A global analysis of structural evolution in a row of grains

Sun, Bohua; Suo, Zhigang; Cocks, A.C.F.

doi:10.1016/0022-5096(95)00088-7

Cited by 23 publications

(12 citation statements)

References 29 publications

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“…The desintering phenomenon described above is similar to the morphological instabilities observed in constrained polycrystalline fibres by Miller and Lange [17] and modelled by Sun et al [18]. Polycrystalline fibres, when constrained in a matrix which prevents shrinkage, can break up into isolated spherical grains if the ratio of the grain size to fibre diameter exceeds a critical value.…”

Section: The Sensitivity Of Sintering Time To Initial Contact Sizementioning

confidence: 67%

Constrained sintering of an air-plasma-sprayed thermal barrier coating

Cocks

Fleck

2010

Acta Materialia

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Section: The Sensitivity Of Sintering Time To Initial Contact Sizementioning

confidence: 67%

Constrained sintering of an air-plasma-sprayed thermal barrier coating

Cocks

Fleck

2010

Acta Materialia

Self Cite

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“…We next illustrate these general points in some detail with a row of grains (Sun et al, 1996). Similar problems arise in an electrical interconnect (Srolovitz and Thompson, 1986), powder sintering (Cannon and Carter, 1989), and a fiber constrained on a substrate (Miller and Lange, 1989).…”

Section: B a Row Of Grains-a Model With Two Degrees Of Freedommentioning

confidence: 93%

“…We will use % to indicate the ratio %/%. The free-energy function, G(L,V\ is computed in Miller and Lange (1989) and Sun et al (1996). Figure 18 shows the energy landscape for L 0 /D 0 = 2.5 and % = 150°.…”

Section: Energy Landscapementioning

confidence: 99%

See 1 more Smart Citation

Mechanism-Based Design for High-Temperature, High-Performance Composites. Book 4

Evans¹,

Leckie²,

Hutchinson³

1997

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The paper describes a phase-sensitive photothermal technique for the determination of the thermal conductance of a crack or interface embedded within a plate of finite thickness. The technique involves sinusoidally-modulated heating at one point on the surface using a focused laser beam and measurement of the phase shift of the thermal wave at some other point. An analysis is presented for the relationship between the phase lag, the modulation frequency, the specimen geometry, and the thermal properties of both the interface and the solid. The technique is demonstrated using a model system comprising two stainless steel disks, with the "interfaces" between them being formed either by simply placing the two disks in contact with each another, or by placing thin layers of polyethylene sheets between the disks. The trends are rationalized on the basis of the thermal properties of the constituents.70:FZ6S(8/12/97)January 13. 1998-3:25 PM/mcf INTRODUCTIONThe present article describes a photothermal technique and the associated analysis for the determination of the thermal conductance of a crack or interface embedded within a plate of finite thickness. The technique is based on periodic heating at a point on one surface, using, for example, a focused laser beam, and measurement of the phase lag of the thermal wave at some other point. In the absence of an interface, the technique can be used to determine the thermal diffusivity of the material. The work is motivated by concurrent studies on the thermal conductance of delamination cracks in fiber-reinforced ceramic matrix composites (CMCs) and its effect on failure in the presence of a temperature gradient. An example of such a crack is shown in Fig. 1. Although the technique is being developed mainly to study CMCs, it can be applied readily to other problems involving interfaces or cracks in multilayered or coated systems.Photothermal techniques have been used extensively to study the thermal properties of materials [1][2][3][4][5][6][7][8][9][10][11][12]. A recent summary of these can be found in [12]. The techniques have been used also as nondestructive tools for detecting sub-surface defects [12][13][14][15][16][17][18]. The focus of the present work is on one specific subgroup of these techniques, notably, that based upon periodic heating and phase lag measurement.The main advantage of the present technique is that it provides quantitative information about the thermal conductance of cracks and interfaces, rather than simply identifying regions where such defects are present. This information is crucial for failure prediction in a broad range of technological systems, including delamination of thermally-loaded CMC structures, multilayered power electronic devices and thermal barrier coatings.In the past, thermal conductances have been measured predominantly by dc techniques [19][20][21][22]. These techniques require a heat flux, q, to flow through the 70:FZ6S(8/12/97)January 13, 1998*3:25 PM/mcf interface as well as through the bulk of the two contacting s...

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“…In such cases, the effect of surface oxidaprocesses governed by both energetic and kinetic consideration can be ignored. If we consider lattice diffusion and tions, [53,60] in a complicated 3-D sense. Moreover, the microapplied pressure, the healing rate will be greatly accelerated.…”

Section: B Bifurcation In Evolution Of Microcracks With High-mentioning

confidence: 99%

Morphological healing evolution of intragranular penny-shaped microcracks by surface diffusion: Part I. Simulation

Huang

Sun

et al. 2003

Metall Mater Trans A

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An axisymmetric finite-element method is developed and applied to study spheroidization and breakup of intragranular penny-shaped microcracks by surface diffusion. As the initial aspect ratio of a microcrack increases, it undergoes different sequences of morphological change, evolving into the shapes of a spherical void, a doughnutlike channel pore, a ring with a center void, or multiple rings with or without a center void, while the evolution time continuously increases. During the process of separating into multiple rings, the subsequent separation is a relatively fast process in comparison with the first splitting event. The rate of the morphological evolution depends sensitively on the initial aspect ratio, in particular, the initial thickness, of the microcrack. The simulations also show that the spheroidization rate of a penny-shaped microcrack is much greater than the cylinderization rate of a two-dimensional (2-D) elliptic microcrack, which requires a much larger initially critical aspect ratio for splitting.

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A global analysis of structural evolution in a row of grains

Cited by 23 publications

References 29 publications

Constrained sintering of an air-plasma-sprayed thermal barrier coating

Constrained sintering of an air-plasma-sprayed thermal barrier coating

Mechanism-Based Design for High-Temperature, High-Performance Composites. Book 4

Morphological healing evolution of intragranular penny-shaped microcracks by surface diffusion: Part I. Simulation

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