# A Small-Angle Neutron Scattering Methodology for Quantitative Characterization of Channel Width in Gamma Matrix Phase

## TL;DR

This paper introduces a SANS method to measure channel widths in a nickel-based superalloy, showing how heat treatment affects microstructure and element distribution.

## Contribution

A novel SANS methodology is developed for quantitative, bulk characterization of γ matrix channel widths in single-crystal superalloys.

## Key findings

- Virgin state channel widths were nearly isotropic, measuring 17.8 nm and 20.5 nm along different crystallographic directions.
- Heat treatment caused anisotropic coarsening, with widths increasing to 36.8 nm and 28.0 nm, indicating stress-free rafting.
- Elemental redistribution showed Al in γ′ precipitates increased by 2.6 at.%, and Cr in γ channels by 5.9 at.%.

## Abstract

This study establishes a robust small-angle neutron scattering (SANS) methodology for the quantitative characterization of γ matrix channel widths in the nickel-based single-crystal superalloy DD10. By combining SANS with TEM analyses and modeling the one-dimensional SANS data via a polydisperse lamellar model, we accurately determined the channel width distribution across macroscopic sample volumes. In the virgin state, the mean channel widths were nearly isotropic, measuring 17.8 ± 0.1 nm along [002] and 20.5 ± 0.1 nm along [020]. After standard heat treatment (solution and two-step aging), significant anisotropic coarsening was observed, with widths increasing to 36.8 ± 0.2 nm along [002] and 28.0 ± 0.1 nm along [020], indicating stress-free rafting. Elemental mapping revealed substantial redistribution of key alloying elements: Al content in γ′ precipitates increased by 2.6 at.%, while Cr in the γ channels rose by 5.9 at.%. These quantitative results demonstrate that SANS provides reliable, bulk-statistical insights into nanoscale channel geometry, highlighting its critical role in influencing elemental diffusion kinetics and microstructural evolution during thermal exposure.