Z. HUDA: ENERGY-EFFICIENT GAS-TURBINE BLADE-MATERIAL TECHNOLOGY – A REVIEW
355–361
ENERGY-EFFICIENT GAS-TURBINE BLADE-MATERIAL
TECHNOLOGY – A REVIEW
TEHNOLOGIJA MATERIALOV LOPATIC ENERGETSKO
U^INKOVITIH PLINSKIH TURBIN – PREGLED
Zainul Huda
King Abdulaziz University, Department of Mechanical Engineering, Jeddah 21589, Saudi Arabia
drzainulhuda@hotmail.com
Prejem rokopisa – received: 2015-07-03; sprejem za objavo – accepted for publication: 2016-02-29
doi:10.17222/mit.2015.196
Energy-efficient gas turbines (GTs) with reduced emissions have significantly contributed to sustainable development. However,
these advanced engines, operating at turbine inlet temperatures (TITs) as high as 1.600 °C, require the development of highly
creep-resistant materials for application in hotter-section components of GTs. This paper first reviews recent advancements in
the development of creep-resistant superalloys and their microstructural control, including stable gamma-prime raft structures.
Then a comparative analysis of recently developed SC superalloys is presented to enable GT designers to select appropriate
materials for hotter energy-efficient GT engines. It is recommended to develop new creep-limited alloys based on the metals
with higher melting temperatures (e.g., Mo and Nb alloyed with silicon); these future alloys are proposed as prospective
candidates for hotter energy-efficient GTs.
Keywords: energy-efficient gas turbines, gas-turbine blades, turbine inlet temperature, single-crystal superalloys
Energetsko u~inkovite plinske turbine (angl. GT) z zmanj{animi emisijami so mo~no prispevale pri trajnostnem razvoju. Vendar
pa ti napredni stroji, ki delujejo pri temperaturah do 1600 °C v vstopnem delu turbine zahtevajo, za uporabo komponent v
vro~em delu, razvoj materialov odpornih na lezenje. ^lanek predstavlja prvi pregled trenutnega napredka pri razvoju na lezenje
odpornih superzlitin in kontrolo njihovih mikrostruktur, vklju~no s stabilno zgradbo gama-prime. Predstavljena je analiza pred
kratkim razvitih SC superzlitin, tako da je konstrukterjem GT omogo~ena izbira primernega materiala za bolj vro~e, energijsko
u~inkovite GT stroje. Predlagan je razvoj novih zlitin z omejenim lezenjem, ki temeljijo na kovinah z vi{jo temperature tali{~a
(npr. Mo in Nb legiran s silicijem); te bodo~e zlitine so predlagane kot perspektivne za bolj vro~e, energijsko u~inkovite GT.
Klju~ne besede: energijsko u~inkovite plinske turbine, lopatice plinskih turbin, vhodna temperatura turbine, monokristalne
superzlitine
1 INTRODUCTION
Modern combined cycle gas-turbine (CCGT) engines
require a significant increase of turbine inlet tempera-
tures (TIT) for achieving the maximum efficiency.1–2
This thermodynamic trend resulted in an increased ser-
vice temperature, enhanced creep damage and hot-corro-
sion attack of the hotter-engine materials.3–4 In particular,
the gas-turbine (GT) blades operate under the most
arduous conditions of temperature and stress of any com-
ponent in the engine. Nickel-based superalloys exhibit an
excellent high-temperature creep resistance, thermal
stability, good tensile strength, long fatigue life, micro-
structural stability at a high temperature as well as good
resistances to oxidation and hot corrosion.5–6 For these
reasons, they are used in the manufacturing of gas tur-
bine hot-section components.7–8
In order to enable energy-efficient gas turbines to
operate at higher TITs, modern CCGTs including ad-
vanced single-crystal (SC) superalloys and special
thermal-barrier coatings (TBCs) should be used.9–10 The
thermal efficiency of such advanced engines involving
closed-loop steam cooling may reach more than 60 %.
The operating temperatures in the first-stage and
second-stage SC blades of modern CCGTs lie in ranges
of 1300–1500 °C and 1000–1100 °C, respectively. For
example, General Electric (GE) Inc., producing USA H
turbines, uses SC materials for first-stage blades and
vanes that operate at a temperature of 1430 °C. Similarly,
first-stage turbine blades of Siemens SGT5-8000H
machines are made of specialized high-temperature alloy
material to combat the long-term effects of high tempe-
ratures at a constant stress (to resist creep deformation).
