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Unexpected ¿-Phase Formation in Additive Manufactured Ni-based Super Alloy



Yaakov S. Idell, Lyle E. Levine, Andrew J. Allen, Fan Zhang, Carelyn E. Campbell, Greg Olson, Jiadong Gong, David Snyder


An as-built and solutionized Ni-based super alloy built by additive manufacturing through a direct metal laser sintering technique is characterized to understand the microstructural differences as compared to the as-wrought alloy. The rapid solidification process produces significant microsegregation of niobium, which allows formation of the deleterious δ-phase due to the microstructural chemical inhomogeneity. The as-built microstructure was characterized through Vickers hardness, optical microscopy, scanning and transmission electron microscopy, electron back scattering diffraction, X-ray diffraction, and synchrotron X-ray microLaue diffraction. Additionally, the growth and formation of the δ-phase was monitored through synchrotron-based in-situ small angle and wide angle X-ray scattering measurements. These results are compared with multicomponent diffusion simulations that predict the phase fraction and composition. The high residual stresses and unexpected formation of the δ-phase will require further annealing treatments to be designed so as to remove these deficiencies and obtain an optimized microstructure.
JOM Journal of the Minerals Metals and Materials Society


718Plus, USAXS, Δ phase, EBSD, EDS


Idell, Y. , Levine, L. , Allen, A. , Zhang, F. , Campbell, C. , Olson, G. , Gong, J. and Snyder, D. (2016), Unexpected ¿-Phase Formation in Additive Manufactured Ni-based Super Alloy, JOM Journal of the Minerals Metals and Materials Society, [online], (Accessed July 13, 2024)


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Created January 8, 2016, Updated November 10, 2018