Comparison of the Thermal Stabilities of Amorphous Hydrides Formed by Zr-Based Metallic Glasses

1986 ◽  
Vol 80 ◽  
Author(s):  
J. S. Cantrell ◽  
R. C. Bowman
Keyword(s):  
Metallic Glasses ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
X Ray ◽  
Decomposition Reactions ◽  
Free Metal ◽  
Metal Ratios ◽  
Approach Unity

AbstractDifferential scanning calorimetry (DSC) and x-ray diffraction (XRD) measurements were performed on a-Zr2 PdHx, a-Zr3 RhHx, a-Zr76 Fe24 Hx, and a- Zr2NiHx to assess the effects of hydrogen on their thermal stabilities. Only exothermic DSC peaks were observed for the hydrogen-free glasses and are shown to correspond to the formation of crystalline intermetallic phases. On the other hand, heating of the amorphous hydrides gives decomposition reactions with the generation of ZrHx (1.5 <x < 2.0) and either free metal (e.g., Rh) or a Zr-depleted intermetallic (e.g., ZrPd). With the exception of the Zr2 PdHx samples, hydrogenation significantly decreases the thermal stabilities (i.e., the exothermic transitions occur at lower temperatures in the amorphous hydrides). Endothermic peaks, which are associated with hydrogen evolution from the glass, are observed when the hydrogen-to-metal ratios approach unity.

Ti Microalloying Effect on Corrosion Resistance and Thermal Stability of Cu45Zr48Al7 Bulk Metallic Glass

2012 ◽  
Vol 490-495 ◽  
pp. 3868-3873 ◽  
Author(s):  
Xiao Hong Yang ◽  
Xi Peng Nie ◽  
Jian Zhong Jiang
Keyword(s):  
Thermal Stability ◽  
Corrosion Resistance ◽  
Metallic Glasses ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Glass Forming ◽  
Ti Addition ◽  
Mould Casting ◽  
Thermal Stability Of

Bulk metallic glasses (BMGs) of Cu45Zr48-xAl7Tix with x= 0, 1.5, and 3 at.% were prepared by copper mould casting. The corrosion resistance of the BMGs with different Ti contents was examined by potentiodynamic polarization tests and weight loss measurements in 1 N NaOH, 1 N H2SO4, 1 N H2SO4 + 0.01 N NaCl and 0.5 N NaCl solutions, respectively. The newly-developed BMGs’ corrosion resistance in Cl-- or both H+ and Cl--ions containing solutions can be greatly enhanced. The influence of Ti addition on glass forming ability (GFA) and thermal stability was investigated by x-ray diffraction and differential scanning calorimetry in detail. The alloy containing 1.5 at.% Ti exhibits the largest GFA, the critical size comes up to 10 mm in diameter.

scholarly journals Solvate Formation of Bis(demethoxy)curcumin: Screening and Characterization

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 407 ◽  
Author(s):  
Lina Yuan ◽  
Heike Lorenz
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Mass Loss ◽  
Storage Conditions ◽  
Stoichiometric Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
X Ray ◽  
Ambient Storage

Solvate formation of bis(demethoxy)curcumin (BDMC) was screened. Six solvates were obtained out of the nineteen solvents investigated. In the present work, three solvates, i.e., BDMC-tetrahydrofuran (THF), BDMC-1,4-dioxane (DIO) and BDMC-dimethyl sulfoxide (DMSO), were thoroughly studied. Their desolvation processes were characterized by temperature-resolved powder X-ray diffraction (TR-PXRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and hot-stage microscopy (HSM). TR-PXRD shows that all the solvates desolvate as the mother BDMC form and no new polymorph could be obtained. The stoichiometric ratio of solvates was calculated via the mass loss of solvents determined by TGA. The thermal stabilities of the solvates were obtained from DSC data and followed the order: BDMC-DMSO > -THF > -DIO. Moreover, stability performances at ambient storage conditions recorded by PXRD show that BDMC-DMSO was stable over three months.