2 GT-BLADE-MATERIAL TECHNOLOGY
Materials for hot-section components of hotter GT
engines are subjected to very hard operating conditions.
The GT blades, having their walls only a millimeter
thick, whizz around at about 10.000 min–1, while gases
pass across their surface at over 1500 °C. The GT-blade-
material technology progressed in two fronts:
1) GT-blade alloys,
2) thermal barrier coatings (TBCs).
This progress is reviewed in the following sub-
sections.
Materiali in tehnologije / Materials and technology 51 (2017) 3, 355–361 355
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
UDK 67.017:621.438:620.1 ISSN 1580-2949
Review article/Pregledni ~lanek MTAEC9, 51(3)355(2017)
2.1 GT-blade-alloy development
It was established in the preceding section that be-
sides the other important alloy characteristics, the high-
temperature creep resistance is the primary requirement
for the superalloy GT blades of hotter GT engines. The
high-temperature creep strength of the superalloy GT
blades is ensured by the precipitation of a high volume
fraction of fine ’ particles in the material microstruc-
ture.7,11–12 Design principles for developing creep-limited
alloys for the hot sections (particularly blades) of gas
turbines were reported elsewhere.10,13
A number of advanced superalloys have been deve-
loped for GT blades during the recent two decades; these
include single crystal (SC) superalloys (AM1, Rene N6,
MC538, etc), the GTD-111 superalloy, directionally
solidified (DS) GTD-111, the Allvac 718Plus superalloy
and the like.14–18 The IN-738 superalloy remained in use
for the first-stage blades of GT engines during
1971–1984. However, with the development of the
GTD-111 superalloy, IN-738 has now become the
stage-2 blade material.19 A comparative analysis of the
performance of various SC alloys is presented in Section
4, whereas the performance of equiaxed superalloys are
discussed in the following section.
2.2 TBC developments
Thermal barrier coatings (TBCs) play a significant
role in enhancing the energy efficiency since they enable
gas turbines to be operated at higher turbine inlet tem-
peratures (TIT). A TBC is a multi-layer coating consist-
ing of the top coat (ceramic) and the inner layer (the
bond coat) between the ceramic and the substrate.20–21
Recently, R. Kitazawa et al.22 have reported that a tempe-
rature gradient of 150 °C can be achieved using a
ceramic TBC (Y2O3-ZrO2 top coat) on superalloy
components.
Research on the TBC (bond coating) of the GT
blades at Siemens Inc. resulted in a significant improve-
ment in the long-life reliability of turbine blades.23 It was
reported that adding 1–2 % of rhenium (a rare metal with
a high melting temperature and a high density) to a
mixture of cobalt, nickel, chromium, aluminum and
yttrium (the so-called MCrAlY bond coatings) imbues
the complex mixture with extraordinary properties. The
rhenium improves the mechanical properties of the pro-
tective coating and simultaneously prevents the alumi-
num from diffusing into the base material. The coating
system (300-μm-thick bond coating applied directly on
the metal and a thin ceramic layer placed on the top)
stops the base material from oxidizing. Without this
coating system, the nickel-based alloy in the blade would
only survive 4.000 h of operation at the maximum
operating temperatures. With the coating, however, the
alloy can hold out against the oxygen for more than
25.000 h, longer than power-plant operators require as
the minimum.23
3 RECENTLY-DEVELOPED EQUI-AXED
GT-BLADE SUPERALLOYS
Although a number of superalloys have been deve-
loped for GTs, the GTD-111 and the Allvac 718Plus are
the two notable equiaxed superalloys developed for the
GT-blade application in recent years. The effects of the
composition and the heat treatment on the microstruc-
tures and performance of the two GT blade superalloys
are discussed in the following sub-sections.
3.1 GTD-111 superalloy
The GTD-111 superalloy is employed in manufactur-
ing of the first-stage blades of high-power gas turbines.
The chemical composition of the GTD-111 superalloy is
presented in Table 1. The high aluminum and titanium
contents ensure the precipitation of a high volume frac-
tion of the ’ particles in the microstructure promoting a
good creep strength.
