2001 Volume 48 Issue 8 Pages 685-691
The effect of doping Silicon on the high-temperature deformation of superplastic Yttrium Aluminum Garnet (YS-YAG) was studied under conditions of uniaxial tension. In the preceding paper, the elongation and strain rate of YAG ceramics was described as having decreased by the addition of Si as a sintering aid. This was one of the reasons that the grain size of Si-doped YAG ceramics greatly increased compared with that of non-doped YAG ceramics during deformation. Creep deformation of Y2O3-excess YAG, with an average grain size of 1.6μm, was shown to have an elongation of over 210% (=εn) at 1773 K. Accordingly, we prepared Si-doped Y2O3-excess YAG ceramics (YS-YAG) having the above two chemical composition, and developed YAG materials having two characteristics; remarkable grain growth and elongation. The deformation of YS-YAG reached 200% (=εn) at 1773 K under a constant stress creep tensile test, in spite of the grain size of YS-YAG changed from 1.5 μm to 6μm during deformation.
