Phase relation and microstructure in multi-phase intermetallic alloys based on Ni3Al–Ni3Nb–Ni3V pseudo-ternary alloy system

Soga, Wataru; Kaneno, Yasuyuki; Takasugi, Takayuki

doi:10.1016/j.intermet.2005.05.002

Cited by 49 publications

(34 citation statements)

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“…[6][7][8][9][10][11][12][13][14] Among so far studied multi-phase intermetallic alloys, dual two-phase intermetallic alloys composed of Ni 3 Al and Ni 3 V (D0 22 ) have been reported to display good mechanical and chemical properties, and therefore are promising as a next generation type of high temperature structural materials. [8][9][10][11][12][13][14] The dual-two phase intermetallic alloys are composed of ''upper two-phase microstructure'' with a micron scale and ''lower two-phase microstructure'' with a sub micron scale. According to the observed phase diagrams, 7,12) the ''upper two-phase microstructure'' composed of primary Ni 3 Al precipitates and Ni solid solution (A1 phase) is formed at high temperature via A1 mono-phase microstructure after solidification.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb and Ti Addition on Microstructure and Hardness of Dual Two-Phase Intermetallic Alloys Based on Ni3Al-Ni3V Pseudo-Binary Alloy System

et al. 2010

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The microstructures and hardness property of dual two-phase intermetallic alloys that are composed of various kind of volume fractions of geometrically closed packed (GCP) Ni 3 Al(L1 2 ) and Ni 3 V(D0 22 ) phases was studied. Higher volume fraction of primary Ni 3 Al precipitates was observed in the Ti and Nb added alloys when keeping Al content the same. Also, the microstructures in the eutectoid (channel) region consisting of Ni 3 Al+Ni 3 V were sensitive to alloying addition. The hardness of dual two-phase intermetallic alloys was basically explained by mixture rule in hardness between primary Ni 3 Al precipitates and eutectoid region. Nb and Ti addition raised hardness of dual two-phase intermetallic alloys by solid solution hardening in the constituent phases. This hardening was more significant in Nb addition than in Ti addition. In addition to hardness owing to the mixture rule, additional hardening arising from interfacial area between primary Ni 3 Al precipitates and eutectoid region was found. With increasing Ni 3 Al/channel (eutectoid) interfacial area, the additional hardening increased. As temperature increases, the additional hardening monotonously decreased for the base and Nb added alloys but little decreased for the Ti added alloys.

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Section: Introductionmentioning

confidence: 99%

Effect of Nb and Ti Addition on Microstructure and Hardness of Dual Two-Phase Intermetallic Alloys Based on Ni3Al-Ni3V Pseudo-Binary Alloy System

et al. 2010

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“…On the contrary, in the literature there prevail ideas that in multi-component alloys, superalloys in particular, multi-component chemical compounds are formed. As mentioned above, the authors [23,35,56] considered phase transitions taking place in these diffusion couples as occurring similarly to phase transitions in the corresponding binary alloys of the Ni-Mo, Ni-Co and Mo-Co systems [71]. Phase transitions in the binary alloys of the Ni-Mo, Ni-Co and Mo-Co systems have already been discussed in paragraphs 3.1, 3.6 and 4.1.…”

Section: Model Ni 50 со 25 мо 25 Alloymentioning

confidence: 99%

“…provides a visual representation of the changes occurring with the signs of the chemical interaction energy and temperatures of the phase transition 'ordering-phase separation' in all three diffusion couples existing in the Ni 50 Со 25 Мо 25 alloy [71].…”

Section: Model Ni 50 со 25 мо 25 Alloymentioning

confidence: 99%

“…In the Ni/ Mo diffusion couple, this temperature is close to 1250°C, in the Ni/Co couple -to 600°C [23,35]( in both cases, ordering is observed below these temperatures), whereas in the couple of Co/ Mo, such a transition occurs at a temperature close to the solidus, below which a tendency to phase separation takes place [56]. The scheme shown in figure 40.provides a visual representation of the changes occurring with the signs of the chemical interaction energy and temperatures of the phase transition 'ordering-phase separation' in all three diffusion couples existing in the Ni 50 Со 25 Мо 25 alloy [71].After quenching from the liquid state, in different microscopic sites of the foil, different microstructures can be observed.For example, figure 41 shows round light-color spots observed due to electron microscopic absorption contrast from clusters of cobalt atoms. The conclusion, that they are clusters of precisely cobalt atoms was made here on the basis of the fact that absolutely the same structure was observed in the Ni 3 Co binary alloy after heat treatment at 1200°C (Figure 41, inset) [23].…”

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Chemical Bond in Metallic Alloys: Electron Microscopic Study