The GTD-111 superalloy has a multiphase structure
consisting of the  matrix, ’ precipitate, carbide, –’
eutectic and a small amount of deleterious phases (e.g.,
, , , Laves).15, 16 The superalloy maintains a fairly
Z. HUDA: ENERGY-EFFICIENT GAS-TURBINE BLADE-MATERIAL TECHNOLOGY – A REVIEW
356 Materiali in tehnologije / Materials and technology 51 (2017) 3, 355–361
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Table 1: Chemical compositions of two GT-blade superalloys
Tabela 1: Kemijska sestava dveh superzlitin za lopatice GT
Superalloy % Cr % Co % Ti % W %Al %Ta % Mo % Fe % C % B % Cb % Ni
GTD-111 13.5 9.5 4.75 3.8 3.3 2.7 1.53 0.23 0.09 0.01 - balance
Allvac® 718 Plus 17.9 9 0.74 1.04 1.5 - 2.68 9.3 0.02 0.003 5.51 balance
Figure 1: SEM micrograph showing the primary ’ in the heat-treated
GTD-111 superalloy16
Slika 1: SEM-posnetek primarnih ’ v toplotno obdelani GTD-111
superzlitini16
good tensile-yield strength of 780 MPa with a 10 %
elongation at 700 °C24 (Table 2). Figure 1 shows the
as-standard heat-treated microstructure of GTD-111.17
The alloy obtains its high-temperature creep strength
mainly through the ’ precipitates that are present with a
volume fraction > 60 %. The primary ’ particles have a
cubic shape with the average edge of 0.8 μm. The fine
spherical ’ particles precipitated during the aging treat-
ment have the average diameter of 0.1 μm. The
serrated grain boundaries increase the creep life and
creep plasticity.
3.2 Allvac® 718 Plus™ superalloy
Recently, a new 718Plus nickel-based superalloy has
been developed for the application in energy-efficient
gas-turbine engines allowing an increase in the TIT to a
considerable degree for a high power output. Allvac®
718Plus™ is a novel nickel-based superalloy, designed
for heavy-duty applications in energy-efficient gas turbi-
nes.18
The Allvac® 718Plus™ alloy contains nanometer-
sized spherical ’-phase precipitates (Ni3(Al,Ti)) and
plate-shaped -phase precipitates (Ni3Nb) of a micro-
meter size (Figure 2). The chemical composition of the
Allvac® 718Plus™ superalloy shows higher chromium
(Cr) and molybdenum (Mo) contents as compared to the
GTD superalloy (Table 1). An exceptional feature in the
composition of the Allvac® 718Plus™ alloy is its good
columbium (Cb) content (which is absent in the GTD
alloy). The high Cb content restricts the coarsening of
the ’ particles in the superalloy microstructure ensuring
a long-time creep resistance so as to allow an operation
of a GT engine at a high temperature for longer periods
of time.7,12 A transmission electron micrograph of the
Allvac® 718Plus™ superalloy produced after the aging
at 1148 K for 7800 s shows spherical precipitates of the
’ phase in the  matrix (Figure 2). The aging heat
treatments of the superalloy lead to the precipitation of
intermetallic phases.18
ATI Allvac® has excellent tensile properties at 700
°C25, i.e., y = 1014 MPa and % elongation = 25 (Table
2). It has a comparable tensile strength with a 55 °C tem-
perature advantage over the 718 alloy. It has higher ten-
sile and creep strengths than Waspaloy and a comparable
thermal stability up to at least 704°C. Because of its
good process and metallurgical flexibility, the 718Plus
alloy provides opportunities for special processing such
as fine-grain, mini-grain and superplastic forming, direct
age forging, casting and for large ingot capability.25
Table 2: Tensile-yield strength at 700 °C for three typical GT-blade
superalloys14,24
Tabela 2: Natezna meja plasti~nosti pri 700 °C, treh zna~ilnih lopatic
iz superzlitine za GT14,24
Superalloy SC superalloy:AMI GTD-111
Allvac®
718PlusTM
Yield strength 1.550 MPa 780 MPa 1014 MPa
4 SINGLE-CRYSTAL GT-BLADE SUPERALLOYS
The use of high-pressure turbine blades made of
single-crystal (SC) nickel-based superalloys contributes
efficiently to the continuous performance improvement
of GT engines in terms of power and thermal efficiency.
