High-Entropy FeCoNiB0.5Si0.5 Alloy Synthesized by Mechanical Alloying and Spark Plasma Sintering

A FeCoNi(B0.5Si0.5) high-entropy alloy with the face-centered cubic (FCC) crystal structure was synthesized by mechanical alloying and spark plasma sintering (SPS). Phase evolution, microstructure, morphology and annealing behaviors were investigated. It was found that a single FCC solid solution appears after 50 h of milling. The grain size was 10 nm after 150 h of milling. Microstructure parameters were calculated by the Rietveld fitting of the X-ray Diffraction patterns. Magnetic characterizations of milled and annealed powders at 650 °C for 1 h were investigated. The heat treatment improves the magnetic properties of the milled powders by enhancing the saturation magnetization value from 94.31 to 127.30 emu/g and decreasing the coercivity from 49.07 to 29.57 Oe. The cohabitation of the FCC phase with the equilibrium crystalline phases observed after annealing is responsible of this magnetic softening. The as-milled powder was also consolidated by spark plasma sintering at 750 and 1000 °C. The obtained specimen consolidated at 750 °C improved the coercivity to 25.06 Oe and exhibited a compressive strength of 1062 Mpa and Vickers hardness of 518 ± 14 HV, with a load of 2 kN. The nanoindentation technique with the Berkovich indentor gave hardness and indentation elastic modulus of 6.3 ± 0.3 Gpa (~640 HV) and 111 ± 4 Gpa for samples consolidated by SPS at 750 °C.

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Effect of Zr Addition on the Microstructure and Mechanical Properties of CoCrFeNiMn High-Entropy Alloy Synthesized by Spark Plasma Sintering

Entropy ◽

10.3390/e20110810 ◽

2018 ◽

Vol 20 (11) ◽

pp. 810 ◽

Cited By ~ 10

Author(s):

Hongling Zhang ◽

Lei Zhang ◽

Xinyu Liu ◽

Qiang Chen ◽

Yi Xu

Keyword(s):

Spark Plasma Sintering ◽

Raw Materials ◽

Alloy System ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

Σ Phase ◽

High Entropy ◽

Plasma Sintering ◽

Spark Plasma ◽

Fcc Phase

As a classic high-entropy alloy system, CoCrFeNiMn is widely investigated. In the present work, we used ZrH2 powders and atomized CoCrFeNiMn powders as raw materials to prepare CoCrFeNiMnZrx (x = 0, 0.2, 0.5, 0.8, 1.0) alloys by mechanical alloying (MA), followed by spark plasma sintering (SPS). During the MA process, a small amount of Zr (x ≤ 0.5) can be completely dissolved into CoCrFeNiMn matrix, when the Zr content is above 0.5, the ZrH2 is excessive. After SPS, CoCrFeNiMn alloy is still as single face-centered cubic (FCC) solid solution, and CoCrFeNiMnZrx (x ≥ 0.2) alloys have two distinct microstructural domains, one is a single FCC phase without Zr, the other is a Zr-rich microstructure composed of FCC phase, B2 phase, Zr2Ni7, and σ phase. The multi-phase microstructures can be attributed to the large lattice strain and negative enthalpy of mixing, caused by the addition of Zr. It is worth noting that two types of nanoprecipitates (body-centered cubic (BCC) phase and Zr2Ni7) are precipitated in the Zr-rich region. These can significantly increase the yield strength of the alloys.

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Phase evolution of refractory high-entropy alloy CrMoNbTiW during mechanical alloying and spark plasma sintering

Journal of Materials Research ◽

10.1557/jmr.2018.483 ◽

2019 ◽

Vol 34 (5) ◽

pp. 756-766 ◽

Cited By ~ 10

Author(s):

Lavanya Raman ◽

K. Guruvidyathri ◽

Geeta Kumari ◽

S.V.S. Narayana Murty ◽

Ravi Sankar Kottada ◽

...

Keyword(s):

Mechanical Alloying ◽

Spark Plasma Sintering ◽

Phase Evolution ◽

High Entropy Alloy ◽

High Entropy ◽

Plasma Sintering ◽

Spark Plasma ◽

Image Position

Abstract

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Phases, Microstructures and Mechanical Properties of CoCrNiCuZn High-Entropy Alloy Prepared by Mechanical Alloying and Spark Plasma Sintering

Entropy ◽

10.3390/e21020122 ◽

2019 ◽

Vol 21 (2) ◽

pp. 122 ◽

Cited By ~ 2

Author(s):

Yuchen Sun ◽

Boren Ke ◽

Yulin Li ◽

Kai Yang ◽

Mingqi Yang ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Alloying ◽

Spark Plasma Sintering ◽

Alloy Powder ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Plasma Sintering ◽

Different Temperatures ◽

Spark Plasma

In the study, an equiatomic CoCrNiCuZn high-entropy alloy (HEA) was prepared by mechanical alloying (MA) and the phases, microstructures, and thermal properties of the alloy powder were explored. The results suggest that a solid solution with body-centered cubic (BCC) phase and a crystalline size of 10 nm formed after 60 h of milling. Subsequently, the alloy powder was consolidated by spark plasma sintering (SPS) at different temperatures (600 °C, 700 °C, 800 °C, and 900 °C). Two kinds of face-centered cubic (FCC) phases co-existed in the as-sintered samples. Besides, Vickers hardness and compressive strength of the consolidated alloy sintered at 900 °C were respectively 615 HV and 2121 MPa, indicating excellent mechanical properties.

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