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

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 810 ◽  
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.

scholarly journals Gradient Distribution of Microstructures and Mechanical Properties in a FeCoCrNiMo High-Entropy Alloy during Spark Plasma Sintering

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 351 ◽  
Author(s):  
Mingyang Zhang ◽  
Yingbo Peng ◽  
Wei Zhang ◽  
Yong Liu ◽  
Li Wang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Intermetallic Particle ◽  
High Entropy Alloy ◽  
Gradient Distribution ◽  
Σ Phase ◽  
High Entropy ◽  
Plasma Sintering ◽  
Graded Material ◽  
Spark Plasma ◽  
Fcc Phase

A novel graded material of a high-entropy alloy (HEA) FeCoCrNiMo was fabricated by spark plasma sintering (SPS) processing. After SPS, the HEA specimens consisted of a single face-centred cubic (FCC) phase in the center, but dual FCC and a tetragonal structure σ phase near the surface. Surprisingly, the sintering pressure was sufficient to influence the proportion of phases, and thus the properties of HEA samples. The hardness of the specimens sintered under the pressures of 30, 35, and 40 MPa increased gradually from 210 HV0.2, which is the single FCC phase in the center, to the maximum value near the surface as a result of the gradual increase in the fraction of the transformed σ phase. The σ phase, being a complex hard and brittle intermetallic particle to manipulate the properties of FCC-type HEA systems, which could be influenced by pressure, indicated a major possibility for designing gradient HEA materials.

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

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 929
Author(s):  
Kaouther Zaara ◽  
Mahmoud Chemingui ◽  
Sophie Le Gallet ◽  
Yves Gaillard ◽  
Lluisa Escoda ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Milled Powder ◽  
Phase Evolution ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Fcc Phase

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.

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

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 122 ◽  
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.

scholarly journals Vacuum brazing of Al2O3 and 3D printed Ti6Al4V lap-joints using high entropy driven AlZnCuFeSi filler

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ashutosh Sharma ◽  
Byungmin Ahn
Keyword(s):  
Strength Properties ◽  
Lap Joints ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
3D Printed ◽  
Face Centered ◽  
Alloy Filler

AbstractIn this work, we studied the brazing characteristics of Al2O3 and 3D printed Ti–6Al–4V alloys using a novel equiatomic AlZnCuFeSi high entropy alloy filler (HEAF). The HEAF was prepared by mechanical alloying of the constituent powder and spark plasma sintering (SPS) approach. The filler microstructure, wettability and melting point were investigated. The mechanical and joint strength properties were also evaluated. The results showed that the developed AlZnCuFeSi HEAF consists of a dual phase (Cu–Zn, face-centered cubic (FCC)) and Al–Fe–Si rich (base centered cubic, BCC) phases. The phase structure of the (Cu–Al + Ti–Fe–Si)/solid solution promises a robust joint between Al2O3 and Ti–6Al–4V. In addition, the joint interfacial reaction was found to be modulated by the brazing temperature and time because of the altered activity of Ti and Zn. The optimum shear strength reached 84 MPa when the joint was brazed at 1050 °C for 60 s. The results can be promising for the integration of completely different materials using the entropy driven fillers developed in this study.

scholarly journals Spark Plasma Sintering of CoCrFeMnNi High-entropy Alloy Powders Produced by Mechanical Alloying

Materia Japan ◽  
2018 ◽  
Vol 57 (7) ◽  
pp. 333-337
Author(s):  
Soo-Hyun Joo ◽  
Takeshi Wada ◽  
Hidemi Kato ◽  
Soon-Jik Hong ◽  
Hyoung Seop Kim
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma
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