Amorphous Phase Formation and Heat Treating Evolution in Mechanically Alloyed Al-Ti Powders

2018 ◽  
Vol 772 ◽  
pp. 118-122
Author(s):  
Petr Urban ◽  
Eduardo Sanchez Caballero ◽  
Fatima Ternero ◽  
Francisco Javier Viña Reina ◽  
Francisco Gomez Cuevas
Keyword(s):  
Electron Microscopy ◽  
Microstructural Characterization ◽  
Heat Treating ◽  
High Energy ◽  
Amorphous Structure ◽  
Elemental Distribution ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Alloy Heat

This paper focuses on the microstructural characterization of Al25Ti75, Al37Ti63, Al50Ti50, Al63Ti37and Al75Ti25powders mixtures prepared by mechanical alloying (MA). The high-energy ball-milling, up to 75 h, of aluminium and titanium powders leads to a nanocrystalline or an amorphous structure. It is showed that a stable amorphous Al–Ti phase with uniform elemental distribution forms after 50 h of milling in Al50Ti50alloy. Heat treatment of the different alloys leads to the crystallization of AlTi3, AlTi, Al2Ti and Al3Ti intermetallic compounds. A comprehensive study by laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) was carried out on the structure, surface morphology and thermal behaviour of the MA Al-Ti mixtures, both of milled and heat treated powders.

scholarly journals Mechanically Alloyed Amorphous Ti50(Cu0.45Ni0.55)44–xAlxSi4B2 Alloys with Supercooled Liquid Region

2002 ◽  
Vol 17 (7) ◽  
pp. 1743-1749 ◽  
Author(s):  
L. C. Zhang ◽  
J. Xu ◽  
E. Ma
Keyword(s):  
Amorphous Alloys ◽  
Supercooled Liquid ◽  
High Energy ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Beneficial Effects ◽  
State Process ◽  
Transmission Electron

A high-energy ball milling procedure has been developed to produce amorphous alloys in Ti50(Cu0.45Ni0.55)44−xAlxSi4B2 (x= 0, 4, 8, 12) powder mixtures. The milling products were characterized using x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The Ti-based amorphous alloy powders prepared through this solid-state process exhibit a well-defined glass transition and a supercooled liquid region (ΔTx =64 K) close to the largest achieved so far for Ti-based undercooled melts. The substitution of Al for Cu and Ni has beneficial effects on stabilizing the supercooled liquid. Residual nanocrystals of the αTi structure are uniformly dispersed in the amorphous matrix. The composite alloy powders offer the potential for consolidation in the supercooled liquid region to bulk lightweight amorphous alloys and the possibility to attain desirable mechanical properties.

Atmosphere effects of the amorphization reaction in NiZr by ball milling

1993 ◽  
Vol 8 (2) ◽  
pp. 307-313 ◽  
Author(s):  
K. Aoki ◽  
A. Memezawa ◽  
T. Masumoto
Keyword(s):  
High Energy ◽  
Hydrogen Atmosphere ◽  
Nitrogen Atmosphere ◽  
Gas Absorption ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
High Energy Ball Mill ◽  
Energy Ball

An intermetallic compound c–NiZr and a mixture of elemental powders of nickel and zirconium [Ni50Zr50 (at. %)] have been mechanically ground (MG) and mechanically alloyed (MA), respectively, using a high-energy ball mill in various atmospheres. The products were characterized by x-ray diffraction, transmission electron microscopy, differential scanning calorimetry, and chemical analysis as a function of milling time. An amorphous a–NiZr alloy was prepared by both MG and MA in an argon atmosphere. By MG of NiZr, an amorphous nitride a–NiZrN0.15 was synthesized in a nitrogen atmosphere, while a crystalline hydride c–NiZrH3 was formed in a hydrogen atmosphere. On the other hand, ZrN and ZrH2 were formed by MA in a nitrogen and a hydrogen atmosphere, respectively. The amorphization reaction was observed between ZrH2 and Ni by further MA in a hydrogen atmosphere, and a mixture of a–NiZrxHy (x < 1) and ZrH2 was obtained. However, no amorphization was observed by MA between ZrN and Ni in a nitrogen atmosphere. The effects of the milling atmosphere on the phase formations during MG and MA are discussed based on the gas absorption rate.