Thermal Stability and Phase Transformation in Hfl-xCux Metallic Glasses

1985 ◽  
Vol 58 ◽  
Author(s):  
R. Schulz ◽  
N. L. Leem ◽  
B. M. Clemens
Keyword(s):  
Phase Transformation ◽  
Metallic Glasses ◽  
Phase Segregation ◽  
Anomalous Behavior ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ductile To Brittle Transition ◽  
The Difference ◽  
Structurally Stable

ABSTRACTIn this paper we report the difference in the structures, physical properties and thermal behaviors of two compositions of amorphous Hf-Cu. One (Hf50CU50) is near the eutectic composition and the other (Hf67Cu33) corresponds to an intermetallic compound. Transmission and scanning electron microscopy (TEM, SEM), differential scanning calorimetry (DSC), electrical resistivity and high-angle X-ray diffraction have been used to study these glasses in detail. Amorphous Hf67 Cu33 is structurally stable up to the crystallization temperature, while Hf50 Cu50 undergoes a ductile to brittle transition associated with a chemicai phase segregation at temperatures far below the glass transition. An anomalous behavior in the resistivity is associated with this phase transformation.

Investigation of Structure and Properties of the Al–Y–Ni–Co–Cu Metallic Glasses

2002 ◽  
Vol 17 (5) ◽  
pp. 1014-1018 ◽  
Author(s):  
Dmitri V. Louzguine ◽  
Akihisa Inoue
Keyword(s):  
Electron Microscopy ◽  
Metallic Glasses ◽  
Crystallization Behavior ◽  
Supercooled Liquid ◽  
Partial Replacement ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

The present paper reports the effect of partial replacement of Ni by Cu in the Al85Y8Ni5Co2 alloy. The studied alloys were produced by rapid solidification. Glass-formation, crystallization behavior, and stability of the supercooled liquid were studied by x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Partial replacement of Ni by Cu in the Al85Y8Ni5Co2 metallic glass caused formation of the nanoscale α–Al particles and resulted in a decrease in the crystallization temperature and disappearance of the supercooled liquid.

Crystallization of Zr-Ni metallic glasses

1988 ◽  
Vol 46 ◽  
pp. 456-457
Author(s):  
C. G. McKamey ◽  
D. M. Kroeger ◽  
D. S. Easton ◽  
J. A. Horton
Keyword(s):  
Metallic Glasses ◽  
Crystallization Process ◽  
Metastable Phase ◽  
Stoichiometric Composition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Short Range Ordering ◽  
Equilibrium Phases ◽  
Reported Data

In a previous paper the results of a study of the crystallization of Zr-Ni metallic glasses of compositions between 55 and 70 at. % Zr were reported. Data from differential scanning calorimetry (DSC) and x-ray diffraction (XRD) were presented and discussed with respect to the phase transformations occurring during the crystallization process. A metastable crystalline phase, shown by DSC and XRD results to appear between 57 and 63.2 at. % Zr, was the first phase to appear upon heating the amorphous metal. (Evidence indicates the stoichiometric composition for this phase is approximately 60% Zr.) This metastable phase transforms to the equilibrium crystalline phases (ZrNi and Zr2Ni) upon further heating. For compositions of 55-57 and 63.5-70% Zr only the equilibrium phases appear upon heating. It was noted that phase separation and chemical short range ordering (SRO) are believed to play an important role in the crystallization of these alloys.

scholarly journals Crystallization Process and Microstructural Evolution of Melt Spun Al-RE-Ni-(Cu) Ribbons

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 443
Author(s):  
Francisco G. Cuevas ◽  
Sergio Lozano-Perez ◽  
Rosa María Aranda ◽  
Raquel Astacio
Keyword(s):  
Crystallization Process ◽  
Primary Crystallization ◽  
Amorphous Structure ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
The Stability

