Detailed transmission electron microscopy study on the mechanism of dislocation loop rafting in tungsten

El-Atwani, O.
Aydogan, E.
Esquivel, E.
Efe, Mert
Wang, Y. Q.
Maloy, S. A.
Dislocation loop rafting and dislocation decoration have been previously observed in neutron and heavy ion irradiated materials. Understanding the fundamental aspects of these phenomena assist in evaluating irradiation damage of nuclear materials. Multiple different mechanisms have been suggested to explain loop rafting. Here, we performed a detailed transmission electron microscopy study on dislocation loop rafts in heavy ion irradiated tungsten. Different imaging conditions showed that the rafts are of Burgers vector type and specifically the same Burgers vector variant (1>) in the particular grain analyzed. Some rafts were associated with dislocation lines while some form as a result of alignment of dislocation loops. They were shown to form at both room temperature (RT) and high temperature with stronger rafts forming at RT. These observations confirm the mechanism previously suggested by Wen et al. which explains raft formation due to loop glide, cluster-cluster and grown-in dislocation cluster interaction with subsequent Burgers vector rotation. Similar irradiation studies on nanocrystal-line tungsten showed that these materials are more resistant to raft formation at RT irradiations. Published by Elsevier Ltd on behalf of Acta Materialia Inc.


Nano-scale phase separation in amorphous Fe-B alloys: Atomic and cluster ordering
AYKOL, Muratahan; Mehrabov, Amdulla; Akdeniz, Mahmut Vedat (Elsevier BV, 2009-01-01)
Nano-scale phase separation encountered in metallic glasses is investigated for amorphous Fe80B20 and Fe83B17 alloys in an interaction field calculated via electronic theory of alloys in pseudopotential approximation combined with MC equilibration and reverse MC simulation. The phenomenon is identified regarding three topological aspects: (1) pure Fe-clusters as large as similar to 0.9 nm and pure Fe-contours similar to 0.72 nm thick are found to exist; (2) Fe-rich highly deformed-bcc regions are observed; ...
In Situ Micro-Pillar Compression to Examine Radiation-Induced Hardening Mechanisms of FeCrAl Alloys
Cui, Yuchi; Aydoğan Güngör, Eda; Gigax, Jonathan G.; Wang, Yongqiang; Misra, Amit; Maloy, Stuart A.; Li, Nan (Elsevier BV, 2021-01-01)
© 2020The effects of 5 MeV Fe2+ ion irradiation at 300°C on the microstructure evolution and deformation behavior of a FeCrAl C26M alloy are presented. It has been found that dislocation loop density increases an order of magnitude from 1 dpa to 16 dpa irradiations, whereas, the dislocation loop size saturates with increasing damage. Micropillars, 600 nm in diameter and 1.3 µm in height, were fabricated and compressed inside grains with , and crystallographic orientations, respectively. {112} has been id...
Unprecedented irradiation resistance of nanocrystalline tungsten with equiaxed nanocrystalline grains to dislocation loop accumulation
El-Atwani, O.; Esquivel, E.; Aydoğan Güngör, Eda; Martinez, E.; Baldwin, J. K.; Li, M.; Uberuaga, B. P.; Maloy, S. A. (Elsevier BV, 2019-02-01)
Nanocrystalline metals are often postulated as irradiation tolerant materials due to higher grain boundary densities. The efficiency of these materials in mitigating irradiation damage is still under investigation. Here, we present an in-situ transmission electron microscopy with ion irradiation study on equiaxed 35 nm grained tungsten (NCW-35 nm) and compare its radiation tolerance, in terms of dislocation loop damage, to several other grades of tungsten with different grain sizes at two temperatures (RT a...
The effect of red phosphorus on the fire properties of intumescent pine wood flour - LDPE composites
Altun, Yasemin; DOĞAN, Mehmet; Bayramlı, Erdal (Wiley, 2016-08-01)
Red phosphorus (RP) was used to improve the fire performance of wood flour - low density polyethylene (LDPE) composites containing ammonium polyphosphate (APP). The fire performance of LDPE-based composites was investigated by using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis, and cone calorimeter. The addition of 30 wt% APP increased the LOI value from 17.5 to 24.2 and still burned to clamp (BC) in UL-94 test. The RP showed beneficial effect when combinedly used with APP. The ma...
Experimental investigation on chloroprene and acrylonitrile butadiene rubber types reinforced with nano-materials
Doğan, Özge; Esat, V.; Bal, B. (IOP Publishing, 2019-08-01)
In this research, the effects of three different nano-materials (Nano-Carbon Black, Nano-ZnO, and Multi-Walled Carbon Nanotubes (MWNTs)) on two different rubber types (Chloroprene Rubber (CR), and Acrylonitrile Butadiene Rubber (NBR)) were experimentally investigated. In order to achieve this purpose, mechanical tests and detailed aging tests (in air, oil and fuel) were conducted conforming to international standards. Three different nano-materials were added to rubber with different combinations. A good di...
Citation Formats
O. El-Atwani, E. Aydogan, E. Esquivel, M. Efe, Y. Q. Wang, and S. A. Maloy, “Detailed transmission electron microscopy study on the mechanism of dislocation loop rafting in tungsten,” ACTA MATERIALIA, pp. 277–283, 2018, Accessed: 00, 2020. [Online]. Available: