The Effect of silicon Addition on high-Temperature Tensile Deformation of Superplastic Yttrium Aluminum Garnet (YAG) Ceramics

摘要

The effect of doping Silicon on the high-temperature deformation of superplastic Yttrium 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 o f 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. Greep deformation of Y_2O_3-excess YAG, with an average grain size of 1.6#mu#m, was shown to have an elongation of Si-over 21percent (=ε_n) at 1773K. Accordingly, we prepared Si-doped Y_2O_3-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 percent (=ε_n) at 1771K under a constant stress creep tensile test, in spite of the grain size of YS-YAG changed from 1.5#mu#m to 6#mu#m during deformation.