scholarly journals Improved Tribocorrosion Resistance by Addition of Sn to CrFeCoNi High Entropy Alloy

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Piyanut Muangtong ◽  
Righdan Mohsen Namus ◽  
Russell Goodall
Keyword(s):  
Intermetallic Phase ◽  
Quaternary Alloy ◽  
High Entropy Alloy ◽  
Ductile Phase ◽  
High Entropy ◽  
Chloride Corrosion ◽  
Quinary System ◽  
Fcc Phase ◽  
Fcc Structure ◽  
Resist Crack Propagation

Among the high entropy or complex concentrated alloys (HEAs/CCAs), one type of system is commonly based on CoCrFeNi, which as an equiatomic quaternary alloy that forms a single phase FCC structure. In this work, the effect of Sn in an equiatomic quinary system with CoCrFeNi is shown to lead to a great improvement in hardness and resistance to tribocorrosion. The addition causes a phase transition from a single FCC phase in CoCrFeNi to dual phase in CoCrFeNiSn with an Ni-Sn intermetallic phase, and a CoCrFeNi FCC phase. The presence of both the hard intermetallic and this ductile phase helps to resist crack propagation, and consequent material removal during wear. In addition, the high polarization resistance of the passive film formed at the surface and the high corrosion potential of the Ni-Sn phase contribute to preventing chloride corrosion attack during corrosion testing. This film is tenacious enough for the effect to persist under tribocorrosion conditions.

Phase Transition of As-Milled and Annealed CrCuFeMnNi High-Entropy Alloy Powder

NANO ◽  
2018 ◽  
Vol 13 (09) ◽  
pp. 1850100 ◽  
Author(s):  
Rui-Feng Zhao ◽  
Bo Ren ◽  
Guo-Peng Zhang ◽  
Zhong-Xia Liu ◽  
Jian-Jian Zhang
Keyword(s):  
Phase Transition ◽  
Solution Structure ◽  
Milling Time ◽  
Structure Evolution ◽  
High Entropy Alloy ◽  
Chemical Homogeneity ◽  
High Entropy ◽  
Dynamic Phase Transition ◽  
Fcc Phase ◽  
Bcc Phase

The CrCuFeMnNi high entropy alloy (HEA) powder was synthesized by mechanical alloying. The effects of milling time and subsequent annealing on the structure evolution, thermostability and magnetic property were investigated. After 50[Formula: see text]h of milling, the CrCuFeMnNi HEA powder consisted of a major FCC phase and a small amount of BCC phase. The crystallite size and strain lattice of 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were 12[Formula: see text]nm and 1.02%, respectively. The powder exhibited refined morphology and excellent chemical homogeneity. The supersaturated solid solution structure of the as-milled HEA powder transformed into FCC1, FCC2, a small amount of BCC and [Formula: see text] phase in annealed state. Most of the BCC phase decomposed into FCC (mainly FCC2 phase) and [Formula: see text] phases, and the dynamic phase transition was almost in equilibrium at 900[Formula: see text]C. The saturated magnetization and coercivity force of the 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were respectively 16.1[Formula: see text]emu/g and 56.2[Formula: see text]Oe.

Surface hardening of FCC phase high-entropy alloy system by powder-pack boriding

2019 ◽  
Vol 371 ◽  
pp. 389-394 ◽  
Author(s):  
Thomas Lindner ◽  
Martin Löbel ◽  
Benjamin Sattler ◽  
Thomas Lampke
Keyword(s):  
Surface Hardening ◽  
Alloy System ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Fcc Phase

scholarly journals Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1290 ◽  
Author(s):  
Ning Liu ◽  
Chen Chen ◽  
Isaac Chang ◽  
Pengjie Zhou ◽  
Xiaojing Wang
Keyword(s):  
Molar Ratio ◽  
Mixing Enthalpy ◽  
High Entropy Alloy ◽  
Valence Electron Concentration ◽  
Face Centered Cubic ◽  
Distortion Parameter ◽  
Local Lattice Distortion ◽  
Phase Selection ◽  
High Entropy ◽  
Fcc Structure

