Title: Friction stir gradient alloying: A high-throughput method to explore the influence of V in enabling HCP to BCC transformation in a γ-FCC dominated high entropy alloy

Abstract

The compositional possibilities in high entropy alloys (HEAs) is very vast and effective strategies are needed to establish potential alloy chemistries. In this study, friction stir gradient alloying (FSGA), a recently-introduced high-throughput (HT) technique incorporating compositional and microstructural gradients, was used to explore the possibility of introducing a bcc transformation domain in γ-fcc dominated TRIP HEA Fe_38.5Mn₂₀Cr₁₅Co₂₀Si₅Cu_1.5 (at.%) by vanadium addition. FSGA has accelerated the process of attaining the composition-microstructure library and the results suggest that vanadium addition of ~1 at.% results in nucleation of α-bcc. Additionally, this is the first observation of ε-hcp to α-bcc transformation in a TRIP HEA and supports the Olson-Cohen model of martensitic transformation (γ-fcc → ε-hcp → α-bcc). ε-hcp is nucleated with a pyramidal orientation by the formation of planar faults on the {111} close-packed planes of γ-fcc, and α-bcc is nucleated in the vicinity of ε-hcp along the {111} γ-fcc trace. There are indications for the formation of basal orientated ε-hcp from intersecting ε-hcp planes orientated for the pyramidal slip. Thus, the study shows the nucleation and growth of the α-bcc phase attributed to the dual effects of chemistry and strain and potential co-existence of all the three phases.

Authors:

Agrawal, Priyanka ^[1]; Shukla, Shivakant  ^[2];

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Gupta, Sanya ^[3]; Agrawal, Priyanshi ^[1]; Mishra, Rajiv S. ^[1]

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+ Show Author Affiliations

1. Univ. of North Texas, Denton, TX (United States). Center for Friction Stir Processing; Univ. of North Texas, Denton, TX (United States). Advanced Materials and Manufacturing Processes Inst.
2. Univ. of North Texas, Denton, TX (United States). Center for Friction Stir Processing; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Univ. of North Texas, Denton, TX (United States). Center for Friction Stir Processing

Publication Date:

Tue Oct 13 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1779117

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Applied Materials Today

Additional Journal Information:

Journal Volume: 21; Journal Issue: 21; Journal ID: ISSN 2352-9407

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Friction stir gradient alloying; transforming high entropy alloys; vanadium alloying; HCP-BCC transformation