Influence of heat treatment on microstructure, mechanical behavior, and soft magnetic properties in an fcc-based Fe 29 C
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Todd C. Monsonb) Nanoscale Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
Baolong Zheng Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California 92697, USA
Weiping Chen Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, Guangzhou, Guangdong 510640, China
Enrique J. Laverniaa) Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California 92697, USA (Received 16 February 2018; accepted 7 May 2018)
The influence of heat treatment (homogenization) on the microstructure, mechanical behavior, and soft magnetic properties of a face-centered cubic (fcc)-based high-entropy alloy (HEA), Fe29Co28Ni29Cu7Ti7, fabricated by casting, was investigated in detail. The as-cast Fe29Co28Ni29Cu7Ti7 HEA was composed of a primary fcc phase containing coherent dispersed L12 nanoprecipitates and trace amounts of a needle-like phase. The tensile yield strength (r0.2), ultimate strength, and total elongation of the as-cast alloy are 917 MPa, 1060 MPa, and 1.8%, respectively. Following homogenization, the alloy having a single fcc phase shows a decrease of ; 55% in yield strength and a decrease of ; 36% in ultimate strength; however, the total elongation is increased from 1.8 to 52%. Saturation magnetization (Msat) is decreased from 111.54 to 110.34 Am2/kg, by contrast, coercivity (Hc) is increased from 266.65 to 966.89 A/m. The dissolution of precipitates and grain growth are mainly responsible for the changes in magnetic properties and mechanical behavior.
I. INTRODUCTION
During the past decade, high-entropy alloys (HEAs) have become of interest because they provide a potential “paradigm shift” in the way we design alloys. Unlike conventional alloys, which only have one or two principal elements, HEAs are composed of five or more principal elements with 5–35 at.% concentrations for each element.1,2 This unique compositional architecture can induce a high entropy of mixing, particularly at high temperatures, that can promote the formation of the HEAs defining feature, that is a multi-element random a)
Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/editor-manuscripts/. DOI: 10.1557/jmr.2018.161
solid solution, in which each element has the same probability to occupy any given site in a simple crystal structure.2 Consequently, instead of intermetallic phases, solid-solution phases with simple crystal structures, that is, face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal close-packed (hcp) structures, are generally formed in the HEAs.3–5 Several proposed phenomena, including severe lattice distortion, sluggish diffusion kinetics, and a high-entropy effect have been argued to play a role in the observed physical and mechanica
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