To study the effect of alloy composition on phase selection in the CoCrCu0.1FeMoNi high-entropy alloy (HEA), Mo was partially replaced by Co, Cr, Fe, and Ni. The microstructures and phase selection behaviors of the CoCrCu0.1FeMoNi HEA system were investigated. Dendritic, inter-dendritic, and eutectic microstructures were observed in the as-solidified HEAs. A simple face centered cubic (FCC) single-phase solid solution was obtained when the molar ratio of Fe, Co, and Ni was increased to 1.7 at the expense of Mo, indicating that Fe, Co, and Ni stabilized the FCC structure. The FCC structure was favored at the atomic radius ratio δ ≤ 2.8, valence electron concentration (VEC) ≥ 8.27, mixing entropy ΔS ≤ 13.037, local lattice distortion parameter α2 ≤ 0.0051, and ΔS/δ2 > 1.7. Mixed FCC + body centered cubic (BCC) structures occurred for 4.1 ≤ δ ≤ 4.3 and 7.71 ≤ VEC ≤ 7.86; FCC or/and BCC + intermetallic (IM) mixtures were favored at 2.8 ≤ δ ≤ 4.1 or δ > 4.3 and 7.39 < VEC ≤ 8.27. The IM phase is favored at electronegativity differences greater than 0.133. However, ΔS, α2, and ΔS/δ2 were inefficient in identifying the (FCC or/and BCC + IM)/(FCC + BCC) transition. Moreover, the mixing enthalpy cannot predict phase structures in this system.

Monocrystalline elastic constants of fcc-CrMnFeCoNi high entropy alloy

MRS Advances ◽  
2017 ◽  
Vol 2 (27) ◽  
pp. 1429-1434 ◽  
Author(s):  
Katsushi Tanaka ◽  
Takeshi Teramoto ◽  
Ryo Ito
Keyword(s):  
Solid Solution ◽  
Elastic Constants ◽  
Room Temperature ◽  
Entropy Change ◽  
High Entropy Alloy ◽  
Melting Points ◽  
High Entropy ◽  
Fcc Metals ◽  
Cauchy Pressure ◽  
Fcc Structure

ABSTRACTMono-crystalline elastic constants of equiatomic quinary Cr-Mn-Fe-Co-Ni high entropy alloy with the fcc structure have experimentally been determined by a resonance ultrasound spectroscopy at room temperature. The values of the bulk modulus of the high entropy alloy experimentally determined are similar to other conventional fcc metals when the values are normalized by the melting points. This indicates that the entropy change at melting is similar to that of conventional metals. The values of Pough’s index and the Cauchy pressure are determined as 1.79 and -11.6 GPa, respectively. When the ductility of the alloy is judged from the indices, the ductility of the high entropy alloy is limited. In order to explain the negative Cauchy pressure of the high entropy alloy, it is required to assume that relatively strong directional interatomic bondings like intermetallic compounds exist in the alloy though the crystal is disordered solid solution.

scholarly journals Effect of Mn Addition on the Microstructures and Mechanical Properties of CoCrFeNiPd High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 288
Author(s):  
Yiming Tan ◽  
Jinshan Li ◽  
Jun Wang ◽  
Hongchao Kou
Keyword(s):  
Intermetallic Compound ◽  
Interface Energy ◽  
High Entropy Alloy ◽  
Strengthening Effect ◽  
Face Centered Cubic ◽  
Liquid Interfaces ◽  
High Entropy ◽  
Single Face ◽  
Face Centered ◽  
Fcc Phase

