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Effects of lattice distortion and chemical short-range order on the mechanisms of deformation in medium entropy alloy CoCrNi
- Source :
- Acta Materialia. 199:352-369
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- As the numbers of medium- to high-entropy alloys being studied and impressive structural properties they exhibit increase rapidly, questions regarding the role played by their complex chemical fluctuations rise concomitantly. Here, using a combination of large-scale molecular dynamics (MD), a hybrid MD and Monte-Carlo simulation method, and crystal defect analysis, we investigate the role lattice distortion (LD) and chemical short-range order (CSRO) play in the nucleation and evolution of dislocations and nanotwins with straining in single crystal and nanocrystalline CoCrNi, a medium entropy alloy (MEA). LD and CSRO effects are elucidated by comparisons with responses from a hypothetical pure A-atom alloy, which bears the same bulk properties of the nominal MEA but no LD and no CSRO. The analysis reveals that yield strengths are determined by the strain to nucleate Shockley partial dislocations, and LD lowers this strain, while higher degrees of CSRO increase it. We show that while these partials prefer to nucleate in the CoCr clusters, regardless of their size, they find it increasingly difficult to propagate away from these sites as the level of CSRO increases. After yield, nanotwin nucleation occurs via reactions of mobile Shockley partials and is promoted in MEAs, due to the enhanced glide resistance resulting from LD and CSRO.
- Subjects :
- 010302 applied physics
Materials science
Polymers and Plastics
Alloy
Metals and Alloys
Lattice distortion
Nucleation
02 engineering and technology
engineering.material
021001 nanoscience & nanotechnology
01 natural sciences
Nanocrystalline material
Electronic, Optical and Magnetic Materials
Molecular dynamics
Chemical physics
0103 physical sciences
Ceramics and Composites
Short range order
engineering
Partial dislocations
0210 nano-technology
Single crystal
Subjects
Details
- ISSN :
- 13596454
- Volume :
- 199
- Database :
- OpenAIRE
- Journal :
- Acta Materialia
- Accession number :
- edsair.doi...........0173b2d2b93968687250713c8c46f35c