Search

Pulsed electric current sintering (PECS) technique, which can highly control sintering conditions with uniaxial pressing under vacuum, is effective in fabricating various functional materials. Particularly, high densification rates attained by this sintering technique enable suppressed grain growth during sintering process results in finegrained microstructures. For laser optics, we show that PECS is also effective for fabricating non-cubic laser materials with fine microstructure, and sapphire/Nd:YAG ceramic composite materials. In this paper, we describe the microstructure, optical characteristics, and lasing properties for the fabricated materials and discuss the future possibility of PECS for applying to laser optics. [ABSTRACT FROM AUTHOR]

For attaining high-strain-rate superplasticity (HSRS) in ceramic materials, prerequisites are described on the basis of existing knowledge about high-temperature plastic deformation and intergranular cavitation mechanisms. The knowledge suggests that a combination of grain-size refinement to 100-200 nm or smaller and enhanced diffusion caused by doping may highly enhance stress-relaxation around triple junctions and may lead to HSRS at temperatures lower than 1250-1300°C in structural ceramics. From this point of view, recent studies are reviewed and discussed on ceramic superplasticity at strain rates higher than 1 × 10−2 s−1. Attention is also placed on the fabrication of materials with nanosized grains and the resultant superplastic properties. [ABSTRACT FROM AUTHOR]