Papers by Author: T. Okane

Abstract: The effect of Fe content on hot tearing of the high-strength Al-Mg-Si alloy was systematically investigated. In this study, a thermodynamic calculation software Thermo-Calc was used to calculate the solidification path under the non-equilibrium condition, and the mechanical properties of this alloy have also been investigated during solidification using an electromagnetic induction heating tensile machine. In order to confirm the calculation results of solidification path, a quenching test also was carried out. By using the Thermo-Calc, the sequence of crystallization, crystallization temperature of formed phases and their crystallized amount were systematically investigated for each alloy in which Fe content was changed. Furthermore, by comparing the fracture surfaces of the tensile testing sample and DC billet, the temperature range of crack initiation of the alloy was examined. Comparing the temperature range of crack initiation with the crystallization phase and its crystallization order, Fe content of high-strength Al-Mg-Si alloy influenced hot tearing significantly owing to the crystallization behavior of α(AlFeMn).

Abstract: An Al foil of 25 µm thickness was used to produce a Ni/Al/Ni interconnection under isothermal conditions at 680°C. After dissolution of the Al filler metal in the Ni substrate, and Ni from the substrate in the Al liquid foil, a solidification process occurred. First of all, the solidification was stopped just at the disappearance of the Al liquid metal, but also at different steps of the progress of solidification. Sub-layers of the two phases Al₃Ni₂ and Al₃Ni were revealed within the frozen joints. A solidification - segregation model was developed to describe the formation of the sub-layers of both mentioned phases. The model is able to predict solute segregation profiles across the sub-layers of the Ni/Al/Ni interconnection, taking into account a superposition of some phenomena like partitioning, back-diffusion into the solid and peritectic reactions. The value of the diffusion coefficient into the solid for the Al₃Ni₂ phase formation in the presence of the liquid is also estimated.