The high temperature microcrack growth behavior along a planar interface between two elastic dissimilar media is investigated with an aim at estimating service life of advanced ceramic composites under creep-rupture conditions. The crack is assumed to grow along the interface normal to a remote applied tensile stress via a coupled surface and grain-boundary diffusion under steady-state creep conditions. The crack-tip conditions were first derived from the asymmetric tip morphology developed by surface self-diffusion. The governing integro-differential equation containing the unknown tensile stress distribution along the interface ahead of the moving crack tip was derived and it was found that a new length parameter exists as a scaling factor for the interface for which the solution becomes identical to that of the single-phase media when plotted on the nondimensional physical plane. In contrast to the elastic stress solution which shows singularity at the tip and oscillatory character away from the tip, the creep stresses have a peak value away from the tip due to a wedging effect and interfacial sliding eliminates stress oscillation resulting in a decoupling between mode I and mode II stress fields. This stress solution ties the far-field loading parameter to the crack-tip conditions in terms of the unknown crack velocity to give a specific V-K functional relationship. It was shown that a stress exponent of 12 in the conventional power-law crack growth emerges at higher applied stress levels. An analysis on energy balance shows that the energy release during crack growth amounts to the J-integral which derives mostly from work done by “wedging,” not from strain energy loss. A constraint on interfacial diffusivities of the two species was found and its implications on possible microstructural developments were discussed.

1.
Budiansky
B.
,
Hutchinson
J. W.
, and
Evans
A. G.
,
1986
, “
Matrix Fracture in Fiber Reinforced Ceramics
,”
Journal of the Mechanics and Physics of Solids
, Vol.
34
, pp.
167
189
.
2.
Cao
H. C.
,
Dalgleish
B. J.
,
Hsueh
C.-H.
, and
Evans
A. G.
,
1987
, “
High-Temperature Stress Corrosion Cracking in Ceramics
,”
Journal of the American Ceramic Society
, Vol.
70
, pp.
257
264
.
3.
Carroll
D. F.
,
Wiederhorn
S. M.
, and
Roberts
D. E.
,
1989
, “
Technique for Tensile Creep Testing of Ceramics
,”
Journal of the American Ceramic Society
, Vol.
72
, pp.
1610
1614
.
4.
Charles
R. J.
,
1976
, “
Diffusion-Controlled Stress Rupture of Polycrystalline Materials
,”
Metallurgical Transactions
, Vol.
A7
, pp.
1081
1089
.
5.
Chen
I. W.
, and
Argon
A. S.
,
1981
, “
Creep Cavitation in 304 Stainless Steel
,”
Acta Metallurgical
, Vol.
29
, pp.
1321
1333
.
6.
Chuang
T.-J.
, and
Rice
J. R.
,
1973
, “
The Shape of Intergranular Creep Cracks Growing by Surface Diffusion
,”
Acta Metallurgica
, Vol.
21
, pp.
1625
1628
.
7.
Chuang
T.-J.
,
Kagawa
K. I.
,
Rice
J. R.
, and
Sills
B.
,
1979
, “
Overview No. 2: Non-equilibrium Models for Diffusive Cavitation of Grain Interfaces
,”
Acta Metallurgica
Vol.
27
, pp.
265
284
.
8.
Chuang
T.-J.
,
1982
, “
A Diffusive Crack Growth Model for Creep Fracture
,”
Journal of the American Ceramic Society
, Vol.
65
, pp.
93
103
.
9.
Chuang
T.-J.
,
1983
, “
On the Energy Release Rate Associated with Diffusional Crack Growth
,”
International Journal of Fracture
, Vol.
23
, pp.
229
242
.
10.
Chuang, T.-J., and Tighe, N. J., 1989, “Diffusional Crack Growth in Alumina,” Proceed. 3rd International Conference on Fundamental Fracture, Irsee, Germany, pp. 129–132.
11.
Chuang
T.-J.
,
Chu
J. L.
, and
Lee
S.
,
1992
, “
Asymmetric Tip Morphology of Creep Microcracks Growing along Bimaterials Interfaces
,”,
Acta Metallurgica et Materialia
, Vol.
40
, pp.
2683
2691
.
12.
Chuang, T.-J., 1992, “A Generic Model for Creep Rupture Lifetime Estimation on Fibrous Ceramic Composites,” Fracture Mechanics of Ceramics, Vol. 10, R. C. Bradt, D. Hassleman, D. Munz, M. Sakai, and V. Shevchenko, eds. Plenum Press, New York, pp. 441–457.
13.
Dundurs, J., 1968, “Elastic Interaction of Dislocations with Inhomogeneities,” Mathematical Theory of Dislocations, ASME, New York, pp. 70–115.
14.
England
A. H.
,
1965
, “
A Crack Between Dissimilar Media
,”
ASME JOURNAL OF APPLIED MECHANICS
, Vol.
