Single crystals of Y{sub 3}Al{sub 5}O{sub 12} (YAG) were deformed in air along the [135] direction of 1,635 and 1,785 C using constant strain rate compression. The primary creep region, characterized by ``strain softening,`` persists to at least 4% plastic strain before steady-state behavior is achieved. Creep rates, stress exponents, and activation energies were compared to literature results and suggest the operation of multiple mechanisms over the range of conditions studies. Slip trace analysis confirmed that {l_brace}110{r_brace} was the primary slip system. Slip on both highly stressed (211) and ``anomalous`` (1{bar 1}2) planes was also observed. Dislocation structures were analyzed by transmission electron microscopy and consisted of networks and coarse loops. These results are discussed in terms of asymmetric slip geometry classically observed in body-centered cubic (BCC) metals.
[1]
S. Karato,et al.
High-temperature creep of yttrium-aluminium garnet single crystals
,
1994,
Journal of Materials Science.
[2]
G. Corman.
Creep of yttrium aluminium garnet single crystals
,
1993
.
[3]
E. Courtright,et al.
Ultrahigh Temperature Assessment Study: Ceramic Matrix Composites
,
1992
.
[4]
T. Parthasarathy,et al.
Creep Mechanism of Polycrystalline Yttrium Aluminum Garnet
,
1992
.
[5]
A. Heuer,et al.
Overview No. 6: Interaction between point defects and dislocations in oxides
,
1979
.
[6]
J. Rabier,et al.
Sub-grain boundaries and dissociations of dislocations in yttrium iron garnet deformed at high temperatures
,
1979
.