Chanda, Barnasree and Das, Jayanta (2023) Effect of cold working on the rate sensitivity in high entropy lamellar CoCrFeNi(Nb-x/Ta-y) eutectic composites. Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 864. Art No-144557. ISSN 0921-5093

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The strain rate sensitivity (m) and the activation volume (V*) of arc melted ingots (AMIs), suction cast rods (SCRs) of lamellar CoCrFeNiNbx (0.45 <= x <= 0.65) and CoCrFeNiTay (0.2 <= y <= 0.5) eutectic high entropy alloys (EHEAs) comprising of FCC gamma-Ni and Fe2Nb/Co2Ta-type Laves phases have been studied at strain rates of 8 x 10(-5)- 8 x 10(-3)/s. Furthermore, specimens were cold worked up to 55% strain to investigate the effect of prior deformation on the rate sensitivity in bulk specimen using jump test under compression as well as the localized m in the nanoeutectic matrix and micrometer-size pro-eutectic phases using nanoindentation. The m value of the bulk EHEAs with varying lamellae thickness (lambda(w)) of 70-202 nm lies in between 0.0070 and 0.0082, and the V* value lies in between 24.8b(3) and 43.7b(3). Whereas, the localized m value of the eutectic matrix increases from 0.0066 to 0.0075 upon cold working of x = 0.5 SCR. Cold working increases the dislocation density up to 10(16)/ m(2), forms cells, sub-boundaries and distorts the lamellae interface, thus reducing the dislocation mean free path (Lambda) and V*. The local lattice distortion, lamellae thickness, and the dislocation pile-up at the lamellae interface are correlated with the rate sensitivity and related mechanisms in the solute concentrated EHEAs.

Item Type: Article
Subjects: Engineering Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 25 Sep 2023 12:17
Last Modified: 25 Sep 2023 12:17

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