The employment of directional-solidification (DS)
metallurgy enables us to manufacture single-crystal (SC)
superalloy GT blades with an increased creep resistance
(Figure 3).
SC superalloys have a two-phase microstructure con-
sisting of ’ precipitates coherently embedded in the
-phase matrix as the basic feature (Figure 4), which
allows the outstanding creep resistance of nickel-based
superalloys. Figure 4 shows a transmission-electron
micrograph of a standard heat-treated SC superalloy with
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Materiali in tehnologije / Materials and technology 51 (2017) 3, 355–361 357
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 3: Crystal growth in [001] direction during solidification of a
SC-superalloy blade
Slika 3: Rast kristalnih zrn v smeri [001] med strjevanjem lopatice iz
SC-superzlitine
Figure 2: TEM image of superalloy Allvac® 718Plus™ after aging at
1148 K for 7800 s17
Slika 2: TEM-posnetek superzlitine Allvac® 718Plus™, po staranju
7800 s na 1148 K17
a composition of Ni-9.7Al-1.7Ti-17.1Cr-6.3Co-2.3W %
of the amount fractions. The heat treatment resulted in
the precipitation of nano-sized ‘ precipitates, which are
of cuboidal form and oriented with edges parallel to the
crystallographic directions. Moreover, they are often or-
dered into a three-dimensional grid. Mechanical proper-
ties of these materials depend strongly on the morpho-
logy of the precipitates and, thus, also on the applied
heat treatment.
The microstructure of SC superalloys is convention-
ally studied by transmission electron microscopy (TEM).
The advanced-material-characterization technique for SC
superalloys involves small-angle neutron scattering
(SANS), which yields bulk-averaged information on the
parameters (precipitate shape, size, distance between the
precipitates and volume fraction) of the microstructure.
4.1 Gamma-prime rafting in SC superalloys
Single-crystal nickel-based superalloys with a large
fraction of hardening cuboidal gamma prime (’)
(Figure 4), having a negative misfit if the creep is tested
under a tensile load along the crystalline direction at a
high temperature, can produce a lamellar /’ pattern
perpendicular to the loading axis. This drastic change in
the morphology of ’ is called rafting.25 For a long creep
life of a SC superalloy, it is important that the rafted ’
structure is stable. R. A. Mackay27 reported that direct-
ional coarsening of ’ began during the primary creep,
under certain conditions (at 927–1038 °C) and continued
to develop after the onset of the steady-state creep. The
length of the rafts increased linearly with the time, up to
the plateau region. The thickness of the rafts, however,
remained equal to the initial ’ size, at least up through
the onset of the tertiary creep, which was reported to be a
clear indication of the stability of the finely spaced /’
lamellar structure. It was found that the single crystals
with the finest ’ size exhibited the longest creep lives.
4.2 Comparative analysis of energy-efficient SC super-
alloys
Recently, a new SC Ni-based superalloy has been
jointly developed by the Kansai Electric Power Com-
pany, Co., Inc. (KEPCO), Nagoya Univ. and Hitachi,
Ltd., Japan.28 This SC superalloy contains Ni, Co, Cr, W,
Al, Ti, Ta, Re, Hf, etc. and its microstructure is shown in
Figure 5.
Figure 5 clearly shows the cuboidal morphology of
the ’ precipitates (darker regions) in the  matrix
(brighter regions) of the SC superalloy. Hashizume et al.
reported29 the size of the ’ precipitates to be around 0.4
μm, which is a bit larger than the size reported for
GTD-111 (Section 3.1). However, the significant
beneficial aspect of the microstructure of KEPCO’s SC
superalloy, compared to GTD-111, is the absence of
grain boundaries. Hence, the microstructure of KEPCO’s
SC superalloy (Figure 5) indicates its high-temperature
creep strength, which is also confirmed by the high-tem-
perature capability (>1500 °C) of this superalloy.28 The
chemical compositions of three SC blade superalloys
(AM1, Rene-N6 and MC-534) are reported in Table 2.
