Formation of metastable phases in Zr-ion-irradiated Al2O3 upon thermal annealing

2017 ◽  
Vol 66 (6) ◽  
pp. 388-396
Author(s):  
Naomasa Oka ◽  
Manabu Ishimaru ◽  
Masakazu Tane ◽  
Younes Sina ◽  
Carl J McHargue ◽  
...  
1981 ◽  
Vol 7 ◽  
Author(s):  
Bai-Xin Liu ◽  
Leszek S. Wieluniski ◽  
Martti MÄenpÄÄ ◽  
Marc-A. Nicolet ◽  
S. S. Lau

ABSTRACTAmorphous and three metastable crystalline phases have been formed in the Au-Si system by 300 keV Xe ion mixing using multilayered samples with average compositions of Au2Si8, AuSi, and Au7 Si3. Generally speaking, during the different stages of irradiation at liquid nitrogen temperature (LNT) or room temperature (R.T.), metastable crystalline phases are formed initially, and eventually an amorphous structure is obtained. Thermal decomposition of amorphous alloys yield different metastable crystalline phases. Some of the metastable crystalline phases can be formed directly from multilayered samples by steady-state thermal annealing. The formation mechanisms of metastable phases are discussed in terms of the processes involved in ion mixing and thermal annealing.


Author(s):  
Robert C. Rau ◽  
John Moteff

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.


Author(s):  
Matthew R. Libera

The liquid droplets produced by atomization processes are believed to undergo substantial supercooling during solidification, because the catalytic heterogeneities, for statistical reasons, tend to be isolated in the larger droplets. This supercooling can lead to the nucleation of metastable phases. As part of a study on the effect of liquid supercooling on nonequilibrium solidification, three binary Fe-Ni alloys have been produced by conventional argon atomization (Fe-20Ni, Fe-30Ni, and Fe-40Ni). The primary variables in these experiments are: i) the alloy composition; and ii) the powder particle diameter (inversely proportional to supercooling). Of particular interest in this system is the competitive nucleation kinetics between the stable fee and metastable bec phases. Bcc is expected to nucleate preferentially with decreasing %Ni and decreasing particle diameter.


1979 ◽  
Vol 40 (C2) ◽  
pp. C2-604-C2-607 ◽  
Author(s):  
Ch. Leibovitch ◽  
A. Rabinkin ◽  
M. Ron ◽  
E. Gartstein

2003 ◽  
Vol 27 (11) ◽  
pp. 1083-1086 ◽  
Author(s):  
H. Ito ◽  
T. Kusunoki ◽  
H. Saito ◽  
S. Ishio

Author(s):  
Satoshi Taniguchi ◽  
Norihiko Yamaguchi ◽  
Takao Miyajima ◽  
Masao Ikeda

2008 ◽  
Author(s):  
Gou XianFang ◽  
li xudong ◽  
xu ying ◽  
liang xinqing

2002 ◽  
Vol 716 ◽  
Author(s):  
G.Z. Pan ◽  
E.W. Chang ◽  
Y. Rahmat-Samii

AbstractWe comparatively studied the formation of ultra thin Co silicides, Co2Si, CoSi and CoSi2, with/without a Ti-capped and Ti-mediated layer by using rapid thermal annealing in a N2 ambient. Four-point-probe sheet resistance measurements and plan-view electron diffraction were used to characterize the silicides as well as the epitaxial characteristics of CoSi2 with Si. We found that the formation of the Co silicides and their existing duration are strongly influenced by the presence of a Ti-capped and Ti-mediated layer. A Ti-capped layer promotes significantly CoSi formation but suppresses Co2Si, and delays CoSi2, which advantageously increases the silicidation-processing window. A Ti-mediated layer acting as a diffusion barrier to the supply of Co suppresses the formation of both Co2Si and CoSi but energetically favors directly forming CoSi2. Plan-view electron diffraction studies indicated that both a Ti-capped and Ti-mediated layer could be used to form ultra thin epitaxial CoSi2 silicide.


2003 ◽  
Vol 766 ◽  
Author(s):  
Raymond N. Vrtis ◽  
Mark L. O'Neill ◽  
Jean L. Vincent ◽  
Aaron S. Lukas ◽  
Brian K. Peterson ◽  
...  

AbstractWe report on our work to develop a process for depositing nanoporous organosilicate (OSG) films via plasma enhanced chemical vapor deposition (PECVD). This approach entails codepositing an OSG material with a plasma polymerizable hydrocarbon, followed by thermal annealing of the material to remove the porogen, leaving an OSG matrix with nano-sized voids. The dielectric constant of the final film is controlled by varying the ratio of porogen precursor to OSG precursor in the delivery gas. Because of the need to maintain the mechanical strength of the final material, diethoxymethylsilane (DEMS) is utilized as the OSG precursor. Utilizing this route we are able to deposit films with a dielectric constant of 2.55 to 2.20 and hardness of 0.7 to 0.3 GPa, respectively.


Sign in / Sign up

Export Citation Format

Share Document