Nanocrystalline titanium-magnesium alloys through mechanical alloying

1990 ◽  
Vol 5 (9) ◽  
pp. 1880-1886 ◽  
Author(s):  
C. Suryanarayana ◽  
F. H. Froes
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Deformation ◽  
High Temperature Annealing ◽  
Metastable Solid Solution ◽  
Equilibrium Conditions ◽  
Nanocrystalline Titanium ◽  
Equilibrium Phases ◽  
Fcc Structure

The solid solubility of magnesium in titanium under equilibrium conditions is reported to be extremely small. Mechanical alloying of a mixture of titanium and magnesium powders resulted in the formation of nanocrystalline (10–15 nm in size) grains of Ti–Mg solid solution. This solid solution has a metastable fcc structure with a = 0.426 nm and contains about 3 wt.% (6 at.%) magnesium in it. It is suggested that the fcc structure has formed as a result of the heavy mechanical deformation of the hep structure introduced during milling. High temperature annealing of the metastable solid solution led to its decomposition forming the equilibrium phases, viz., elemental titanium and magnesium.

The Influence of Ni on the Microstructure of Co-Base ODS Alloys

2012 ◽  
Vol 535-537 ◽  
pp. 1011-1014 ◽  
Author(s):  
Lin Zhang ◽  
Xin Bo He ◽  
Ming Li Qin ◽  
Ye Liu ◽  
Xuan Hui Qu
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Mechanical Alloying ◽  
Cleavage Fracture ◽  
Fracture Strength ◽  
Volume Fraction ◽  
Secondary Phases ◽  
The Matrix ◽  
Ods Alloys ◽  
Low Volume

Co-based ODS alloys strengthened by γ΄ precipitates and nanosized oxides are promising high-temperature structural materials. Single solid solution of Al and W in the matrix can not be achieved after mechanical alloying, resulting in the formation of low volume fraction of γ΄ phase and several kinds of secondary phases. The addition of Ni promotes the precipitation of γ΄ phase and reduces the amount of secondary phases by the enlargement of the solid solution limit of Al and W within the matrix. In comparison with the lower fracture strength and cleavage fracture mode of the alloy without the addition of Ni, Ni-containing Co-base ODS alloys exhibit much higher fracture strength and obvious ductile facture mode.

scholarly journals Preparation and characterization of metastable solid solution Mg0.33Al0.66 and Mg0.33Al0.63Si0.03 obtained by mechanical alloying

2019 ◽  
Author(s):  
Hassen Jaafar ◽  
Mohieddine Abdellaoui
Keyword(s):  
Solid Solution ◽  
Fuel Cells ◽  
Mechanical Alloying ◽  
Good Yield ◽  
Solid Hydrogen ◽  
Laves Phase ◽  
Current Work ◽  
Metastable Solid Solution ◽  
Metastable Compounds

The use of mechanical alloying in this work leads to a solid solution Mg0.33Al0.66 instead of Laves phase MgAl2. Monosubstituted alloy Mg0.33Al0.63Si0.03 was obtained in good yield after 20 hours mechanical alloying with shock power of 6.5 W/g. Current work in progress aims to study the thermodynamic hydrogenation properties of these metastable compounds and explore different substitution for possible adaptation serving stabilized solid-Hydrogen as bulk reservoir in Fuel Cells or Ni-MH batteries.

Improvement of the oxidation resistance of TiC-coated carbon black by high-temperature annealing in N2

RSC Advances ◽  
2016 ◽  
Vol 6 (30) ◽  
pp. 25601-25604
Author(s):  
Jianke Ye ◽  
Ke Bao ◽  
Yan Wen ◽  
Jiangtao Li
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Carbon Black ◽  
Grain Growth ◽  
Oxidation Resistance ◽  
Carbon Oxidation ◽  
High Temperature Annealing ◽  
Coated Carbon

The annealing of TiC-coated carbon black in N2 at 1000–1300 °C resulted in formation of a TiCxNy solid solution and grain growth, which significantly increased the commencement and completion temperatures of carbon oxidation.