Interesting common features of all the three SC
alloys are high W, Al and Ta contents (Table 2). Unique
features of the MC-534 superalloy are its considerable
Re and Ru contents, which impart a remarkable creep
resistance to the alloy (Figure 6). Figure 6 shows the
tensile-creep behavior of the three SC superalloys (AM1,
René N6 and MC-534) at 760 °C/840 MPa; all the three
alloy specimens, tested at orientations within 5° of the
direction,30 are compared.
It is clearly evident from the creep curves in Figure 6
that the SC superalloy MC-534 has the lowest creep
Z. HUDA: ENERGY-EFFICIENT GAS-TURBINE BLADE-MATERIAL TECHNOLOGY – A REVIEW
358 Materiali in tehnologije / Materials and technology 51 (2017) 3, 355–361
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 5: Microstructure of the SC superalloy developed by KEPCO-
HITACHI27
Slika 5: Mikrostruktura SC-superzlitine razvite pri KEPCO-HITA-
CHI27
Figure 4: TEM micrograph showing a large volume fraction of
cuboidal ’ particles in a  matrix of a SC superalloy: Ni-9.7Al-1.7Ti-
17.1Cr-6.3Co-2.3W % of amount fractions
Slika 4: TEM-posnetek ka`e velik dele` kockastih delcev ’ v 
osnovi superzlitine: Ni-9.7Al-1.7Ti-17.1Cr-6.3Co-2.3W atomskih %
strain or deformation as compared to the other two SC
alloys, attributed to the considerable Re and Ru contents
(Table 3). However, the creep-rupture life of AM1 was
reported to be ten times longer than that of the MC-534
alloy.14 Although both MA1 and MC-534 alloys have
similar /’ microstructures, they widely differ in their
chemistries, ’-precipitate sizes and lattice mismatches.
The pronounced and optimum creep-rupture life is ob-
served at 760 °C and 840 MPa, which corresponds to the
’-precipitate size of 480 nm. The low creep-rupture life
of MC-534 can be explained owing to the presence of the
deleterious  phase in the microstructure of the alloy.
Additionally, the excellent tensile-yield strength at 700
°C of the SC superalloy AM1, compared to the other
competitive GT-blade superalloys, is remarkable (Table
2).
5 FUTURE ALLOYS FOR HOTTER GTs
A notable significant development in attaining the
world’s highest thermal efficiency of GT engines was
reported (May, 2011) by Mitsubishi Heavy Industries,
Ltd. (MHI), Japan, with respect to achieving the world’s
highest TIT of 1600 °C with the company’s most
advanced "J-Series" gas turbine, attaining a gross ther-
mal efficiency of over 60 % – the world’s highest level in
the CCGT applications.31 The most advanced J-Series
GT uses a SC nickel-based superalloy.
Future GT manufacturers will demand alloys with an
excellent high-temperature creep resistance, microstruc-
tural stability and castability, along with cost effective-
ness. In view of the alloying of advanced SC superalloys
with refractories and rare metals (e.g., Co, Cr, W, Ti, Ta,
Re, Ru, Hf, etc.) (Table 3), the cost of the production has
risen significantly. This economic constraint requires
research to produce future cost-effective superalloys
without significantly sacrificing the long-life reliability.
Reed et al. 32 reported on alloy-design rules for the SC
superalloys, which allow a very large composition range
for just a few ideal compositions to render them cost
effective. Another notable development in the production
of cost-effective energy-efficient superalloys has recently
been made by Hitachi Inc., who reported to reduce the
material cost by 1/3 of its previous level by reducing the
use of rare metals and by adopting a unique manufactur-
ing (casting) technology, without compromising the
high-temperature strength, oxidation resistance, long
service life and reliability even in the presence of poly-
crystalline regions, which form, with high probability, in
SC superalloy blades.
