arXiv subjects

David N. Seidman

Publications and source records attributed to David N. Seidman.

20 records · Page 2Linked to original sources

arXiv2007

Best-Fit Ellipsoids of Atom-Probe Tomographic Data to Study Coalescence of Gamma Prime (L1_2) Precipitates in Ni-Al-Cr

An algorithm is presented to fit precipitates in atom probe tomographic data sets as equivalent ellipsoids. Unlike previous techniques, which measure only the radius of gyration, these ellipsoids retain the moments of inertia and principle axes of the original precipitate, preserving crystallographic orientational information. The algorithm is applied to study interconnected gamma prime precipitates (L1_2) in the Gamma-matrix (FCC) of a Ni-Al-Cr alloy. The precipitates are found to coagulate along <110>-type directions.

cond-mat.mtrl-sci↗

arXiv2006

Direct observations of nucleation in a nondilute multicomponent alloy

The chemical pathways leading to gamma-prime(L1_2)-nucleation from nondilute Ni-5.2 Al-14.2 Cr at.%, gamma(f.c.c.), at 873 K are followed with radial distribution functions and isoconcentration surface analyses of direct-space atom-probe tomographic images. Although Cr atoms initially are randomly distributed, a distribution of congruent Ni3Al short-range order domains (SRO), =0.6 nm, results from Al diffusion during quenching. Domain site occupancy develops as their number density increases leading to Al-rich phase separation by gamma-prime-nucleation, =0.75 nm, after SRO occurs.

cond-mat.mtrl-sci↗