New Phacomp and its Applications to Alloy Design

Morinaga, Masahiko; Yukawa, Natsuo; Adachi, Hirohiko; Ezaki, H.

doi:10.7449/1984/superalloys_1984_523_532

Cited by 90 publications

(66 citation statements)

References 10 publications

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“…Following the d-electrons concept, 8,9) the compositional averages of the two d-electrons parameters, Md -and Bo -, were calculated since these are known to be related closely to the phase stability as well as the high temperature strength of nickel-based superalloys. 10) …”

Section: Alloy Compositionmentioning

confidence: 99%

Degradation of High-temperature Oxidation Resistance for Ni-based Alloys by Re Addition and the Optimization of Re/Al Content.

et al. 2003

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High-temperature oxidation tests were conducted with two groups of Ni-based superalloys in order to elucidate the Re effect on oxidation resistance. One group of alloys was the Ni-8Cr-2Ti-10Al-Re system, characterized by 10 mol% Al content. The other group of alloys was the Ni-8Cr-2Ti-15Al-Re system, characterized by 15 mol% Al content. The alloy compositions were chosen with the aid of the d-electrons concept, so that any undesirable phases would not appear in the microstructure. Both cyclic and isothermal oxidation tests were carried out at 1 373 K for a total time of 720 ks. The oxidation resistance decreased clearly with increasing Re content in the 10-Al series alloys, but did not in the 15-Al series alloys. The alloys having a Re/Al ratio (mol%) up to 0.1 exhibited very small mass change by oxidation, so the Re/Al ratio was indeed a good indication for the design of superalloys having a good oxidation resistance.KEY WORDS: Ni-based superalloy; high-temperature oxidation resistance; Re effect. Alloy PreparationButton ingots of the experimental alloys were prepared by arc-melting under the purified Ar gas atmosphere. Each button ingot was cut into pieces and remelted several times in order to get a compositional homogeneity. The ingots then underwent a solution heat treatment followed by aging heat treatments. The heat treatment conditions were determined on the basis of the experimental data obtained from the differential thermal analysis (DTA). As shown in Table 2, two-steps aging processes were adopted in this experiment. Microstructural ObservationThe heat-treated ingots were cut into small specimens. Those specimens were mounted with a conductive filled phenolic mounting compound and the specimen surfaces were polished with abrasive papers and then with alumina powders down to 0.05 mm mesh. Polished surfaces were etched in the 1 : 1 volume% HNO 3 and HCl solution for about 30 sec. The microstructural observation of the etched specimens of all the alloys was made using a scanning electron microscopy (SEM). The volume fraction of the gЈ phase in each alloy was measured by analyzing the SEM image in a conventional way. Oxidation TestsThe specimens for oxidation tests were prepared by cutting each alloy ingot into 10ϫ5ϫ1 mm size, and then the surfaces were polished mechanically using emery papers down to # 600 grits. Two kinds of oxidation tests were employed in this study. One was the cyclic oxidation test, in which the specimen was kept in a furnace at 1 373 K for 72 ks followed by air cooling in each cycle. This thermal cycle was repeated for 10 times, so the total exposure time at 1 373 K was 720 ks. The other was the isothermal oxidation test, in which the specimen was set in a furnace for the exposure to static air at 1 373 K for 720 ks followed by air cooling. This test temperature is much lower than the solution-heat-treatment temperature and is equal to the firststep-aging temperature (see Table 2), and therefore it is considered that the volume fraction and shape of the gЈ phase scarcely vary.The...

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Section: Alloy Compositionmentioning

confidence: 99%

Degradation of High-temperature Oxidation Resistance for Ni-based Alloys by Re Addition and the Optimization of Re/Al Content.

et al. 2003

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“…The solid solubility problem of alloys had been treated by the classical parameters of electronegativity and the atomic radius. The solid solubilities in transition-metal based fcc alloys could be treated quantitatively using the Md parameter, compared with the prediction by Nv 20) . Therefore, Md-PHACOMP had been to be superior to the current Nv-PHACOMP 20) .…”

Section: Introductionmentioning

confidence: 99%

Tensile Properties of Bi Alloys and a Case Study for Alloy Design in Their Application to High Temperature Solders

Choi

et al. 2017

Mater. Trans.

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The s-orbital energy levels (Mk) of some alloying elements in a Bi cluster model were obtained on the basis of the molecular orbital calculation. In contrast, binary Bi-Cu/-Ag/-Zn system alloys with ΔMk of 0.013-0.343 were manufactured and tension-or hardness-tested, where ΔMk was the compositional average of Mk. The ultimate tensile strength and hardness were improved as alloying elements were added and increased in alloys. There was the relation between the ultimate tensile strength, fracture strain or hardness and ΔMk. Further, the compositions of Bi-2.0Ag-0.5Cu (ΔMk: 0.180), Bi-5.0Ag-0.5Cu (ΔMk: 0.379) and Bi-0.25Cu-0.25Sb (ΔMk: 0.044) were proposed as ternary alloys. It is found that the ultimate tensile strength, fracture strain and hardness values of ternary alloys could be also able to predict using their estimation lines obtained from binary Bi system alloys.

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“…The ChS88U alloy composition is analyzed with the aid of the d-electrons concept, so that any undesirable phases do not appear in the alloy [6,7]. It is known that high strength nickel based superalloys have special value …”

Section: Methodsmentioning

confidence: 99%

An Influence of Microstructure on the Mechanical Properties of the Corrosion Resistant Superalloy ChS88U

Monastyrskaia¹,

Петров²,

Beljaev³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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Nickel based corrosion resistant superalloy ChS88U, containing 16 mass % Cr, is widely used as a material of gas turbine components. At present, the ChS88U equiaxed blades have more then 80 000h operating time in industrial gas turbine. An influence of microstructure on the mechanical properties of the ChS88U alloy is investigated, using the samples after cast, heat treatment (HT) and hot isostatic pressing (HIP) + HT. Typical creep-rupture lives of cast + HT and HIP + HT samples at 900 o C/274MPa are 271h and 316h, respectively. Mechanical properties of ChS88U are also compared with those of the ChS70 and In738 alloys. The microstructure of the blade with ChS88U post 30 000h operating time in industrial gas turbine investigated by SEM is given in the paper.

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New Phacomp and its Applications to Alloy Design

Cited by 90 publications

References 10 publications

Degradation of High-temperature Oxidation Resistance for Ni-based Alloys by Re Addition and the Optimization of Re/Al Content.

Degradation of High-temperature Oxidation Resistance for Ni-based Alloys by Re Addition and the Optimization of Re/Al Content.

Tensile Properties of Bi Alloys and a Case Study for Alloy Design in Their Application to High Temperature Solders

An Influence of Microstructure on the Mechanical Properties of the Corrosion Resistant Superalloy ChS88U

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