32
; pp.
400
402
.
15.
Evans
A. G.
, and
McMeeking
R. M.
,
1986
, “
On the Toughening of Ceramics by Strong Reinforcements
,”
Acta Metallurgica
, Vol.
34
, pp.
2435
2441
.
16.
Fuentes-Samaniego
R.
, and
Nix
W. D.
,
1981
, “
Steady-state Diffusional Growth of an Axisymmetric Cavity on a Grain Boundary
,”
Philosophical Magazine
, Vol.
44
, pp.
601
612
.
17.
Hirth
J. P.
,
1981
, “
Nucleation of Void Sheets in Creep and Hydrogen Attack
,”
Res, Mechanica Letters
, Vol.
1
, pp.
3
5
.
18.
Hockey
B. J.
,
Wiederhorn
S. M.
,
Liu
W.
,
Baldoni
J. G.
, and
Buljan
S.-T.
,
1991
, “
Tensile Creep of Whisker-Reinforced Silicon Nitride
,”
Journal of Materials Science
, Vol.
26
, pp.
3931
3939
.
19.
Hull
D.
, and
Rimmer
D. E.
,
1959
, “
The Growth of Grain-Boundary Voids under Stress
,”
Philosophical Magazine
, Vol.
42
, pp.
673
687
.
20.
Marshall
D. B.
, and
Cox
B. N.
,
1987
, “
Tensile Fracture of Brittle Matrix Composites: Influence of Fiber Strength
,”
Acta Metallurgica
, Vol.
35
, pp.
2607
2619
.
21.
Nair
S. V.
,
Jakus
K.
, and
Lardner
T. J.
,
1991
, “
The Mechanics of Matrix Cracking in Fiber Reinforced Ceramic Composites Containing a Viscous Interface
,”
Mechanics of Materials
, Vol.
12
, pp.
229
244
.
22.
Nix
W. D.
,
1983
, “
Introduction to the Viewpoint Set on Creep Cavitation
,”
Scripta Metallurgica
, Vol.
17
, pp.
1
43
.
23.
Raj
R.
, and
Ashby
M. F.
,
1975
, “
Intergranular Fracture at Elevated Temperature
,”
Acta Metallurgica
, Vol.
23
, pp.
653
666
.
24.
Rice
J. R.
, and
Chuang
T.-J.
,
1981
, “
Energy Variations in Diffusive Cavity Growth
,”
Journal of the American Ceramic Society
, Vol.
64
, pp.
46
53
.
25.
Rice
J. R.
,
1988
, “
Elastic Fracture Mechanics Concepts for Interfacial Cracks
,”
ASME JOURNAL OF APPLIED MECHANICS
, Vol.
55
, pp.
98
103
.
26.
Speight
M. V.
, and
Harris
J. E.
,
1967
, “
Kinetics of Stress-Induced Growth of Grain-Boundary Voids
,”
Metal Science Journal
, Vol.
1
, pp.
83
85
.
27.
Suo
Z.
,
1989
, “
Singularities Interacting with Interfaces and Cracks
,”
International Journal of Solids and Structures
, Vol.
25
, pp.
1133
1142
.
28.
Svensson
L.-E.
, and
Dunlop
G. L.
,
1981
, “
Growth of Intergranular Creep Cavities
,”
Int. Metals Reviews
, Vol.
2
, pp.
109
131
.
29.
Thouless
M. D.
, and
Liniger
W.
,
1995
, “
Effects of Surface and Boundary Diffusion on Void Growth
,”
Acta Metallurgica et Materialia
, Vol.
43
, pp.
2494
2500
.
30.
Varma
R. K.
, and
Dyson
B. F.
,
1982
, “
Metallographic Detection of Atom-plating due to Cavity Growth
,”
Scripta Metallurgica
, Vol.
16
, pp.
1279
1284
.
31.
Vitek
V.
,
1978
, “
A Theory of Diffusion Controlled Intergranular Crack Growth
,”
Acta Metallurgica
, Vol.
26
, pp.
1345
1356
.
32.
Wiederhorn
S. M.
,
Roberts
D. E.
,
Chuang
T.-J.
, and
Chuck
L.
,
1988
, “
Damage-Enhanced Creep in a Siliconized Silicon Carbide: Phenomenology
,”
Journal of the American Ceramic Society
, Vol.
71
, pp.
602
608
.
33.
Wilkinson
D. S.
, and
Vitek
V.
,
1982
, “
The Propagation of Cracks by Cavitation: A General Theory
,”
Acta Metallurgica
, Vol.
30
, pp.
1723
1733
.
34.
Williams
M. L.
,
1959
, “
The Stresses Around a Fault or Crack in Dissimilar Media
,”
Bull. Seismol. Soc. America
, Vol.
49
, pp.
199
204
.
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