New Insight into Understanding the Formation of Solid-Solution Multi-Principal Element Alloys

2020 ◽  
Author(s):  
Tsang-Tse Fang
Keyword(s):  
Solid Solution ◽  
Principal Element ◽  
Insight Into

scholarly journals Potential-pH diagrams considering complex oxide solution phases for understanding aqueous corrosion of multi-principal element alloys

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Kang Wang ◽  
Junsoo Han ◽  
Angela Yu Gerard ◽  
John R. Scully ◽  
Bi-Cheng Zhou
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Graphical Representation ◽  
Equilibrium Composition ◽  
Complex Oxide ◽  
Oxidation Products ◽  
Reaction Products ◽  
Aqueous Corrosion ◽  
Principal Element ◽  
Diagram Method

AbstractThe potential-pH diagram, a graphical representation of the thermodynamically predominant reaction products in aqueous corrosion, is originally proposed for the corrosion of pure metals. The original approach only leads to stoichiometric oxides and hydroxides as the oxidation products. However, numerous experiments show that non-stoichiometric oxide scales are prevalent in the aqueous corrosion of alloys. In the present study, a room temperature potential-pH diagram considering oxide solid solutions, as a generalization of the traditional potential-pH diagram with stoichiometric oxides, is constructed for an FCC single-phase multi-principal element alloy (MPEA) based on the CALculation of PHAse Diagram method. The predominant reaction products, the ions in aqueous solution, and the cation distribution in oxides are predicted. The oxide solid solution is stabilized by the mixing free energy (or mixing entropy) and the stabilizing effect becomes more significant as the temperature increases. Consequently, solid solution oxides are stable in large regions of the potential-pH diagram and the mixing free energy mostly affects the equilibrium composition of the stable oxides, while the shape of stable regions for oxides is mostly determined by the structure of the stable oxides. Agreements are found for Ni2+, Fe2+, and Mn2+ between the atomic emission spectroelectrochemistry measurements and thermodynamic calculations, while deviations exist for Cr3+ and Co2+ possibly due to surface complexation with species such as Cl− and the oxide dissolution. By incorporating the solution models of oxides, the current work presents a general and more accurate way to analyze the reaction products during aqueous corrosion of MPEAs.

Formation of Solid Solution and Metallic Nickel Phases During Suspension Plasma Spraying of Co Oxide and Ni Oxide

2021 ◽  
Author(s):  
Vahid Jalilvand ◽  
Ali Dolatabadi ◽  
Christian Moreau ◽  
Saeed Mohammadkhani ◽  
Lionel Roué ◽  
...  
Keyword(s):  
Solid Solution ◽  
Inert Anode ◽  
Metallic Nickel ◽  
Aluminum Production ◽  
X Ray Diffraction ◽  
Oxide Coatings ◽  
Cobalt Nickel ◽  
Sprayed Coatings ◽  
Insight Into

Abstract The focus of this study is the formation of a solid solution and metallic nickel in the cobalt-nickel mixed oxide coatings during suspension plasma spray (SPS) deposition. The (Co,Ni)O solid solution is a potential material for inert anode applications in aluminum production. SPS coatings and in-flight collected particles are studied to gain further insight into the melting and mixing phenomena of the NiO and CoO powders as well as phase formation in the deposited coatings. Moreover, the role of suspension feedstock particle sizes on the microstructure of coatings is discussed. SEM, EDS and X-ray diffraction studies helped better understanding the formation of different crystalline phases within the as-sprayed coatings. It was found that the formation of metallic nickel is possible in the coatings. The results support the importance of substrate temperature on the formation of metallic Ni, so that keeping the substrate at low temperature results in an increase of the Ni content in the coatings. In this study, possible causes for the formation of metallic Ni during spraying are discussed.

scholarly journals New Insight into Phase Formation of MxMg2Al4+xSi5−xO18:Eu2+ Solid Solution Phosphors and Its Luminescence Properties

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Jun Zhou ◽  
Zhiguo Xia ◽  
Mingyue Chen ◽  
Maxim S. Molokeev ◽  
Quanlin Liu
Keyword(s):  
Solid Solution ◽  
Phase Formation ◽  
Luminescence Properties ◽  
Insight Into

scholarly journals Accelerated exploration of multi-principal element alloys with solid solution phases

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
O.N. Senkov ◽  
J.D. Miller ◽  
D.B. Miracle ◽  
C. Woodward
Keyword(s):  
Solid Solution ◽  
Principal Element

