Calculation and experimental determinations of the residual stress distribution in alumina/Ni/alumina and alumina/Ni/nickel alloy systems

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Residual stress problems encountered in joining ceramics–ceramics or ceramics–metals systems for high-temperature applications >1000 °C have been studied. A solid-state bonding technique under hot-pressing via metallic foils sheet of Ni was used for joining alumina–alumina and alumina–nickel alloy (HAYNES® 214™). The residual stresses expected in the specimen were predicted by finite-element method (FEM) calculations using an elastic–plastic-creep model (EPC). Stress distributions in the specimen were characterized experimentally using X-ray diffraction (XRD) and Vickers Indentation Fracture (VIF) techniques. The tensile and shear stress profiles have been determined along selected lines perpendicular to the bonding interface. The results of the FEM calculation of residual stresses have been compared experimentally with the results of classical XRD and indentation methods. It was found that the tensile stress concentration showed higher values at the edge of the boundary. The residual stresses caused by the thermal expansion mismatch between alumina (Al2O3) and Ni-based super-alloy (HAYNES® 214™) severely deteriorated the joints compared to Al2O3–Al2O3 joint with the same solid-state bonding parameters. The correlations between the FEM calculations and experimental results obtained by XRD and VIF method were discussed.