Solid State Amorphization of Ti60Si40 Alloy via Mechanical Alloying

2021 ◽  
Vol 876 ◽  
pp. 7-12
Author(s):  
Petr Urban ◽  
Fátima Ternero Fernández ◽  
Rosa M. Aranda Louvier ◽  
Raquel Astacio López ◽  
Jesus Cintas Físico
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Mechanical Alloying ◽  
Amorphous Phase ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Heating Up

The effect of milling time on the microstructure evolution and formation of amorphous phase of Ti60Si40 alloy produced by mechanical alloying (MA) has been investigated. Laser diffraction, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) were employed to characterize the particle size, morphology and structure of mechanically alloyed Ti60Si40. When the milling time is increased to 20 h, the particle size decreases from 23.7 to 4.7 μm, the shape of the particles changes to spherical and the crystalline structure is transformed into an amorphous phase. The amorphous Ti60Si40 alloy is stable when heating up to 750oC. Above this temperature, the cold crystallization of the intermetallic compounds Ti5Si3 and/or Ti5Si4 begins.

Effect of Boron on the Amorphization of Fe-Si Alloys by Mechanical Alloying

2012 ◽  
Vol 730-732 ◽  
pp. 739-744 ◽  
Author(s):  
Petr Urban ◽  
Francisco Gomez Cuevas ◽  
Juan M. Montes ◽  
Jesus Cintas
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Alloy System ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural And Phase Transformations ◽  
Transmission Electron ◽  
Energy Ball

The amorphization process by mechanical alloying in the Fe-Si alloy system has been studied. High energy ball milling has been applied for alloys synthesis. X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to monitor the structural and phase transformations through the different stages of milling. The addition of amorphous boron in the milling process and the increase of the milling time were used to improve the formation of the amorphous phase. Heating the samples resulted in the crystallization of the synthesized amorphous alloys and the appearance of equilibrium intermetallic compounds.

Extending Energy-Filtered Transmission Electron Microscopy (EFTEM) into Three Dimensions Using Electron Tomography

2003 ◽  
Vol 9 (6) ◽  
pp. 542-555 ◽  
Author(s):  
Matthew Weyland ◽  
Paul A. Midgley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Tomography ◽  
Three Dimensional ◽  
High Energy ◽  
Three Dimensions ◽  
Series Data ◽  
Elemental Distribution ◽  
Transmission Electron

The length scales on which materials microstructures are being formed, grown, and even designed are becoming increasingly small and increasingly three-dimensional. For such complex structures two-dimensional transmission electron microscopy (TEM) analysis is often inadequate and occasionally misleading. One approach to this problem is the modification of electron tomography techniques, developed for structural biology, for use in materials science. Energy-Filtered (EF) TEM elemental distribution images approximate to true projections of structure, and, as such, can be used to reconstruct the three-dimensional distribution of chemical species. A sample holder has been modified to allow the high tilt (±60°) required for tomography and a semiautomatic acquisition script designed to manage energy-loss acquisition. Tilt series data sets have been acquired from two widely different experimental systems, Cr carbides in 316 stainless steel and magnetite nanocrystals in magnetotactic bacteria, demonstrating single- and multiple-element tomography. It is shown that both elemental maps and jump-ratio images are suitable for reconstruction, despite the effects of diffraction contrast in the former and thickness changes in the latter. It is concluded that the image contrast, signal, and signal-to-noise ratio (SNR) are key to the achievable reconstruction quality and, as such, the technique may be of limited value for high energy loss/small inelastic cross section edges.

Electrosynthesis and Microstructural Characterization of Anodic VOx Films

2000 ◽  
Vol 15 (7) ◽  
pp. 1483-1489 ◽  
Author(s):  
J. P. Schreckenbach ◽  
D. Butte ◽  
G. Marx ◽  
B. R. Johnson ◽  
W. M. Kriven
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Microstructural Characterization ◽  
Amorphous Structure ◽  
Vanadium Oxides ◽  
Electrolyte System ◽  
Transmission Electron ◽  
Nanocrystalline Phases ◽  
Acetate Electrolyte

Anodic conversion films of vanadium oxides on vanadium were potentiodynamically generated at high voltages in an acetate electrolyte system. The microstructure of the anodic VOx coatings was characterized by surface and solid-state techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. An amorphous structure is proposed in which network-forming [VO4] tetrahedra in various degrees of condensation are connected by distorted [VO5] and [VO6] units. Such polyhedra lead to the formation of nanocrystalline phases of stoichiometric and substoichiometric vanadium oxides, which were observed in the amorphous phase.