On the bcc, fcc, hcp, and amorphous polymorphs of Zr3Al

1993 ◽  
Vol 8 (2) ◽  
pp. 242-244 ◽  
Author(s):  
A.R. Yavari ◽  
S. Gialanella ◽  
T. Benameur ◽  
R.W. Cahn ◽  
B. Bochu
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
High Temperature ◽  
Volume Expansion ◽  
Room Temperature ◽  
Metastable Phase ◽  
Mechanical Grinding ◽  
Bcc Structure ◽  
Bcc Phase ◽  
Fcc Structure

Rapid solidification of the Zr3Al liquid alloy allows retention of the high temperature β–Zr solid solution with bcc structure. Mechanical grinding is shown to amorphize this metastable phase very easily. Calculations show that the retained bcc phase has a free energy above that of the amorphous phase. The density of bcc Zr3Al at room temperature is found to be 2% lower than that of its equilibrium L12-ordered fcc structure as determined from their respective lattice parameters. The bcc phase thus represents a 2% volume expansion with respect to the fcc structure.

scholarly journals Preparation and characterization of metastable solid solution Mg0.33Al0.66 and Mg0.33Al0.63Si0.03 obtained by mechanical alloying

2019 ◽  
Author(s):  
Hassen Jaafar ◽  
Mohieddine Abdellaoui
Keyword(s):  
Solid Solution ◽  
Fuel Cells ◽  
Mechanical Alloying ◽  
Good Yield ◽  
Solid Hydrogen ◽  
Laves Phase ◽  
Current Work ◽  
Metastable Solid Solution ◽  
Metastable Compounds

The use of mechanical alloying in this work leads to a solid solution Mg0.33Al0.66 instead of Laves phase MgAl2. Monosubstituted alloy Mg0.33Al0.63Si0.03 was obtained in good yield after 20 hours mechanical alloying with shock power of 6.5 W/g. Current work in progress aims to study the thermodynamic hydrogenation properties of these metastable compounds and explore different substitution for possible adaptation serving stabilized solid-Hydrogen as bulk reservoir in Fuel Cells or Ni-MH batteries.

High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite

1996 ◽  
Vol 54 ◽  
pp. 374-375
Author(s):  
M. Larsen ◽  
R.G. Rowe ◽  
D.W. Skelly
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Aircraft Engine ◽  
Lattice Parameter ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Cross Sectional ◽  
Bcc Structure

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.

Defect reduction in oxygen implanted silicon-on-insulator material during high-temperature annealing

1989 ◽  
Vol 47 ◽  
pp. 604-605
Author(s):  
P. Roitman ◽  
B. Cordts ◽  
S. Visitserngtrakul ◽  
S.J. Krause
Keyword(s):  
High Temperature ◽  
Annealing Temperature ◽  
Silicon On Insulator ◽  
High Dose ◽  
High Temperature Annealing ◽  
High Current ◽  
Defect Reduction ◽  
Annealing Step ◽  
Multiple Cycle ◽  
Defect Densities

Synthesis of a thin, buried dielectric layer to form a silicon-on-insulator (SOI) material by high dose oxygen implantation (SIMOX – Separation by IMplanted Oxygen) is becoming an important technology due to the advent of high current (200 mA) oxygen implanters. Recently, reductions in defect densities from 109 cm−2 down to 107 cm−2 or less have been reported. They were achieved with a final high temperature annealing step (1300°C – 1400°C) in conjunction with: a) high temperature implantation or; b) channeling implantation or; c) multiple cycle implantation. However, the processes and conditions for reduction and elimination of precipitates and defects during high temperature annealing are not well understood. In this work we have studied the effect of annealing temperature on defect and precipitate reduction for SIMOX samples which were processed first with high temperature, high current implantation followed by high temperature annealing.

Sign in / Sign up

Export Citation Format

Share Document