アルミナ-スピネルセラミックスの高温延性とクラック成長

概要

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High-temperature tensile ductility of Al_2O_3 is much enhanced by spinel (MgO・1.5Al_2O_3) dispersion. However, the enhanced tensile ductility in Al_2O_3-20vol%spinel cannot be explained solely from grain size stability or reduction of flow stress. Detailed microstructural analysis reveals that the crack-like cavity growth rate during high-temperature deformation is more sluggish in Al_2O_3-20vol%spinel than in 0.1wt%MgO-doped single-phase Al_2O_3. The enhanced tensile ductility in Al_2O_3-20vol%spinel must be explained from the reduction of crack-like cavity growth rate during deformation. Since the grain boundaries in Al_2O_3-20vol%spinel mainly consist of Al_2O_3 grain boundaries and Al_2O_3/spinel interphase boundaries, the origin of the sluggish crack-like cavity growth in Al_2O_3-20vol%spinel is due to high resistivity against crack growth in Al_2O_3/spinel boundaries. Detailed TEM analysis clarifies that there is an epitaxial relationship between Al_2O_3 and spinel grains in many Al_2O_3/spinel interphase boundaries. These interphase boundaries are expected to have smaller interfacial energy, which must act to retard the crack-like cavity growth in spinel dispersed Al_2O_3.
社団法人日本材料学会の論文
1997-12-15