A High-Resolution Method to Map Out the γ/γ' Lattice Misfit in Ni-Based Superalloys

44 Pages Posted: 30 Oct 2019

See all articles by Jiawei Kou

Jiawei Kou

Xi'an Jiaotong University (XJTU), School of Material Science and Engineering, Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano)

Yao Li

Chang’an University - School of Materials Science and Engineering

Ching-Shun Ku

National Synchrotron Radiation Research Center

Evan Ma

Johns Hopkins University - Department of Materials Science and Engineering

Kai Chen, Ph.D.

Xi'an Jiaotong University (XJTU) - Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano)

Date Written: October 23, 2019

Abstract

Lattice misfit is an essential parameter/property that affects the mechanical behavior of two-phase superalloys. Here we report a new method to use sub-micrometer-focused synchrotron X-ray beam to directly measure the γ/γ′ misfit in Ni-based superalloys. By combining polychromatic X-ray Laue diffraction and monochromatic energy scan, the lattice constants of both phases and the lattice misfit are mapped out at high spatial resolution, which is only limited by the X-ray beam size and scanning step size. We also developed data analysis algorithms to elevate the reliability of peak fitting and the precision and accuracy of lattice constants/misfit measurements. The success of our method is illustrated by uncovering the pronounced variations and non-monotonic profiles of the misfit and phase fractions throughout the heat affected zone in a laser 3D-printed Ni-based superalloy. The nano-hardness distribution in the transition region from the base metal to the cladding layers is empirically correlated with the phase fractions that are reflected by the diffraction peak intensities.

Keywords: lattice misfit, Ni-based superalloys, synchrotron X-ray nanodiffraction, additive manufacturing, phase fraction

Suggested Citation

Kou, Jiawei and Li, Yao and Ku, Ching-Shun and Ma, Evan and Ph.D., Kai Chen,, A High-Resolution Method to Map Out the γ/γ' Lattice Misfit in Ni-Based Superalloys (October 23, 2019). Available at SSRN: https://ssrn.com/abstract=3474534 or http://dx.doi.org/10.2139/ssrn.3474534

Jiawei Kou (Contact Author)

Xi'an Jiaotong University (XJTU), School of Material Science and Engineering, Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano)

Xi’an
China

Yao Li

Chang’an University - School of Materials Science and Engineering

Xi’an
China

Ching-Shun Ku

National Synchrotron Radiation Research Center

Hsinchu, 30076
Taiwan

Evan Ma

Johns Hopkins University - Department of Materials Science and Engineering ( email )

Baltimore, MD 20036-1984
United States

Kai Chen, Ph.D.

Xi'an Jiaotong University (XJTU) - Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano)

China

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