Dislocation mechanisms and 3D twin architectures generate exceptional strength-ductility-toughness combination in CrCoNi medium-entropy alloy

By Zijiao Zhang, H. Sheng, Zhangjie Wang, B. Gludovatz, Ze Zhang, Easo P. George, Qian Yu, S. Mao, R. Ritchie. Nature Communications, 2017

652 citations recorded by the source corpus.

Combinations of high strength and ductility are hard to attain in metals. Exceptions include materials exhibiting twinning-induced plasticity. To understand how the strength-ductility trade-off can be defeated, we apply in situ, and aberration-corrected scanning, transmission electron microscopy to examine deformation mechanisms in the medium-entropy alloy CrCoNi that exhibits one of the highest combinations of strength, ductility and toughness on record. Ab initio modelling suggests that it has negative stacking-fault energy at 0K and high propensity for twinning. With deformation we find that a three-dimensional (3D) hierarchical twin network forms from the activation of three twinning systems. This serves a dual function: conventional twin-boundary (TB) strengthening from blockage of dislocations impinging on TBs, coupled with the 3D twin network which offers pathways for dislocation glide along, and cross-slip between, intersecting TB-matrix interfaces. The stable twin architecture is not disrupted by interfacial dislocation glide, serving as a continuous source of strength, ductility and toughness. Materials that show twinning-induced plasticity can offer unusual combinations of strength and ductility. Here, authors study deformation twinning and dislocation behaviour in a medium-entropy alloy CrCoNi and find a three-dimensional (3D) hierarchical twin network that forms from the activation of three twinning systems.

Subfields: Aerospace Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/eb0bdfa16c3c26b264eac7a99fb5b7595b3aed6d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Aerospace Engineering

1. Shiteng Zhao
2. M. Meyers
3. Zezhou Li
4. Xianglin Liu
5. R. Ritchie
6. Mark Asta
7. Zongrui Pei
8. Jiaxin Zhang

In Mechanical Engineering

1. Shiteng Zhao
2. M. Meyers
3. Zezhou Li
4. Jian Lu
5. Ligang Sun
6. Xiaoqiao He
7. Xianglin Liu
8. R. Ritchie

Citations in the corpus

• Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys (2018, background): “, −24 mJ·m (11), −62 mJ·m (17), or −41 mJ·m (18), which are apparently at odds with the measured finite dislocation dissociation widths.”
• Machine Learning for High-entropy Alloys: Progress, Challenges and Opportunities (2022, background): “The first one is their exceptional mechanical properties, such as the exceptional high-temperature properties [14], enhanced strength, ductility and toughness at cryogenic temperatures [15, 16], and most importantly the excellent combination of strength and ductility [2, 17, 18, 19, 20, 21, 22, 23, ”
• Nanotwinned and hierarchical nanotwinned metals: a review of experimental, computational and theoretical efforts (2018, background): “Several approaches have been proposed, such as bimodal or multimodal grain-size distribution, second-phase particle hardening, dual-phase nanostructuring,(22) fabricating high dislocation density in deformation-induced martensitic transformation system,(23) introducing NT structures into nanosized g”