Are processing conditions similar in ball milling and high-pressure torsion? The case of the tetragonal-to-monoclinic phase transition in ZrO2 powders

2012 ◽  
Vol 67 (4) ◽  
pp. 340-343 ◽  
Author(s):  
Francesco Delogu
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Ball Milling ◽  
Monoclinic Phase ◽  
High Pressure Torsion ◽  
Processing Conditions

scholarly journals Microstructural Investigation of Nanocrystalline Hydrogen-Storing Mg-Titanate Nanotube Composites Processed by High-Pressure Torsion

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 563 ◽  
Author(s):  
Marcell Gajdics ◽  
Tony Spassov ◽  
Viktória Kovács Kis ◽  
Ferenc Béke ◽  
Zoltán Novák ◽  
...  
Keyword(s):  
High Pressure ◽  
Ball Milling ◽  
High Pressure Torsion ◽  
High Energy ◽  
Titanate Nanotubes ◽  
Microstructural Investigation ◽  
Microstructural Parameters ◽  
Preparation Conditions ◽  
Average Dislocation Density ◽  
Nanotube Composites

A high-energy ball milling and subsequent high-pressure torsion method was applied to synthesize nanocrystalline magnesium samples catalyzed by TiO2 or titanate nanotubes. The microstructure of the as-milled powders and the torqued bulk disks was characterized by X-ray diffraction. The recorded diffractograms have been evaluated by the convolutional multiple whole profile fitting algorithm, which provided microstructural parameters (average crystal size, crystallite size distribution, average dislocation density). The morphology of the nanotube-containing disks has been examined by high-resolution transmission electron microscopy. The effect of the different additives and preparation conditions on the hydrogen absorption behavior was investigated in a Sieverts’-type apparatus. It was found that the ball-milling route has a prominent effect on the dispersion and morphology of the titanate nanotubes, and the absorption capability of the Mg-based composite is highly dependent on these features.

scholarly journals New Mg–V–Cr BCC Alloys Synthesized by High-Pressure Torsion and Ball Milling

2018 ◽  
Vol 59 (5) ◽  
pp. 741-746 ◽  
Author(s):  
Keisuke Fujiwara ◽  
Ryoko Uehiro ◽  
Kaveh Edalati ◽  
Hai-Wen Li ◽  
Ricardo Floriano ◽  
...  
Keyword(s):  
High Pressure ◽  
Ball Milling ◽  
High Pressure Torsion

Processing Different Magnesium Alloys through HPT

2014 ◽  
Vol 783-786 ◽  
pp. 2617-2622 ◽  
Author(s):  
Livia Raquel C. Malheiros ◽  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Structure Refinement ◽  
Hardness Distribution ◽  
Metallic Materials ◽  
Processing Conditions ◽  
Significant Structure

High-Pressure Torsion (HPT) is widely used to refine the structure of metallic materials through the use of severe plastic deformation. This technique is used in this report to process different magnesium alloys using various processing conditions. The high hydrostatic pressure allows processing of these materials at room temperature without cracking. The structure was characterized and hardness distribution was determined at different areas of the processed samples. The results show significant structure refinement and increased hardness. The evolution of the structure and hardness depends on the alloying and HPT processing conditions.

Monoclinic phase of boron nitride appearing during the hexagonal cubic phase transition at high pressure and high temperature

1996 ◽  
Vol 68 (2) ◽  
pp. 182-184 ◽  
Author(s):  
Shigeo Horiuchi ◽  
Lian‐Long He ◽  
Mitsuko Onoda ◽  
Minoru Akaishi
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Temperature ◽  
Boron Nitride ◽  
Monoclinic Phase ◽  
Cubic Phase

