“Classical” Superplasticity of SiAlON Ceramics
“Classical” Superplasticity of SiAlON Ceramics
复制标题
SiAlON 陶瓷的“经典”超塑性
DOI：
10.1111/j.1151-2916.1997.tb02990.x
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发表时间：
2005
影响因子：
3.9
通讯作者：
I. Chen
中科院分区：
文献类型：
--
作者：
A. Rosenflanz;I. Chen
研究了名义成分为（YxLiy）0.6/（3x+y）Si8.9Al3.1O2.5N13.5的SiAlON陶瓷的经典超塑性。在变形过程中，这些材料表现出很小的微观结构演变，具有可忽略不计的伸长的α '相晶粒的生长和最小的织构形成。在1500°-1600 ° C的温度范围内，压缩时的应变速率为10 - 2 s-1，在冲压拉伸时，成功使用了1.2 x 10 - 3 s-1的应变速率，可获得出色的成形性。流动应力被发现是显着的晶界相的粘度的影响，并减少锂添加量的增加。断裂应力也是成分依赖性的，并且随着锂含量的增加而降低。由于整体可成形性由断裂和变形之间的竞争决定，因此最大可成形性与中间锂组合物处的断裂应力与成形应力的最大比率一致。最后，所有材料在后成形退火后均表现出更高的室温弯曲强度。因此，瞬时超塑性变形不会损害材料的最终机械性能。
Classical superplasticity of SiAlON ceramics with the nominal composition (Y x Li y ) 0.6/(3x+y) Si 8.9 Al 3.1 O 2.5 N 13.5 is reported in this study. During deformation, these materials exhibit little microstructural evolution, with negligible growth of elongated β'-phase grains and minimal texture formation. Excellent formabilities are obtained in the temperature range of 1500°-1600°C in compression, where a strain rate of 10 -2 s -1 has been achieved, and in punch stretching, where a strain rate of 1.2 x 10 -3 s -1 has been used successfully. Flow stresses are found to be dramatically affected by the viscosity of the grain-boundary phase and decrease as the amount of lithium addition increases. Fracture stress also is compositionally dependent and decreases as the lithium content increases. As the overall formability is determined by the competition between fracture and deformation, maximum formability coincides with a maximum ratio of fracture stress to forming stress at an intermediate lithium composition. Finally, all materials exhibit higher room-temperature bend strength after postforming annealing. Thus, transient superplastic deformation does not impair the ultimate mechanical properties of the materials.