Elucidating hierarchical microstructures in high entropy superalloys: An integrated multiscale study

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization Pub Date : 2025-02-01 DOI:10.1016/j.matchar.2024.114642

Erika Zaiser , Andrea Fantin , Anna M. Manzoni , René Hesse , Daniel M. Többens , Wei-Che Hsu , Hideyuki Murakami , An-Chou Yeh , Michael J. Pavel , Mark L. Weaver , Huihui Zhu , Yuan Wu , Florian Vogel

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引用次数: 0

Abstract

In this study, we examine a high entropy superalloy (HESA-Y1: Ni_49.37Co₂₀Cr₇Fe₄Al_11.6Ti₆Re₁Mo_0.5W_0.5Hf_0.03 at%), focusing on hierarchical microstructure formation and its effects on mechanical properties. Thermodynamic modeling using Thermo-Calc predicts equilibrium phase fractions, compositions, and transition temperatures, which are validated by experimental data from differential scanning calorimetry (DSC). Transmission electron microscopy (TEM) reveals that secondary aging induces nanometer-sized γ particles within γ' precipitates, forming a hierarchical γ/γ' microstructure. Atom probe tomography (APT) confirms supersaturation of γ' precipitates with γ-forming elements (Co, Cr, Fe), driving γ particle formation, and measures interfacial widths between γ' and γ phases. Partitioning coefficients derived from APT align with Thermo-Calc predictions for most elements. Vickers microhardness testing shows an increase of about 50 HV in the hierarchical microstructure compared to the conventional one. In situ synchrotron X-ray diffraction (XRD) from 25 to 750 °C determines a small, negative lattice misfit δ between γ and γ' phases, suggesting enhanced microstructural stability, consistent with Thermo-Calc calculations. Our methodological approach enables measurement of the unconstrained lattice parameter of phase-extracted γ' in a single-crystal XRD setup. Due to their small size and low volume fraction, γ particles do not produce distinct reflections in the X-ray diffractogram. Elucidating hierarchical microstructures across multiple scales, we establish that the presence of Re and Hf and controlled aging processes lead to enhanced mechanical properties, offering valuable insights for the design of advanced high entropy superalloys.

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来源期刊

Materials Characterization 工程技术-材料科学：表征与测试

CiteScore

7.60

自引率

8.50%

发文量

746

审稿时长

36 days

期刊介绍： Materials Characterization features original articles and state-of-the-art reviews on theoretical and practical aspects of the structure and behaviour of materials. The Journal focuses on all characterization techniques, including all forms of microscopy (light, electron, acoustic, etc.,) and analysis (especially microanalysis and surface analytical techniques). Developments in both this wide range of techniques and their application to the quantification of the microstructure of materials are essential facets of the Journal. The Journal provides the Materials Scientist/Engineer with up-to-date information on many types of materials with an underlying theme of explaining the behavior of materials using novel approaches. Materials covered by the journal include: Metals & Alloys Ceramics Nanomaterials Biomedical materials Optical materials Composites Natural Materials.