Crystal Growth: Substructure and Recrystallization

Glebovsky, V.G.

doi:10.5772/34871

Cited by 12 publications

(34 citation statements)

References 52 publications

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“…Generally, single crystals of refractory metals with bcc-lattice prepared using these techniques are characterized by a specific dislocation substructure with the size of subgrains, which can be divided into three orders of magnitude. [1,4,9,[11][12] The more developed substructure is typical for crystals prepared by plasma-arc melting in comparison with EBFZM. The formation of dislocations and substructure of single crystals grown from the melt depends on the axial and radial thermal stresses during growing and cooling of single crystals, the impurity and alloying elements concentration gradients in the solid phase, the lattice supersaturation with vacancies, the substructure inheritance of the seed crystal into the growing crystal, etc.…”

Section: Resultsmentioning

confidence: 99%

“…The formation of dislocations and substructure of single crystals grown from the melt depends on the axial and radial thermal stresses during growing and cooling of single crystals, the impurity and alloying elements concentration gradients in the solid phase, the lattice supersaturation with vacancies, the substructure inheritance of the seed crystal into the growing crystal, etc. [4] The dislocation density of these single crystals was about 10 5 -10 6 cm À2 , in case of plasma-arc melting up to 10 8 cm À2 . [1,4,9] At investigation of macrostructure of single crystals of tungsten and molybdenum on the surface of the crystals, alternating light and dark strips were observed as a result of various etching of edges ( Figure 2).…”

Section: Resultsmentioning

confidence: 99%

“…[4] The dislocation density of these single crystals was about 10 5 -10 6 cm À2 , in case of plasma-arc melting up to 10 8 cm À2 . [1,4,9] At investigation of macrostructure of single crystals of tungsten and molybdenum on the surface of the crystals, alternating light and dark strips were observed as a result of various etching of edges ( Figure 2). Some sub-grain boundaries of the 1st order were also observed without any additional magnification aids (visually), which indicates their relatively high disorientation.…”

Section: Resultsmentioning

confidence: 99%

“…We consider such ingots as poly-crystalline samples with preferred crystallographic orientations. [1,4] Laue patterns taken from the samples of single crystals of tungsten-based alloys are shown in Figure 6 and 7.…”

Section: Resultsmentioning

confidence: 99%

“…The principle of this method is described in detail in ref. [1,[3][4][5][6][7] . The method of plasma-arc melting, developed in the Baikov Institute of Metallurgy and Materials Science of Russian Academy of Sciences (BIMMS RAS), [1,12] ensured obtaining of single crystals of alloys of sufficiently large size, which allowed us to expand the scope of their practical application.…”

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Preparation and Investigation of Structural Parameters of Single Crystals of Low‐Alloyed Alloys on the Base of Tungsten and Molybdenum

et al. 2013

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Lower structural perfection of W‐Ta single crystals is associated with considerable disturbance of the melt by plasma arc, great temperature gradients and cooling rate of the growing single crystal due to “air rinsing” of its surface by plasma‐forming gas. In the peripheral areas of this sample a large number of small sub‐grains is presented, which confirms the trend towards fragmentation of the structure at crystallization from the beginning to the end of the ingot.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Preparation and Investigation of Structural Parameters of Single Crystals of Low‐Alloyed Alloys on the Base of Tungsten and Molybdenum

et al. 2013

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Vacancy cluster growth and thermal recovery in hydrogen-irradiated tungsten

Zibrov

Egger

Heikinheimo

et al. 2020

Journal of Nuclear Materials

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The thermal evolution of vacancies and vacancy clusters in tungsten (W) has been studied. W (100) single crystals were irradiated with 200 keV hydrogen (H) ions to a low damage level (5.8 × 10 −3 dpa) at 290 K and then annealed at temperatures in the range of 500-1800 K. The resulting defects were characterized by positron annihilation lifetime spectroscopy (PALS) and positron annihilation Doppler broadening spectroscopy (DBS). Annealing at 700 K resulted in the formation of clusters containing 10-15 vacancies, while at 800 K and higher temperatures clusters containing about 20 vacancies or more were formed. Reduction of the defect concentration likely accompanied by further coarsening of the clusters started at 1300 K and ended at 1800 K with the complete defect recovery. The determined cluster sizes at 700 K and 800 K were larger than the estimated minimum cluster sizes that are thermally stable at these temperatures, indicating that the migration and ensuing coalescence of small clusters plays an important role in cluster growth.

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Nanoindentation Size Effect of Tungsten Single Crystal

Zhou

Gao

Zhang

et al. 2017

Rare Metal Materials and Engineering

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The load-displacement curves, elastic modulus, indent morphology, nanohardness and elastic recovery of high purity tungsten single crystal were investigated by nanoindentation and scanning probe microscopy. Results show that W (111) crystal plane undergoes elastic deformation and plastic deformation during the loading-unloading process, and the load-displacement curve does not show discontinuity, which demonstrates that cracks and brittle fracture are not formed in the indents. Moreover, the pileup behavior around indents reveals that tungsten single crystal has a low work hardening tend. The nanohardness and elastic modulus of tungsten single crystal were measured by continuous stiffness measurement (CSM), and a size effect on the nanohardness and elastic modulus of tungsten single crystal was observed, which decrease with the increase of indentation depth. The Nix-Gao model was employed to analyze the nanoindentation mechanical characteristics of tungsten single crystals, and the characteristic length (h *), the intrinsic hardness in the limit of infinite depth (H0) and size effect index (m) were calculated to be 1490 nm, 6.79 GPa and 0.18, respectively, which indicates that tungsten single crystal has a significant size effect when the indentation depth is below 1490 nm, and the size effect becomes more insignificant when indentation depth is above 1490 nm. When the impression is deeper than 2450 nm, the nanoindentation size effect on the hardness will disappear.

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Crystal Growth: Substructure and Recrystallization

Cited by 12 publications

References 52 publications

Preparation and Investigation of Structural Parameters of Single Crystals of Low‐Alloyed Alloys on the Base of Tungsten and Molybdenum

Preparation and Investigation of Structural Parameters of Single Crystals of Low‐Alloyed Alloys on the Base of Tungsten and Molybdenum

Vacancy cluster growth and thermal recovery in hydrogen-irradiated tungsten

Nanoindentation Size Effect of Tungsten Single Crystal

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