Atomic-scale study on core-shell Cu precipitation in steels: atom probe tomography and ab initio calculations

arXiv (Cornell University)

Abstract

The present work investigates the atomic interactions among Cu, Al, and Ni elements in bcc-iron matrix, focusing on the formation mechanism of nano-sized core-shell Cu precipitates. Using a combination of atom probe tomography (APT), density functional theory (DFT) cal-culations, and molecular dynamics (MD) simulations, the study provides insights into the atomic-scale migration tendencies of these elements in the supersaturated solid solution sur-rounding Cu precipitate in the martensite phase of a medium-Mn steel. The results show that Ni and Al atoms were not expelled by Cu atoms but were instead attracted to the bcc iron matrix, forming a stable co-segregation in the outer shell. This phase effectively surrounded the nano-sized Cu precipitate and prevented its rapid growth, contributing to improved me-chanical properties. The findings offer a theoretical method for developing Cu-contaminated circular steels by utilizing DFT calculations to unravel bonding preferences and assess the po-tential for forming a stable precipitation phase around nano-sized Cu precipitates.

Authors 6

1. Xiao Huan Shen Aachen Steel Institute

   University of Kassel · RWTH Aachen University

   Affiliation as printed

   Institute of Materials Engineering , University of Kassel , Mönchebergstr. 3 , 34125 Kassel , Germany

   Steel Institute , RWTH Aachen University , Intzestr. 1 , 52072 Aachen , Germany

2. Yixu Wang Aachen Institute of Inorganic Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Inorganic Chemistry , RWTH Aachen University , Landoltweg 1 , 52056 Aachen , Germany

3. Zigan Xu Aachen Steel Institute

   RWTH Aachen University

   Affiliation as printed

   Steel Institute , RWTH Aachen University , Intzestr. 1 , 52072 Aachen , Germany

4. Enzo Liotti

   University of Oxford

   Affiliation as printed

   Department of Materials , University of Oxford , Parks Road , OX1 3PH Oxford , UK

5. Richard Dronskowski Aachen Institute of Inorganic Chemistry

   RWTH Aachen University

   Affiliation as printed

   Institute of Inorganic Chemistry , RWTH Aachen University , Landoltweg 1 , 52056 Aachen , Germany

6. Wenwen Song Aachen Steel Institute

   University of Kassel · RWTH Aachen University

   Affiliation as printed

   Institute of Materials Engineering , University of Kassel , Mönchebergstr. 3 , 34125 Kassel , Germany

   Steel Institute , RWTH Aachen University , Intzestr. 1 , 52072 Aachen , Germany