Effect of faceting on the thermal grain-boundary grooving of tungsten

Sachenko, P.; Schneibel, J.H.; Zhang, W.

doi:10.1080/01418610208243204

Cited by 20 publications

(9 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Robertson and Chang 29 concluded variations of the surface diffusion coefficient with orientation will lead to non‐uniform grooving and the formation of asymmetric grooves. Multiple studies support this conclusion 30–32 . Thus, the surface roughening observed during the AFM analysis of the annealed YSZ coatings was most likely due to surface diffusivity anisotropy.…”

Section: Discussionmentioning

confidence: 83%

“…showed that poor heat transfer during solidification results in low solidification interface velocity which can lead to microsegregation of yttria at grain or dendrite boundaries. Regarding the validity of Mullins's surface diffusion theories in the presence of surface roughening and faceting, Sachenko et al 31 . showed unfaceted grains and faceted grains that coarsened with further annealing remained in qualitative agreement with Mullins's theories.…”

Section: Discussionmentioning

confidence: 96%

“…Thus, the surface roughening observed during the AFM analysis of the annealed YSZ coatings was most likely due to surface diffusivity anisotropy. The diffusion variations may be induced by crystallographic faceting from surface energy anisotropy 31,33 of the plasma‐sprayed coating or a heterogeneous composition across the surface of the coating 34 . The distribution of yttrium atoms within the lamellar microstructure depends on the interface morphology adopted during solidification 35 .…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Grain‐Boundary Grooving of Plasma‐Sprayed Yttria‐Stabilized Zirconia Thermal Barrier Coatings

Erk

Deschaseaux

Trice

2006

Journal of the American Ceramic Society

View full text Add to dashboard Cite

The focus of this study was to determine the mechanisms responsible for the microstructural changes of plasma‐sprayed 7 wt% Y2O3–ZrO2 thermal barrier coatings with annealing from 800° to 1400°C. Mullins's thermal grooving theories have been applied to plasma‐sprayed TBCs to determine the dominant mass transport mechanism at various temperatures. Grain‐boundary groove widths were measured as a function of annealing time and temperature using atomic force microscopy (AFM). The same collection of grains was analyzed after progressive heat treatments. Surface diffusion was found to be the dominant diffusion mechanism at 1000°C, corresponding to the disappearance of intralamellar cracks at that temperature. At 1100°C, both surface and volume diffusion were active. Volume diffusion, found to be the dominant diffusion mechanism at 1200°C and above, was responsible for the sintering of interlamellar pores observed from AFM analysis of a single, progressively heat‐treated interlamellar boundary. Surface roughening was observed to coarsen with increased annealing time and disappear with increased annealing temperature.

show abstract

Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Grain‐Boundary Grooving of Plasma‐Sprayed Yttria‐Stabilized Zirconia Thermal Barrier Coatings

Erk

Deschaseaux

Trice

2006

Journal of the American Ceramic Society

View full text Add to dashboard Cite

show abstract

“…Surface energy effects in thin films are known to produce thermal grooving at the intersection of grain boundaries with the film surface, 59 which has been connected to local pinning of the boundaries 31,60 and the growth of grains through a discontinuous process. 36 Given that the nanocrystalline tungsten films were appreciably thin (i.e., 25-30 nm), surface energy effects likely contributed to the onset of abnormal grain growth and the rate at which metastable b transformed to the equilibrium a-phase.…”

Section: Fig 6 Inverse Pole Figures For the Combined Reliability-ormentioning

confidence: 99%

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

et al. 2017

View full text Add to dashboard Cite

Microstructure and phase evolution in magnetron sputtered nanocrystalline tungsten and tungsten alloy thin films are explored through in situ TEM annealing experiments at temperatures up to 1000°C. Grain growth in unalloyed nanocrystalline tungsten transpires through a discontinuous process at temperatures up to 550°C, which is coupled to an allotropic phase transformation of metastable b-tungsten with the A-15 cubic structure to stable body centered cubic (BCC) a-tungsten. Complete transformation to the BCC a-phase is accompanied by the convergence to a unimodal nanocrystalline structure at 650°C, signaling a transition to continuous grain growth. Alloy films synthesized with compositions of W-20 at.% Ti and W-15 at.% Cr exhibit only the BCC a-phase in the as-deposited state, which indicate the addition of solute stabilizes the films against the formation of metastable b-tungsten. Thermal stability of the alloy films is significantly improved over their unalloyed counterpart up to 1000°C, and grain coarsening occurs solely through a continuous growth process. The contrasting thermal stability between W-Ti and W-Cr is attributed to different grain boundary segregation states, thus demonstrating the critical role of grain boundary chemistry in the design of solute-stabilized nanocrystalline alloys. transition with a focus on harsh environment sensors produced by additive manufacturing processes. Professor Trelewicz's research is on the science of interface engineered alloys with particular emphasis on high-strength and radiation-tolerant nanomaterials for extreme environment applications. His group couples in situ and analytical characterization tools with large-scale atomistic simulations to explore the thermal stability, mechanical behavior, and radiation tolerance of solute-stabilized nanocrystalline alloys, crystalline-amorphous nanolaminates, metallic glass matrix composites, and other unique hierarchical metallic structures. Professor Trelewicz is a recipient of the 2017 DOE Early Career

show abstract

“…Three typical groove morphologies were observed: (i) Mullins-like, albeit asymmetrical grooves with the sharp root; (ii) grooves with the blunted root, and (iii) grooves with the blunted root with the secondary sub-groove with the sharp root in the region of a primary groove. Sachenko et al [47][48][49] and Zhang et al [25,27] studied GB grooving on the surfaces of polycrystalline tungsten sheets. They found that unfaceted grooves were in qualitative agreement with the predictions of Mullins' theory of grooving by surface diffusion mass transport.…”

Section: Experimentally Observed Thermal Groovesmentioning

confidence: 99%

Thermal Grooving by Surface Diffusion: a Review of Classical Thermo-Kinetics Approach

Akyıldız

Oǧurtani

2017

Hittite J. Sci. Eng.

View full text Add to dashboard Cite

P olycrystalline materials are composed of tiny perfect crystalline regions (grains) in between internal interfaces called grain boundaries. Grain boundaries and the external interfaces (i.e. free surfaces which separate the material from the environment) determine the morphology of the material at a major extent. A material may change its morphology through interface motion if a driving force exists. An important special case, which is the focus of this review, is the grain boundary grooving. Wherever a grain boundary intersects a free surface and whenever the topographic variation associated with the atomic motion is favored by total free energy dissipation, the surface grooves. Grooving can occur via several mass transport mechanisms, such as surface diffusion, bulk diffusion, and evaporation and condensation. Surface diffusion dominates for temperatures far below the melting temperature, and for grooves less than 10 micron in size [1]. If the surface evolution is driven solely by the total excess free energies associated with the interfaces the resulting force for motion is conventionally called a capillary force,

show abstract

Effect of faceting on the thermal grain-boundary grooving of tungsten

Cited by 20 publications

References 13 publications

Grain‐Boundary Grooving of Plasma‐Sprayed Yttria‐Stabilized Zirconia Thermal Barrier Coatings

Grain‐Boundary Grooving of Plasma‐Sprayed Yttria‐Stabilized Zirconia Thermal Barrier Coatings

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

Thermal Grooving by Surface Diffusion: a Review of Classical Thermo-Kinetics Approach

Contact Info

Product

Resources

About