Tailoring planar slip to achieve pure metal-like ductility in body-centred-cubic multi-principal element alloys

Liang Wang, Jun Ding, Songshen Chen, Ke Jin, Qiuhong Zhang, Jiaxiang Cui, Benpeng Wang, Bing Chen, Tianyi Li, Yang Ren, Shijian Zheng, Kaisheng Ming, Wenjun Lu, Junhua Hou, Gang Sha, Jun Liang, Lu Wang, Yunfei Xue*, En Ma*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Citations (Scopus)

Abstract

Uniform tensile ductility (UTD) is crucial for the forming/machining capabilities of structural materials. Normally, planar-slip induced narrow deformation bands localize the plastic strains and hence hamper UTD, particularly in body-centred-cubic (bcc) multi-principal element high-entropy alloys (HEAs), which generally exhibit early necking (UTD < 5%). Here we demonstrate a strategy to tailor the planar-slip bands in a Ti-Zr-V-Nb-Al bcc HEA, achieving a 25% UTD together with nearly 50% elongation-to-failure (approaching a ductile elemental metal), while offering gigapascal yield strength. The HEA composition is designed not only to enhance the B2-like local chemical order (LCO), seeding sites to disperse planar slip, but also to generate excess lattice distortion upon deformation-induced LCO destruction, which promotes elastic strains and dislocation debris to cause dynamic hardening. This encourages second-generation planar-slip bands to branch out from first-generation bands, effectively spreading the plastic flow to permeate the sample volume. Moreover, the profuse bands frequently intersect to sustain adequate work-hardening rate (WHR) to large strains. Our strategy showcases the tuning of plastic flow dynamics that turns an otherwise-undesirable deformation mode to our advantage, enabling an unusual synergy of yield strength and UTD for bcc HEAs.

Original languageEnglish
Pages (from-to)950-957
Number of pages8
JournalNature Materials
Volume22
Issue number8
DOIs
Publication statusPublished - Aug 2023

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