Publications by authors named "Yaakov Idell"
Article Synopsis
- - Elemental segregation in additive-manufactured (AM) nickel-based superalloys like Inconel 625 leads to the rapid formation of unwanted δ-phase precipitates during stress-relief heat treatment, happening in minutes compared to the hours needed for traditional wrought alloys.
- - Advanced techniques such as electron microscopy and X-ray scattering show that these δ-phase precipitates grow quickly in their lateral dimensions while their thickness stabilizes early, with nucleation occurring within just 5 minutes.
- - A later homogenization heat treatment can successfully even out the composition of the AM alloy and eliminate the harmful δ phase, suggesting this research approach can be widely applied to other AM materials.
Article Synopsis
- This study employs numerical simulations to analyze microstructure and microsegregation during the rapid solidification of a Ni-based superalloy (Inconel 625) in laser powder bed fusion additive manufacturing.
- Finite element analysis is used to model the laser melt pool, aligning surface temperature results with thermographic data, and subsequently informs mesoscale simulations for solidification phenomena.
- The research contrasts microsegregation predictions from the Scheil-Gulliver model and DICTRA software with experimental microstructures, also evaluating precipitate formation in relation to thermodynamic driving forces at various heat treatment temperatures.
Additively manufactured (AM) metal components often exhibit fine dendritic microstructures and elemental segregation due to the initial rapid solidification and subsequent melting and cooling during the build process, which without homogenization would adversely affect materials performance. In this letter, we report observation of the homogenization kinetics of an AM nickel-based superalloy using synchrotron small angle X-ray scattering. The identified kinetic time scale is in good agreement with thermodynamic diffusion simulation predictions using microstructural dimensions acquired by scanning electron microscopy.
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