CoCrFeNiPdMnx (x = 0, 0.2, 0.4, 0.6, 0.8) high entropy alloys (HEAs) were prepared and characterized. With an increase in Mn addition, the microstructures changed from dendrites (CoCrFeNiPd with a single face-centered-cubic (FCC) phase) to divorced eutectics (CoCrFeNiPdMn0.2 and CoCrFeNiPdMn0.4), to hypoeutectic microstructures (CoCrFeNiPdMn0.6), and finally to seaweed eutectic dendrites (CoCrFeNiPdMn0.8). The addition of Mn might change the interface energy anisotropy of both the FCC/liquid and MnPd-rich intermetallic compound/liquid interfaces, thus forming the seaweed eutectic dendrites. The hardness of the FCC phase was found to be highly related to the solute strengthening effect, the formation of nanotwins and the transition from CoCrFeNiPd-rich to CoCrFeNi-rich FCC phase. Hierarchical nanotwins were found in the MnPd-rich intermetallic compound and a decrease in either the spacing of primary twins or secondary twins led to an increase in hardness. The designing rules of EHEAs were discussed and the pseudo binary method was revised accordingly.

scholarly journals A Novel TiZrHfMoNb High-Entropy Alloy for Solar Thermal Energy Storage

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 248 ◽  
Author(s):  
Huahai Shen ◽  
Jianwei Zhang ◽  
Jutao Hu ◽  
Jinchao Zhang ◽  
Yiwu Mao ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Hydrogen Absorption ◽  
Solar Thermal ◽  
High Entropy Alloy ◽  
Solar Thermal Energy ◽  
High Entropy ◽  
Bcc Structure ◽  
Fcc Structure

An equiatomic TiZrHfMoNb high-entropy alloy (HEA) was developed as a solar thermal energy storage material due to its outstanding performance of hydrogen absorption. The TiZrHfMoNb alloy transforms from a body-centered cubic (BCC) structure to a face-centered cubic (FCC) structure during hydrogen absorption and can reversibly transform back to the BCC structure after hydrogen desorption. The theoretical calculations demonstrated that before hydrogenation, the BCC structure for the alloy has more stable energy than the FCC structure while the FCC structure is preferred after hydrogenation. The outstanding hydrogen absorption of the reversible single-phase transformation during the hydrogen absorption–desorption cycle improves the hydrogen recycling rate and the energy efficiency, which indicates that the TiZrHfMoNb alloy could be an excellent candidate for solar thermal energy storage.

scholarly journals Design and Production of a New FeCoNiCrAlCu High-Entropy Alloy: Influence of Powder Production Method on Sintering

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4342
Author(s):  
Eduardo Reverte ◽  
Monique Calvo-Dahlborg ◽  
Ulf Dahlborg ◽  
Monica Campos ◽  
Paula Alvaredo ◽  
...  
Keyword(s):  
Atomic Radius ◽  
Production Method ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
High Entropy ◽  
Powder Production ◽  
Production Techniques ◽  
Fcc Phase ◽  
Domain Iii

The structure of FeCoNiCrAl1.8Cu0.5 high-entropy alloys (HEA) obtained by two different routes has been studied. The selection of the composition has followed the Hume–Rothery approach in terms of number of itinerant electrons (e/a) and average atomic radius to control the formation of specific phases. The alloys were obtained either from a mixture of elemental powders or from gas-atomised powders, being consolidated in both cases by uniaxial pressing and vacuum sintering at temperatures of 1200 °C and 1300 °C. The characterization performed in the sintered samples from both types of powder includes scanning electron microscopy, X-ray diffraction, differential thermal analysis, and density measurements. It was found that the powder production techniques give similar phases content. However, the sintering at 1300 °C destroys the achieved phase stability of the samples. The phases identified by all techniques and confirmed by Thermo-Calc calculations are the following: a major Co-Ni-Al-rich (P1) BCC phase, which stays stable after 1300 °C sintering and homogenising TT treatments; a complex Cr-Fe-rich (P2) B2 type phase, which transforms into a sigma phase after the 1300 °C sintering and homogenising TT treatments; and a very minor Al-Cu-rich (P3) FCC phase, which also transforms into Domain II and Domain III phases during the heating at 1300 °C and homogenising TT treatments.

scholarly journals High Temperature Chloride Corrosion Behavior of 904L:AlFeNiMoNb High-Entropy Alloy