Ustinovshikov¹

2017

NSTOA

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Aplastic anemia in systemic lupus erythematosus: A better prognosis acquired aplastic anemia Copyright: © 2016 Pannu and VarmaThe first experimental study to verify the existence of the high-temperature phase separation in alloys of the ironchromium system was undertaken by the example of the Fe-45% Cr alloy [15]. Using the method of TEM, it was found that the microstructure of this alloy after quenching from 1150 -1200°С was similar to that which had been obtained in Reference [14]. However, they interpreted such precipitations as chromium nitrides, i.e., as a kind of an "added" phase formed by the chemical reaction of chromium atoms (from the alloy) with atoms of nitrogen (from the air) during a high temperature heat treatment for quenching. A second study was conducted using the Fe 51 Cr 49 alloy, with the help of Mossbauer spectroscopy [16]. It is obvious that the choice of the method of research in Reference was poor, since it was hardly possible to judge a local phase separation of the alloy by the change of the partial gamma-resonance peaks corresponding to pure iron. Therefore, they did not manage to find the structure of phase separation [16]. Figure 2 shows the iron-rich part of an iron-chromium phase diagram, built on the results of electron microscopic studies of the microstructure of alloys of iron with 20, 30, 40 and 50 wt. % of chromium [17]. From the diagram, it can be seen that in the Fe-Cr system, there occur two phase transitions, in the result of which, for example, the microstructure that has formed as a consequence of the tendency to ordering is dissolving and a microstructure of phase separation is forming in its place (and vice versa). This occurs within the temperature ranges of 1100 -850°C and 600 -550°C (Figure 2) On the basis of these data, it could be concluded that at the level of microstructures, such a phase transition is bound to pass through the stage of the existence of the solid solution in the alloy. The authors have given this phase transition the name "orderingphase separation" [17]. Since the discovery of this transition, 17 binary systems have so far been studied and in 16 of them the transition has been experimentally found. The transition occurs at a temperature, specific for each system, at which the sign of the chemical interaction between atoms of A and B is reversed. It is obvious that the transformation of the microstructure formed as a result of the tendency to ordering into the microstructure formed as a result of the tendency to phase separation, and vice versa, is a consequence of the phase transition ordering -phase separation. The transition itself, that is, the process of changing the sign of the chemical interaction between dissimilar atoms, occurs at the level of changes in the electronic structure of the alloy.Before considering the physical essence of this transition, we would like to decide on the issue of the use of such terms as "ordering energy", "mixing energy", "enthalpy of mixing" and so on. Each of the above terms refers to basically the same no...

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“…[1][2][3][4] However, monolithic Ni 3 X-type intermetallic alloys have some drawbacks, poor ductility at room temperature, low creep strength at high temperature and so on. So-called Nibased dual two-phase intermetallic alloys [5][6][7][8][9][10][11][12][13] based on Ni 3 Al (L1 2 : a = 0.3572 nm) -Ni 3 V (D0 22 : a = 0.3542 nm and c/a = 2.036) pseudo-binary alloy system ( Fig. 1) 14) have a unique microstructure: the alloys with a hypereutectoid alloy composition exhibit a mono-phase microstructure of Ni solid solution (A1 phase) at temperatures below melting point and subsequently a two-phase microstructure of the cuboidal Ni 3 Al phase surrounded by the A1 phase with decreasing temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of Si Addition on Microstructure and Mechanical Properties of Dual Two-Phase Ni3Al and Ni3V Intermetallic Alloys

2016

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The effects of Si addition on the microstructures and mechanical properties of dual two-phase Ni 3 Al and Ni 3 V intermetallic alloys with a composition of Ni 75 Al 9 V 13 Nb 3 (expressed by at%) were investigated, focusing on the substitution manner of Si for Ni, Al or V. Solubility limit of Si in the present microstructure was less than 2 at% Si irrespective of the substitution manner of Si for Ni, Al or V. The eutectoid microstructure in the channel region was degenerated when Si was substituted for V. Third-phase dispersions containing Nb, i.e., Ni 16 Si 7 Nb 6 (G phase: D8a) were present at grain boundaries of the alloys exceeding the solubility limit. In the alloy in which Si was substituted for Ni, unit cell volume of the constituent Ni 3 Al phase increased while that of the constituent Ni 3 V phase little changed. In the alloy in which Si was substituted for Al, unit cell volumes of both phases decreased. The alloys in which Si was substituted for Al or Ni hardened while the alloy in which Si was substituted for V softened. The hardening in the former alloys was attributed to solid solution hardening due to Si substituted for solvent atoms Ni, Al and/or V while the softening in the latter alloy was attributed to the degenerated eutectoid microstructure in the channel region. Also, it was shown that the third-phase dispersions little affected hardness as well as yield strength.

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Phase relation and microstructure in multi-phase intermetallic alloys based on Ni3Al–Ni3Nb–Ni3V pseudo-ternary alloy system

Cited by 49 publications

References 28 publications

Effect of Nb and Ti Addition on Microstructure and Hardness of Dual Two-Phase Intermetallic Alloys Based on Ni<SUB>3</SUB>Al-Ni<SUB>3</SUB>V Pseudo-Binary Alloy System

Effect of Nb and Ti Addition on Microstructure and Hardness of Dual Two-Phase Intermetallic Alloys Based on Ni<SUB>3</SUB>Al-Ni<SUB>3</SUB>V Pseudo-Binary Alloy System

Chemical Bond in Metallic Alloys: Electron Microscopic Study

Effect of Si Addition on Microstructure and Mechanical Properties of Dual Two-Phase Ni<sub>3</sub>Al and Ni<sub>3</sub>V Intermetallic Alloys

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