Effect of Powder Morphology and Chemical Distribution on Properties of Multicomponent Alloys Produced Via Powder Metallu
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Effect of Powder Morphology and Chemical Distribution on Properties of Multicomponent Alloys Produced Via Powder Metallurgy Seungjin Nam1 · Se Eun Shin2 · Jae‑Hun Kim1 · Hyunjoo Choi1 Received: 13 February 2020 / Accepted: 12 May 2020 © The Korean Institute of Metals and Materials 2020
Abstract In this study, effects of morphology and chemical distribution of powder on mechanical properties was investigated in Al0.5CoCrCuFeNi high-entropy alloys produced via powder metallurgy. At the early stages of ball-milling, Cr-deficient large powder is flattened, while Cr-rich powder is fractured to small particles because of the flattening of ductile particles and fragmentation of hard particles at initial milling stage. However, with an increase in the milling duration, the Cr atoms were more uniformly distributed throughout the powders and the powders exhibited spherical shape with smooth surface. Moreover, as the ball-milling duration increased from 36 to 96 h, the Vickers hardness and compressive yield strength also v0.5 and 1739 MPa, respectively. This was attributed to the spherical powders increased from 433 H v0.5 and 1166 MPa to 525 H reducing as well as forming fine and uniform microstructures in sintered alloys. Also, the elemental uniformity suppressed the formation of dendritic-unfavorable carbides. Keywords High-entropy alloy · Powder metallurgy · Powder shape · Chemical distribution · Mechanical properties
1 Introduction Since the report of the concept of high-entropy alloys (HEAs) in the year 2004 [1], many researchers have investigated phase evolution in HEAs and their mechanical behavior [2, 3]. HEAs are multi-component alloy systems comprising of at least five principal alloying elements with either equiatomic or near-equiatomic ratio. CoCrCuFeNi-based HEAs have been widely used due to their high strength at room temperature and good forming ability [4]. Although an equiatomic CoCrCuFeNi-based HEA exhibits a single solidsolution phase with a face-centered cubic (FCC) structure, the phase is transformed into a body-centered cubic (BCC) phase on the addition of Al to the alloy [5]. Even though the formation of a BCC phase enhances the strength of the structure by lattice distortion as a result of the atomic size misfit * Jae‑Hun Kim [email protected] * Hyunjoo Choi [email protected] 1
Department of Advanced Materials Engineering, Kookmin University, Seoul 02707, Republic of Korea
Department of Advanced Materials Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
2
and hard phase [6], deformation could be limited considering the strength-ductility trade-off [7]. Hence, A l0.5CoCrCuFeNi HEAs are considered to be promising structural materials due to their valence mechanical properties [8]. In recent times, powder metallurgy (PM), which generally involves mechanical alloying followed by consolidation, has been used to produce HEAs with homogenous and fine microstructures [9–11]. Mechanical alloying allows atomic-level mixing among alloying elements even a
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