2021 ◽  
Vol 8 ◽  
Author(s):  
Lingyun Bai ◽  
Wenyi Peng ◽  
Dandan Men ◽  
Jun Zhu ◽  
Xuecheng Wu ◽  
...  
Keyword(s):  
Weight Loss ◽  
High Temperature ◽  
Weight Change ◽  
Cost Effective ◽  
Melting Process ◽  
Vacuum Arc ◽  
High Entropy Alloy ◽  
Coating Materials ◽  
High Entropy ◽  
Chloride Corrosion

In order to obtain high cost-effective coating materials working in chlorine-containing environment at high temperature, a 904L super austenitic alloy modified by an AlFeNiMoNb alloy (904L:AlFeNiMoNb) was obtained by vacuum arc melting process. The 904L:AlFeNiMoNb high-entropy alloy has a similar phase component with the AlFeNiMoNb alloy, but a more homogenous microstructure than that of the AlFeNiMoNb alloy. High-temperature chloride corrosion tests for 904L, AlFeNiMoNb, and 904L:AlFeNiMoNb high-entropy alloy were carried out under N2–2.6 vol.% CO2–1.3 vol.% O2–2,700 vppm HCl gaseous environment at 700°C and 800°C for 55 h, respectively. Due to the volatilization of FeCl2, weight change curves of the 904L alloy at 700°C and 800°C showed obvious weight loss. Especially at 800°C, the weight loss of the corroded 904L sample was 10 times that of the corroded sample at 700°C. Different from the weight loss situation of the 904L sample, both AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy showed small weight gains under the corrosion temperature of 700°C, while the latter gained half as much weight as the former. When the corrosion temperature was raised to 800°C, the AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy showed flat weight change curves with little weight loss. Weight loss for the AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy were 1.35138 and 0.0118 mg/cm2, respectively. The high temperature chloride corrosion resistance of 904L:AlFeNiMoNb high-entropy alloy is higher than that of 904L and AlFeNiMoNb at both 700°C and 800°C. Meanwhile, on the basis of the morphology and composition results of the corroded samples, combined with thermodynamic calculation, the high-temperature chloride corrosion mechanics of the tested alloys were discussed.

Effect of the Annealing Treatment on the Microstructure, Microhardness and Corrosion Behaviour of Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys

2013 ◽  
Vol 748 ◽  
pp. 79-85 ◽  
Author(s):  
L.C. Tsao ◽  
C.S. Chen ◽  
Kuo Huan Fan ◽  
Yen Teng Huang
Keyword(s):  
Corrosion Behaviour ◽  
Dendritic Structure ◽  
Annealing Treatment ◽  
Age Hardening ◽  
High Entropy Alloy ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

In this study, an Al0.3CrFe1.5MnNi0.5high entropy alloy was synthesized by arc-melting in Ar. The as-cast alloy ingot was heat treated for 8 h at 650-750°C and then cooled in furnace to investigate the effects of age treatment on the microstructure, hardness and corrosion behaviour. The microstructure of as-cast sample has a typical rich-Cr BCC structure of dendrites, rich-Ni FCC interdendrite phases and a small fraction of cross-like rich-Ni FCC phase within the majority dendritic structure. During annealing treatment at 650°C, the cross-like FCC phase (β-FCC) gradually decreased, dendritic rich-Cr BCC phase transfers to Cr5Fe6Mn8phase, and the AlNi phase precipitated within the matrix dendrites. The interdendritic β1-FCC phases gradually decomposed and transfers to second-phase (β2FCC), and the AlNi precipitated phase coarsen during annealing at 750°C. In addition, Cr5Fe6Mn8phase gradually transfers to rich-Cr BCC phase during slow-cooling process. These precipitation phases in the grain matrix are the main age hardening mechanism. The potentiodynamic polarization of the Al0.3CrFe1.5MnNi0.5high entropy alloys, obtained in 3.5% NaCl solutions, clearly revealed that the corrosion resistance increases and the passive region decreases as annealing temperature increasing.

Sign in / Sign up

Export Citation Format

Share Document