Exotic aluminium phosphates, natromontebrasite, brazilianite, goyazite, gorceixite and crandallite from rare-element pegmatites in Namibia

2000 ◽  
Vol 64 (6) ◽  
pp. 1147-1164 ◽  
Author(s):  
J. R. Baldwin ◽  
P. G. Hill ◽  
O. von Knorring ◽  
G. J. H. Oliver
Keyword(s):  
Solid Solution ◽  
Electron Microprobe ◽  
Rare Element ◽  
Magmatic Fluids ◽  
Insight Into

AbstractReplacement phenomena in amblygonite–montebrasite in rare-element pegmatites from the Karibib-Usakos area, Namibia, have been investigated using the electron microprobe. The first African occurrence and analysis of the very rare mineral natromontebrasite NaAl(PO4)(OH,F) is reported from the Daheim pegmatite. In the Okatjimukuju pegmatite, montebrasite has been replaced by a number of phases including crandallite CaAl3(PO4)2(OH)5·H2O and brazilianite NaAl3(PO4)2(OH)4. In one example, montebrasite has been almost completely replaced by brazilianite which has also been found to contain not only crandallite but also its solid solution analogues: goyazite SrAl3(PO4)2(OH)5·H2O and gorceixite BaAl3(PO4)2(PO3OH)(OH)6. Apatite is common at the contacts with montebrasite and associated minerals and texturally is intimately intergrown with crandallite, goyazite and gorceixite at Okatjimukuju. The occurrence of these minerals offers insight into the chemistry of post-magmatic fluids in these pegmatites.

scholarly journals Structural Insight into La0.5Ca0.5Mn0.5Co0.5O3 Decomposition in the Methane Combustion Process

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2283
Author(s):  
Olga Nikolaeva ◽  
Aleksandr Kapishnikov ◽  
Evgeny Gerasimov
Keyword(s):  
Solid Solution ◽  
Catalyst Deactivation ◽  
Combustion Process ◽  
Methane Combustion ◽  
Large Loss ◽  
In Situ Xrd ◽  
Oxide Particles ◽  
Structural Insight ◽  
Insight Into

Perovskite-like solid solution La0.5Ca0.5Mn0.5Co0.5O3 was tested during the total methane combustion reaction. During the reaction, there is a noticeable decrease in methane conversion, the rate of catalyst deactivation increasing with an increase in temperature. The in situ XRD and HRTEM methods show that the observed deactivation occurs as a result of the segregation of calcite and cobalt oxide particles on the perovskite surface. According to the TGA, the observed drop in catalytic activity is also associated with a large loss of oxygen from the perovskite structure.

A tem study of amorphization in Niti irradiated with Ni2+ ions at room temperature

1987 ◽  
Vol 45 ◽  
pp. 220-221
Author(s):  
P. J. Maziasz ◽  
N. H. Packan ◽  
D. F. Pedraza ◽  
E. H. Lee
Keyword(s):  
Solid Solution ◽  
Amorphous Alloys ◽  
Room Temperature ◽  
Crystalline Solid ◽  
Thick Sheet ◽  
Scientific Interest ◽  
The Matrix ◽  
Memory Applications ◽  
B2 Structure ◽  
Insight Into

Irradiation of a crystalline solid solution can cause the decomposition of the matrix into enhanced, modified thermal, or irradiation-induced precipitate phases. Irradiation can also transform the matrix into a new crystalline phase. Alternatively, the heavily irradiated matrix can become amorphous. Alloys of NiTi are intermetallic compounds with shape-memory applications whose amorphization is of both technological and basic scientific interest. Our purpose is to observe some details of the intermediate stages of amorphization to provide further insight into the mechanisms of the phenomenon.An alloy of 50.5 at.% Ni/49.5% Ti was obtained from Raychem Co. as 0.76-mm- thick sheet and then rolled to 0.5 mm sheet. Disks 3 mm in diameter were punched and annealed for 0.5 h at 850°C. This results in an ordered austenitic (B2) structure, which partially transforms to martensite after air quenching.

Solid solution induced back-stress in multi-principal element alloys: Experiment and modeling

2022 ◽  
pp. 142621
Author(s):  
Yongju Kim ◽  
Peyman Asghari-Rad ◽  
Jungwan Lee ◽  
Gang Hee Gu ◽  
Minji Jang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Back Stress ◽  
Principal Element
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