Phase Equilibria and Microstructure on &amp;gamma;&amp;prime; Phase in Co-Ni-Al-W System

Shinagawa, Kazuya; Omori, Toshihiro; Sato, Jun; Oikawa, Katsunari; Ohnuma, Ikuo; Kainuma, Ryosuke; Ishida, K.

doi:10.2320/matertrans.mer2008073

Cited by 265 publications

(117 citation statements)

References 14 publications

(17 reference statements)

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“…Figure 5 shows the isothermal section at 1173 K and with 30 at% Ni for the quaternary Al-Co-Ni-W system. Symbols represent experimental data of Dmitrieva [19] in Figure 4, and Shinagawa et al [20] in Figure 5. Solid curves are calculated using the present TCNI6, dashed ones by an earlier description present from TCNI4, and dotted ones by the recent description of Cui et al [21].…”

Section: Thermodynamic and Kinetic Modelsmentioning

confidence: 99%

The Development and Validation of a New Thermodynamic Database for Ni-based Alloys ................................... 803

Bratberg¹,

Mao²,

Kjellqvist³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Thermodynamic databases developed using the CALPHAD method has been successfully applied to the modeling and simulation of Ni based superalloys for more than fifteen years. Such databases when combined with suitable software, such as Thermo-Calc, can be used for accelerating alloy design as well as improving understanding of existing alloys in terms of their processing and in-service behavior. Additionally, such databases are also essential to the modeling of microstructural evolution using methods such as phase field or mean field approaches.A new thermodynamic database, TCNI6, has been developed for Ni-based superalloys based on the critical evaluation, using the CALPHAD method, of all the constituent binary systems across their full range of composition and many of the ternary systems containing Ni, as well as a number of other key ternary systems. The database has also been validated where possible against higher order systems as well.Together with the new mobility database, MOBNI3, which contains descriptions for the atomic mobility for respectively the γ (A1), γ' (L1 2 ), α (A2), β (B2) and liquid phases, TCNI6 can be used with software such as DICTRA to predict different kinetic aspects taking all relevant phases into account, e.g. the simulation of interdiffusion across Ni-based coatings.A new user friendly computational tool, TC-PRISMA, which simulates the kinetics of precipitation processes, is demonstrated utilizing these new databases and combined with interface property data. Engineering applications of precipitation modelling are validated against experimental data.

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Section: Thermodynamic and Kinetic Modelsmentioning

confidence: 99%

The Development and Validation of a New Thermodynamic Database for Ni-based Alloys ................................... 803

Bratberg¹,

Mao²,

Kjellqvist³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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“…Moreover, these additions strengthen the grain boundary [11][12][13][14] or modify the volume fraction of c 0 [15]. Shinagawa et al [16] reported the increase in c 0 -phase fraction in the Co-Al-W system with increasing content of Ni. This phenomenon may permit for higher amount of alloying elements, such as Cr, without deterioration of stability of the c 0 -phase [17].…”

Section: Introductionmentioning

confidence: 99%

“…This phenomenon may permit for higher amount of alloying elements, such as Cr, without deterioration of stability of the c 0 -phase [17]. Moreover, the differential scanning calorimetry (DSC) measurements showed increase in the c 0 -solvus temperature with Ni content [16]. Generally, the analyzed group of alloys is relatively new and still insufficiently described in the literature, practically in all technological and research aspects.…”

Section: Introductionmentioning

confidence: 99%

Thermal parameters determination of Co–Al–W as-cast alloy homogenization by DTA analysis

Tomaszewska

Moskal

Migas

et al. 2018

J Therm Anal Calorim

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The c-c 0 Co-based superalloys are newly developed class of refractory alloys which may replace commercial Ni-based superalloys owing to their favorable properties at high temperature. In case of new Co-based superalloys, the heat treatment aims to obtain microstructure composed of appropriate volume fraction of small cuboidal c 0 -Co 3 (Al,W) precipitates within the c-Co matrix. However, due to a high tendency to interdendritic segregations of alloying elements, the alloys based on Co-Al-W system should be normally homogenized before further steps of heat treatment (solutionizing and aging). In this study, thermal analysis was applied for determination of temperature range for primary heat treatment of the Co-9Al-9W (at.%). The differential thermal analysis (DTA) measurements were carried out on the thermal analyzer NETZSCH STA 449 F3 Jupiter. On the base of obtained results, respectively, solvus of c 0 phase and solidus temperatures were determined, as well as the thermal range of Co 3 W (DO 19 ) phase precipitation. As a consequence, the heat treatment without homogenizing (only solution and aging) was proposed as a most suitable way to obtain beneficial microstructure.

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“…Recently, addition of Ni to these cobalt-based superalloys has shown to increase the limit of refractory element content as otherwise these are more susceptible to decomposition and unwanted TCP phase formation at high temperatures [26][27][28][29]. This is mainly due to narrow c 0 phase stability of CoAl-W system, and thus, Ni increases the c 0 phase field and also increases the solvus temperature of the alloy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cr addition on γ–γ′ cobalt-based Co–Mo–Al–Ta class of superalloys: a combined experimental and computational study

et al. 2017

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The present article deals with effect of Cr addition (10 at.%) on the partitioning behavior and the consequent effect on mechanical properties for tungsten-free c-c 0 cobalt-based superalloys with base alloy compositions of Co-30Ni-10Al-5Mo-2Ta (2Ta) and Co-30Ni-10Al-5Mo-2Ta-2Ti (2Ta2Ti). Cr addition leads to a change in the morphology of the strengthening cuboidal-shaped c 0 precipitates to a spherical shape. The site preference of Cr atoms in two alloy systems (with and without Ti) has been experimentally investigated using atom probe tomography with the supportive prediction from first principles DFT-based computations. Cr partitions more to the c matrix relative to c 0 . However, Cr also has a strong effect on the Ta and Mo partitioning coefficient across c/c 0 interfaces. The value of partition coefficient for Mo (K Mo ) becomes \1 with Cr addition to the alloys. Results from ab initio calculations show that the Cr atoms prefer to replace Mo atoms in the sublattice sites of the L1 2 unit cell. The solvus temperature of about 1038 and 1078°C was measured for 10Cr2Ta and 10Cr2Ta2Ti alloy, respectively, and these Cr-containing alloys have very low densities in the range of *8.4-8.5 gm/cm -3 . The 0.2% compressive proof strength of 10Cr2Ta2Ti alloy yields a value of 720 MPa at 870°C, substantially better than most Co-Al-W-based alloys and many of the nickel-based superalloys (e.g., MAR-M-247).

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Phase Equilibria and Microstructure on γ′ Phase in Co-Ni-Al-W System

Cited by 265 publications

References 14 publications

The Development and Validation of a New Thermodynamic Database for Ni-based Alloys ................................... 803

The Development and Validation of a New Thermodynamic Database for Ni-based Alloys ................................... 803

Thermal parameters determination of Co–Al–W as-cast alloy homogenization by DTA analysis

Effect of Cr addition on γ–γ′ cobalt-based Co–Mo–Al–Ta class of superalloys: a combined experimental and computational study

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