Pressure-Induced Nano-Crystallization of Y2O3

2011 ◽  
Vol 1297 ◽  
Author(s):  
Stuart Deutsch ◽  
Jafar F. Al-Sharab ◽  
Bernard H. Kear ◽  
Stephen D. Tse
Keyword(s):  
Phase Transition ◽  
Grain Size ◽  
High Pressure ◽  
Phase Transformation ◽  
Monoclinic Phase ◽  
Transformation Process ◽  
Coarse Grained ◽  
Nanocrystalline State ◽  
Phase Transformation Process ◽  
Reversible Phase

ABSTRACTA reversible-phase transformation process to convert coarse-grained polycrystalline cubic-Y2O3 directly into the nanocrystalline state is being developed. The process involves a forward cubic-to-monoclinic phase transition under high pressure and a backward transformation from monoclinic-to-cubic under a lower pressure. The process has been used to reduce the grain size of fully dense cubic-Y2O3 from 300 μm to 0.1 μm. A surface modification effect, comprising a columnar-grained structure, has also been observed. Preliminary work indicates that the surface structure is modified, apparently formed by interaction between the graphite heater and sample.

Evidence of α → ω phase transition in titanium after high pressure torsion

2008 ◽  
Vol 99 (1) ◽  
pp. 36-41 ◽  
Author(s):  
Yulia Ivanisenko ◽  
Askar Kilmametov ◽  
Harald Rösner ◽  
Ruslan Z. Valiev
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Ω Phase

scholarly journals High Strength and Ductility in Ball-Milled Titanium Powders Consolidated by High-Pressure Torsion

2010 ◽  
Vol 654-656 ◽  
pp. 1239-1242 ◽  
Author(s):  
Kaveh Edalati ◽  
Z. Horita ◽  
Hiroshi Fujiwara ◽  
Kei Ameyama ◽  
Masaki Tanaka ◽  
...  
Keyword(s):  
High Pressure ◽  
Ball Milling ◽  
High Pressure Torsion ◽  
High Strength ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Titanium Powders ◽  
Strength And Ductility

Pure Ti powders were subjected to ball milling and subsequently high-pressure torsion (HPT) for consolidation. It is found that a fully dense (99.9%) disc with ultrafine grained structure (~50-300 nm) was produced. The strength and ductility were well comparable to those of ball-milled Ti-6%Al-4%V powders after hot roll sintering.

Effects of High Pressure on the Luminescent Properties of Nanocrystalline and Bulk Y2O3:Eu3+

2008 ◽  
Vol 8 (3) ◽  
pp. 1404-1409 ◽  
Author(s):  
X. Bai ◽  
H. W. Song ◽  
B. B. Liu ◽  
Y. Y. Hou ◽  
G. H. Pan ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Surface Energy ◽  
Relative Intensity ◽  
Monoclinic Phase ◽  
Local Environment ◽  
Luminescent Properties ◽  
Cubic Phase ◽  
Spectral Changes ◽  
20 Nm

High pressure-induced spectral changes in a 20-nm cubic nanocrystalline yttria doped with europium and its corresponding bulk were studied in the range of 550–750 nm, corresponding to the 5D0 → 7FJ (J = 0–4) transitions. The results demonstrate that the bulk Y2O3 underwent phase transition from the cubic phase to the monoclinic phase as the pressure increased to 15 GPa, while the 20-nm nanocrystals did not. This can be concluded from the fact that the 5D0 → 7F0 line and the three 5D0 → 7F1 sublines originating from the cubic phase disappeared, while another group of 5D0 → 7F0 and 5D0 → 7F1 lines appeared. In addition, the relative intensity of the peak around 630 nm to that around 611 nm varied obviously as the pressure surpassed 15 GPa. The variations in the nanocrystals were more sluggish in comparison to those in the bulk, indicating that the nanocrystalline yttria had improved compressibility, which is attributed to an increased surface energy in nanocrystals. The local environment surrounding luminescent Eu3+ in the nanocrystals and the bulk both became more disordered with the increase of the pressure. The phase transition from the cubic to the monoclinic is irreversible.

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