scholarly journals Effect of He-appm/DPA ratio on the damage microstructure of tungsten

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2893-2899 ◽  
Author(s):  
R.W. Harrison ◽  
H. Amari ◽  
G. Greaves ◽  
J.A. Hinks ◽  
S.E. Donnelly
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Dislocation Loops ◽  
Vacancy Clusters ◽  
Transmission Electron ◽  
Damage Structure ◽  
Ordered Array ◽  
20 Nm

AbstractIn-situ ion irradiation and transmission electron microscopy has been used to examine the effects of the He appm to DPA ratio, temperature and dose on the damage structure of tungsten (W). Irradiations were performed with 15 or 60 keV He+ ions, achieving He-appm/displacements per atom (DPA) ratios of ∼40,000 and ∼2000, respectively, at temperatures between 500 and 1000°C to a dose of ∼3 DPA. A high number of small dislocation loops with sizes around 5–20 nm and a He bubble lattice were observed for both He-appm/DPA ratios at 500°C with a bubble size ∼1.5 nm. Using the g.b=0 criterion the loops were characterised as b = ±1/2<111> type. At 750°C bubbles do not form an ordered array and are larger in size compared to the irradiations at 500°C, with a diameter of ∼3 nm. Fewer dislocation loops were observed at this temperature and were also characterised to be b = ±1/2<111> type. At 1000°C, no dislocation loops were observed and bubbles grew as a function of fluence attributed to vacancy mobility being higher and vacancy clusters becoming mobile.

scholarly journals Direct Characterization of the Relation between the Mechanical Response and Microstructure Evolution in Aluminum by Transmission Electron Microscopy In Situ Straining

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1431
Author(s):  
Seiichiro Ii ◽  
Takero Enami ◽  
Takahito Ohmura ◽  
Sadahiro Tsurekawa
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Beam ◽  
Elastic Behavior ◽  
Annealed Specimen ◽  
Displacement Curve ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Stress Drops

Transmission electron microscopy in situ straining experiments of Al single crystals with different initial lattice defect densities have been performed. The as-focused ion beam (FIB)-processed pillar sample contained a high density of prismatic dislocation loops with the <111> Burgers vector, while the post-annealed specimen had an almost defect-free microstructure. In both specimens, plastic deformation occurred with repetitive stress drops (∆σ). The stress drops were accompanied by certain dislocation motions, suggesting the dislocation avalanche phenomenon. ∆σ for the as-FIB Al pillar sample was smaller than that for the post-annealed Al sample. This can be considered to be because of the interaction of gliding dislocations with immobile prismatic dislocation loops introduced by the FIB. The reloading process after stress reduction was dominated by elastic behavior because the slope of the load–displacement curve for reloading was close to the Young’s modulus of Al. Microplasticity was observed during the load-recovery process, suggesting that microyielding and a dislocation avalanche repeatedly occurred, leading to intermittent plasticity as an elementary step of macroplastic deformation.

scholarly journals Recent Development in In-situ Ion Irradiation Transmission Electron Microscopy

2013 ◽  
Vol 19 (S2) ◽  
pp. 438-439
Author(s):  
K. Hattar ◽  
S.M. Hoppe ◽  
C. Chisholm ◽  
O.J. El-Atwani ◽  
B.A. Hernandez-Sanchez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Transmission Electron

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

A freeze-fracture study of the cuticle of adult Nippostrongylus brasiliensis (Nematoda)

Parasitology ◽  
1993 ◽  
Vol 107 (5) ◽  
pp. 545-552 ◽  
Author(s):  
D. L. Lee ◽  
K. A. Wright ◽  
R. R. Shivers
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Freeze Fracture ◽  
Surface Coat ◽  
Nippostrongylus Brasiliensis ◽  
Freeze Fracturing ◽  
Transmission Electron ◽  
Fracture Study ◽  
20 Nm