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by differential scanning calorimetry, with Ce alloys being the most stable. The effect of Cu to reduce the nanocrystal size during primary crystallization was analyzed by transmission electron microscopy. This latter technique and x-ray diffraction showed the formation of intermetallic phases at higher temperatures. A clear difference was observed for the Ce alloy, with a simpler sequence involving the presence of Al3Ni and Al11Ce3. However, for the Y and Sm alloys, a more complex evolution involving metastable ternary phases before Al19RE5Ni3 appears, takes place. The shape of the intermetallics changes from equiaxial in the Ce alloys to elongate for Y and Sm, with longer particles for Sm and, in general, when Cu is added to the alloy.

The Microstructural Evolution of AA6111 Aluminum Alloy during Homogenization Treatment

2013 ◽  
Vol 749 ◽  
pp. 223-228 ◽  
Author(s):  
Shi Jiao Zhang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Xi Wu Li ◽  
Feng Wang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Intermetallic Phases ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Homogenization Treatment ◽  
X Ray ◽  
Transmission Electron ◽  
Eutectic Morphology ◽  
Scanning Electron

The microstructures of AA6111 automotive aluminum alloy were investigated by optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). The results indicated that as-cast AA6111 alloy has a complex microstructure. There were many kinds of intermetallic phases, such as lath-shaped β-Al5FeSi, Al15(FeMn)3Si2and Mg2Si on the grain boundaries. The Al5Cu2Mg8Si6precipitates presented non-equilibrium eutectic morphology in the grain interiors. After homogenization treatment (6h at 470), the low melting point Mg2Si phase began dissolving. The eutectic Al5Cu2Mg8Si6phase were dissolved completely after 530/24h homogenization treatment. The Al15(FeMn)3Si2phase started to be spheroidized at 560. Increasing treatment temperature will promote Mn to substitute for Fe in this phase.

Plasticity of bulk metallic glasses improved by controlling the solidification condition

2008 ◽  
Vol 23 (4) ◽  
pp. 941-948 ◽  
Author(s):  
Z.W. Zhu ◽  
S.J. Zheng ◽  
H.F. Zhang ◽  
B.Z. Ding ◽  
Z.Q. Hu ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
High Energy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Solidification Condition ◽  
X Ray ◽  
Transmission Electron ◽  
Injection Casting

Different bulk metallic glasses (BMGs) were prepared in ductile Cu47.5Zr47.5Al5, Zr62Cu15.4Ni12.6Al10, and brittle Zr55Ni5Al10Cu30 alloys by controlling solidification conditions. The achieved microstructures were characterized by x-ray diffraction, differential scanning calorimetry, transmission electron microscopy, and synchrotron- based high-energy x-ray diffraction. Monolithic BMGs obtained by high-temperature injection casting are brittle, while BMGs bearing some nanocrystals with the size of 3 to 7 nm and 2 to 4 nm, obtained by low-temperature injection casting and in situ suction casting, respectively, exhibit good plasticity. It indicates that the microstructures of BMGs are closely affected by the solidification conditions. Controlling the solidification conditions could improve the plasticity of BMGs.

Reversible Structural Relaxation in Fe-Ni-B-Si Metallic Glasses

1986 ◽  
Vol 80 ◽  
Author(s):  
R. Brüning ◽  
Z. Altounian ◽  
J. O. Ström-Olsen
Keyword(s):  
Metallic Glasses ◽  
Structural Relaxation ◽  
Short Range ◽  
Short Range Order ◽  
Composition Dependence ◽  
Published Data ◽  
Surface Crystallization ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

AbstractReversible structural relaxation has been studied in (Fe1-xNix)80B10Si10 by differential scanning calorimetry and X-ray diffraction. It is found that surface crystallization plays a major role in inhibiting reversibility. In consequence previously published data have presented a misleading picture about the composition dependence of the reversible effect in Fe-Ni-B-Si, which simply increases monotonically with Ni composition. There is no evidence that chemical short range order plays any role in reversibility.

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