Strain determination of an eutectic single crystal composite Al₂O₃/Y₃Al₅O₁₂ (YAG) by neutron diffraction techniques at reactor and pulsed sources

Abstract

Bragg diffraction angle analysis with a high-resolution strain diffractometer and time-of-flight analysis with backscattering powder diffractometer were complementarily applied to neutron residual strain investigations in an ultra-high temperature resistant composite of eutectic two-phase Al₂O₃/Y₃Al₅O₁₂ (YAG) single-crystal. It was found that the YAG phase was in tension and the Al₂O₃ phase was in compression which resulted in strains ∊ in the range of ∼10⁻⁴ at room temperature, when the measured lattice spacings of the sintered YAG and sintered Al₂O₃ were used as the reference values of strain-free materials. Discussions are given on the methodological points of both analyses with respect to evaluation of a strain value for each phase in the two-phase single crystal materials.

Key Words:

• Ductile composite
• Single crystals Al₂O₃/YAG
• High temperature resistant materials
• Strain measurement
• Neutron diffraction