scholarly journals In-situ TEM annealing of amorphous Fe-24at.%W coatings and the effect of crystallization on hardness

2020 ◽  
Vol 56 (5) ◽  
pp. 4006-4012
Author(s):  
Antonio Mulone ◽  
Inga Ennen ◽  
Andreas Hütten ◽  
Uta Klement
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Structure ◽  
In Situ Tem ◽  
Amorphous Coating ◽  
Scanning Calorimetry ◽  
Plating Bath ◽  
Maximum Value ◽  
Transmission Electron

AbstractThis paper describes the crystallization which occurs upon annealing of an amorphous Fe-24at.%W coatings, electrodeposited from a glycolate-citrate plating bath. A combination of Differential Scanning Calorimetry and in-situ Transmission Electron Microscopy annealing is used to study the onset of crystallization of the amorphous coating. The in-situ TEM analyses reveal the formation of first crystallites after annealing at 400 °C for 30 min. Upon a temperature increase to 500–600 °C, the crystallites develop into Fe-rich nanocrystals with ~ 40 nm grain size. The nanocrystals are dispersed in the remaining amorphous Fe-W matrix, which results in the formation of a mixed nanocrystalline-amorphous structure. The observed crystallization can be held responsible for the increase in the hardness obtained upon annealing of Fe-24at.%W coatings. In fact, the hardness of the as-deposited material increases from 11 to 13 GPa after annealing at 400 °C, and it reaches the maximum value of 16.5 GPa after annealing at 600 °C.

scholarly journals Study on the Photodegradation Stability of Poly(butylene Succinate-co-butylene Adipate)/TiO2 Nanocomposites

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Lihai Cai ◽  
Zhiguo Qi ◽  
Jun Xu ◽  
Baohua Guo ◽  
Zhongyao Huang
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Chain Scission ◽  
High Energy ◽  
Mechanical Tests ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Transmission Electron ◽  
The Matrix ◽  
Ft Ir

A poly(butylene succinate-co-butylene adipate)/TiO2 (PBSA/TiO2) nanocomposite was prepared by a melt-blending process. The effect of TiO2 nanoparticles on the photodegradation behaviors of the nanocomposite was investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), rheological measurements, and mechanical tests. TEM images of the PBSA/TiO2 revealed that the TiO2 nanoparticles were well dispersed in the matrix without obvious aggregation. The FT-IR results indicated that the TiO2 nanoparticles can block high-energy ultraviolet (UV) light and reduce the degradation of the PBSA matrix. The viscosity analysis results indicated that the TiO2 nanoparticles inhibited the chain scission of PBSA matrix under irradiation. In addition, the surface of the PBSA/TiO2 films and their mechanical properties change less than that of untreated PBSA films during the photoaging process. The obtained results imply that the TiO2 nanoparticles can be considered as an efficient photodegradation-resistant additive to PBSA for reducing photodegradation.

Two-dimensional titanium carbide (Ti3C2) MXene towards enhancing thermal catalysis decomposition of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50)

2020 ◽  
Vol 98 (11) ◽  
pp. 697-700
Author(s):  
Shuaida Zhu ◽  
Yuqi Feng ◽  
Xiaoxia Li ◽  
Zhaobian Xie ◽  
Haixia Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Catalytic Mechanism ◽  
High Energy ◽  
High Energy Density ◽  
Two Dimensional ◽  
Scanning Calorimetry ◽  
Reaction Heat ◽  
Transmission Electron ◽  
Catalytic Role

In this study, we demonstrated that two-dimensional (2D) MXene materials (Ti3C2) were creatively introduced into the thermal catalysis fields of high energy density salts dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and Ti3C2 MXene materials play a significant catalytic role in the thermal decomposition of TKX-50. Scanning electron microscopy, X-ray diffraction, and transmission electron microscopy were used to characterize the morphology and structure of the Ti3C2 MXene nanosheets. Differential scanning calorimetry was used to evaluate the thermal decomposition properties of pure TKX-50 with and without 2D Ti3C2 added. The results showed that with adding 5 wt% MXene, the peak temperature of TKX-50 was reduced from 250.5 to 233.3 °C, which is a reduction of 17.2 °C. The reaction heat release increased from 2197 to 2907 J g−1, which is an increase of 710 J g−1. The Ea was decreased by 44.8 kJ mol−1, from 220.0 to 175.2 kJ mol−1. Moreover, a synergistic catalytic mechanism for the thermal decomposition of TKX-50 was proposed.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

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