
K. RAEISSI
Keyword(s):  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Phase Transformations ◽  
Low Energy ◽  
Heating Process ◽  
Study Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Niti Phase

Amorphous/nanocrystalline 50 Ni –50 Ti powders were synthesized from elemental Ti and Ni powders by solid state synthesis utilizing low energy mechanical alloying with times up to 100 h. The produced powders were investigated by X-ray diffraction and differential scanning calorimetry to study phase transformations that occurred during heating in the calorimeter. It was found that at the first stage of the heating process, a disordered NiTi phase was formed at temperature of about 400°C. Further investigations indicated that this phase transformed into the Ni 3 Ti and Ti 2 Ni intermetallic compounds after heating at a temperature of about 800°C.

Studying Density vs Ar-pressures for optimization of DC-magnetron sputter deposition of Ni/C multilayers for hard x-ray telescopes

1997 ◽  
Author(s):  
Ahsen M. Hussain ◽  
Suzanne E. Romaine ◽  
Paul Gorenstein ◽  
John E. Everett ◽  
Ricardo J. Bruni ◽  
...  
Keyword(s):  
Sputter Deposition ◽  
X Ray ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter

Beryllium-Based Multilayer Structures

1995 ◽  
Vol 382 ◽  
Author(s):  
D. G. Stearns ◽  
K. M. Skulina ◽  
M. Wall ◽  
C. S. Alford ◽  
R. M. Bionta ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Normal Incidence ◽  
Sputter Deposition ◽  
Multilayer Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter

ABSTRACTMultilayer (ML) structures composed of Mo-Be, Ru-Be and Rh-Be with bilayer periods of - 6 nm have been grown using dc magnetron sputter deposition. The ML microstructure has been characterized using x-ray diffraction and high-resolution transmission electron microscopy, and the normal incidence reflectivity has been measured at soft x-ray wavelengths.

Sputter-deposition and characterization of paramelaconite

2003 ◽  
Vol 18 (7) ◽  
pp. 1535-1542 ◽  
Author(s):  
K. J. Blobaum ◽  
D. Van Heerden ◽  
A. J. Wagner ◽  
D. H. Fairbrother ◽  
T. P. Weihs
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metastable Phase ◽  
Heat Of Formation ◽  
Sputter Deposition ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Multilayer Foils ◽  
Out Of Plane ◽  
Processing Techniques

While processing techniques for deposition of CuOx/Al multilayer foils were being developed, a method for synthesizing paramelaconite (Cu4O3) was serendipitously discovered. These paramelaconite films were successfully synthesized by sputter-deposition from a CuO target. Milligram quantities of uncontaminated material were produced enabling new studies of the morphology, stoichiometry, and thermodynamics of this unique copper oxide. At moderate temperatures, equiaxed paramelaconite grains deposited with a strong out-of-plane texture; at lower temperatures the paramelaconite grains showed no texture but were columnar in geometry. X-ray photoelectron spectroscopy showed that the as-deposited Cu4O3 had a nonstoichiometric Cu:O ratio of 1.7:1; the ratio of Cu+ to Cu2+ was 1.8:1. On heating, this phase decomposed into CuO and Cu2O at temperatures ranging from 400 to 530 °C. Using differential scanning calorimetry, the heat of formation and Gibbs free energy for Cu4O3 were estimated to be −453 and −279 kJ/mol, respectively. On the basis of these calculations and our observations, we confirmed that Cu4O3 is a metastable phase.

Time-resolved x-ray microdiffraction studies of phase transformations during rapidly propagating reactions in Al/Ni and Zr/Ni multilayer foils

2010 ◽  
Vol 107 (11) ◽  
pp. 113511 ◽  
Author(s):  
J. C. Trenkle ◽  
L. J. Koerner ◽  
M. W. Tate ◽  
Noël Walker ◽  
S. M. Gruner ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Time Resolved ◽  
X Ray ◽  
Multilayer Foils

Microstructure Evolution and Properties of 7A56 Aluminum Alloy by Homogenization

2017 ◽  
Vol 898 ◽  
pp. 153-158 ◽  
Author(s):  
Da Xu ◽  
Zhi Hui Li ◽  
Guo Jun Wang ◽  
Long Bing Jin ◽  
Hong Wei Yan ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Microstructure Evolution ◽  
Equilibrium Phase ◽  
Hardness Test ◽  
Homogenization Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Second Phases ◽  
Al Matrix

The microstructure evolution and properties of Al-matrix in homogenized 7A56 alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), electrical conductivity and hardness test. The second phases in as-cast 7A56 alloy consisted of AlZnMgCu, Al2Cu and Al7Cu2Fe. With the homogenization temperature increasing, more non-equilibrium phase AlZnMgCu was dissolved into Al-matrix. The diffusion of alloying elements from AlZnMgCu phase into Al-matrix leads to a decrease of electrical conductivity and an increase of hardness. The lattice constant of α-Al has an increases of 0.0019 Å, 0.0032 Å and 0.0053 Å after 380°C/24h,430°C/24h,and 470°C/24 h treatment,respectively.

scholarly journals Collimated Magnetron Sputter Deposition for Mirror Coatings

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Anette Vickery ◽  
Carsten P. Jensen ◽  
Finn E. Christensen ◽  
Mads Peter Steenstrup ◽  
Troels Schønfeldt
Keyword(s):  
Magnetron Sputtering ◽  
Experimental Evidence ◽  
Sputter Deposition ◽  
X Ray ◽  
National Space ◽  
Planar Magnetron ◽  
Different Types ◽  
Magnetron Sputter Deposition ◽  
Magnetron Sputter ◽  
Present Experimental Evidence

At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence that a collimation of the sputtered particles is an efficient way to suppress the interfacial roughness of the produced multilayer. We present two different types of collimation optimized for the production of low roughness curved mirrors and flat mirrors, respectively.

Exothermic reactions in cold-rolled Ni/Al reactive multilayer foils

2008 ◽  
Vol 23 (2) ◽  
pp. 367-375 ◽  
Author(s):  
X. Qiu ◽  
J. Graeter ◽  
L. Kecskes ◽  
J. Wang
Keyword(s):  
Phase Evolution ◽  
Reaction Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Exothermic Reactions ◽  
X Ray ◽  
Multilayer Foils ◽  
Cold Rolled ◽  
Two Peaks ◽  
Evolution Sequence

Exothermic reactions in cold-rolled Ni/Al reactive multilayer foils were investigated in this study. A two-stage reaction process was observed in the self-propagating reactions in the cold-rolled foils that were ignited by a point-source flame. Foils taken out of the flame after completing the first stage of the reaction process were compared to those allowed to complete both stages. Differences in the phase-evolution sequence from the two types of foils were studied by differential scanning calorimetry (DSC), using slow and controlled heating of the samples. Several exothermic peaks could be identified from the DSC thermograms for both types of foils. Using the DSC, both the as-cold-rolled and partially reacted foils were heated to each peak temperature to identify the reaction product associated with each peak. X-ray diffraction and scanning electron microscopy analyses showed that the first two peaks corresponded to the formation of Al3Ni, while the third peak corresponded to the formation of AlNi.

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