期刊
ACTA MATERIALIA
卷 118, 期 -, 页码 350-361出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2016.07.055
关键词
Precipitation hardening; Stacking fault ribbon; Dislocation creep; ab initio calculation; Phase field simulation
资金
- NSF DMREF program [DMR-1534826]
- Materials Affordability Initiative Program on Integrated Microstructure and Process Modeling of Alloy 718 Aerospace Components
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1534826] Funding Source: National Science Foundation
High-temperature alloys in general and superalloys in particular are strengthened by ordered intermetallic phases that are relatively stable at elevated temperatures. Because of their low symmetry, however, these ordered intermetallic phases have rather complicated deformation mechanisms that are difficult to uncover by experiment alone. In this study we use a combination of qb initio calculation and phase field simulation at the elementary defect level to illustrate how dislocations interact with precipitates of an ordered intermetallic phase, r '' (D0(22), tetragonal), the primary strengthening phase in Ni-Nb-Fe-Cr-Ti-Al-Mo alloy (Inconel 718 or IN718 superalloy). A rich variety of new and sophisticated deformation mechanisms are discovered, including a novel mechanism of dislocation generation (accompanied by a spontaneous stacking fault (SF) transition), formation of superlattice intrinsic SF ribbons (SISF-ribbons) and 1/3<112>-type compact super-dislocations, along with ISF shearing and Orowan looping. The predicted deformation microstructures seem to agree with recent electron microscopy observations in IN718. The detailed deformation mechanisms uncovered can be incorporated in constitutive microstructure-property relationships for advanced crystal plasticity modeling and the approach developed can be used to study plastic deformation of other intermetallic phases in different alloy systems. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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