SUMMARYThe surface of the cuticle of adult Nippostrongylus brasiliensis has been studied by means of the freeze-fracture technique and by transmission electron microscopy. Some of the surface coat appears to have been shed from the surface of the cuticle of adults fixed in situ in the intestine of its host and from the surface of individuals removed from the intestine and freeze-fractured. Freeze-fracturing the cuticle of individuals removed from the host has shown that this surface coat varies in thickness from 30 to 90 nm. The epicuticle is about 20 nm thick and cleaves readily to expose E- and P-faces. The P-face of the epicuticle possesses a small number of particles, similar to intra-membranous particles, whilst the E-face possesses a few, widely scattered depressions. Despite the presence of these particles the epicuticle is not considered to be a true membrane. Freeze-fracturing the remainder of the cuticle has confirmed its structure as described by conventional transmission electron microscopy. Clusters of particles on the P-face of the outer epidermal (hypodermal) membrane and corresponding depressions on the E-face of the membrane are thought to be associated with points of attachment of the cuticle to the epidermis (hypodermis). No differences in appearance of the cuticle and its surface layers were observed in individuals taken from 7-, 10-, 13- and 15-day infections.

Ion Beam-Induced Amorphization of (Mg, Fe)2SiO4 Olivine Series: An In Situ Transmission Electron Microscopy Study

1991 ◽  
Vol 235 ◽  
Author(s):  
L. M. Wang ◽  
R. C. Ewing
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Computer Modelling ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Resolution Electron Microscopy ◽  
Bond Ionicity ◽  
Transmission Electron

ABSTRACTEffects of ion beam irradiation of five members of the (Mg, Fe)2SiO4 olivine series, from synthetic pure fayalite (Fe2SiO4) to naturally occurring (Mg0.88Fe0.12)2SiO4, have been studied by in situ transmission electron microscopy (TEM). Under 1.5 MeV Kr+ ion room temperature irradiations, all of the samples have been amorphized. The critical amorphization dose or the total collision energy loss required for amorphization increased rapidly with the increasing Mg:Fe ratio which coincides with an increasing melting temperature (bond strength) and an increasing average bond ionicity. A 400 keV He+ ion irradiation of (Mg0.88Fe0.12)2-SiO4, which mainly results in ionization energy loss in the sample, did not cause amorphization even at a much higher dose rate and a much higher final dose. This indicates nuclear interactions (collisions) are primarily responsible for ion beam induced amorphization. Also, high resolution electron microscopy (HREM) images of the defect structure at a low ion dose have been obtained and compared with the displacement cascade structure generated by computer modelling.

An in situ transmission electron microscopy study of sintering and redispersion phenomena over size-selected metal nanoparticles: environmental effects

2014 ◽  
Vol 16 (34) ◽  
pp. 18176-18184 ◽  
Author(s):  
Farzad Behafarid ◽  
Sudeep Pandey ◽  
Rosa E. Diaz ◽  
Eric A. Stach ◽  
Beatriz Roldan Cuenya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pt Nanoparticles ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Pure Oxygen ◽  
Pure Hydrogen ◽  
Transmission Electron ◽  
20 Nm

The thermal and chemical stability of micelle-synthesized size-selected Pt nanoparticles (NPs) supported on thin SiO2(20 nm) films was monitoredin situ viatransmission electron microscopy (TEM) under pure hydrogen and pure oxygen environments.

High Resolution Transmission Electron Microscopy of Defect Clusters in Aluminum During Electron and Ion Irradiation at Room Temperature

1996 ◽  
Vol 439 ◽  
Author(s):  
Kazuo Furuya ◽  
Min Piao ◽  
Nobuhiro Ishikawa ◽  
Tetsuya Saito
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Ion Irradiation ◽  
In Situ Observation ◽  
Dislocation Loops ◽  
Frank Loop ◽  
Planar Defects ◽  
Defect Clusters ◽  
Transmission Electron

AbstractDefect clusters in Al during electron and ion irradiation have been investigated using highresolution transmission electron microscopy (HRTEM). An ION/HVEM system which consists of a high-voltage TEM and ion implanters was used for in-situ observation of damage evolution under 1000 keV electrons and 15 keV He+ irradiation at room temperature. HRTEM of Al in [110] orientation showed many planar defects along { 111 } planes during electron irradiation, while a high density of small polyhedron-shaped cavities (He-bubbles) was observed in addition to the planar defects after He+ irradiation. Multi-slice image simulation of various models of dislocation loops indicated the planar defect as an interstitial-type Frank loop.

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