The new trend of increasing the Re and Ru contents
in recently developed SC alloys requires more research
in view of both desirable and undesirable effects of the
rare metals on the microstructure and creep behavior of
the alloys. F. H. Latief and K. Kakehi34 reported the
effects of the Re content and crystallographic orientation
on the creep behavior of aluminized Ni-based SC super-
alloys. Although an addition of Re was found to be
generally effective for the creep-strength improvement of
the superalloys, the creep strength was significantly de-
creased in aluminized specimens due to the change in
microstructure under the coating layer caused by the for-
mation of the inter-diffusion zone (IDZ) and substrate-
diffusion zone (SDZ). However, the specimens with the
{100} side surface showed longer creep-rupture lives
than the specimens with the {110} side surface, indi-
cating an anisotropic creep behavior.34
A notable development for future superalloys was
reported by the researchers, who proposed to control the
Cr, Re, and Ru contents for enhancing the creep strength
of the SC superalloys.35–36 An addition of 3 % of the
mass fraction of ruthenium (Ru) was found to improve
the intermediate temperature/intermediate stress-creep
behaviors of the SC Ni-based superalloys; however, the
high-temperature creep strength at the intermediate stress
was not found to be good.35 The reduction in the ’
volume fraction upon the addition of Ru appears to be
the principal cause of its diminishing strengthening con-
Z. HUDA: ENERGY-EFFICIENT GAS-TURBINE BLADE-MATERIAL TECHNOLOGY – A REVIEW
Materiali in tehnologije / Materials and technology 51 (2017) 3, 355–361 359
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 6: Creep curves at 760 °C/840 MPa for three typical SC
superalloys
Slika 6: Krivulje lezenja pri 760 °C/840 MPa treh zna~ilnih SC
superzlitin
Table 3: Chemical compositions of typical SC superalloys8,13,17,28
Tabela 3: Kemijska sestava zna~ilnih SC-superzlitin8,13,17,28
Superalloy % Cr % Co % Ti % W %Al %Ta % Mo % Fe % C % B % Re % Ru % Hf % Ni
SC: AM1 7.8 6.5 1.1 5.7 5.2 7.9 2 - - - - - - balance
SC: René N6 4.5 12 - 5.7 6 7.5 1.1 - 0.05 0.04 5.3 - 0.15 balance
MC-534 4 - - 5 5.8 6 4 - - - 3 4 0.1 balance
tribution at elevated temperatures. A.-C. Yeh et al.36
examined the microstructural stability and creep
resistance of an advanced SC superalloy, which had high
contents of Cr (4.6 % of mass fraction), Re (6.4 % of
mass fraction) and Ru (5.0 % of mass fraction).
Experimental results showed that high Re + Ru con-
tents could promote the formation of the hexagonal 
phase at 900 °C; additional Cr and Re could enhance the
precipitation of the TCP phase at 1100 °C. Although an
increase in the lattice misfit between  and ’ in the
investigated SC superalloy could strengthen the alloy
against the creep deformation due to high temperatures
(1000 °C) and low stresses (245 MPa), the micro-
structural stability remained the same. The tendency to
raft should be avoided during the creep at lower
temperatures and higher stresses.36
Although the advanced alloys used in modern GTs
are nickel-based, the tremendous research on the
energy-efficient GTs operating at higher TITs (> 1,600
°C) requires the development of new alloys with greater
temperature capabilities for future applications. These
new alloys should be based on metals with higher melt-
ing temperatures (e.g., molybdenum (Mo) and colum-
bium (Cb) alloyed with silicon) that can be prospective
candidates for hotter GT engines.8 This future trend is
also evident in Figure 7, which illustrates the develop-
ment of advanced superalloys with respect to the tem-
perature capacity of the alloys since 1940.
Figure 7 not only focuses on nickel-based super-
alloys for gas-turbine engine applications, but also de-
monstrates the need for developing new energy-efficient
superalloys, such as Mo-based superalloys for achieving
further technological gains.
6 CONCLUSIONS AND RECOMMENDATIONS
Having reviewed the recent advances in the
GT-blade-material technology, it is recommended to
integrate the latest efficiency-improvement techniques
with the advanced superalloy technologies to enhance
the efficiency and power output in modern industrial gas
turbines. Recently developed equiaxed superalloys (e.g.,
Allvac® 718Plus, GTD-111, etc.) and various SC alloys
(with high Re, Ru and Cr contents) should be com-
paratively analyzed and selected for the hot-section
component of a modern GT engine, with the aid of the
data presented in the paper. In view of the latest deve-
lopment in the GT technology, which enables an ope-
ration at TIT = 1600 °C, it is recommended to develop
superalloys based on higher melting temperatures (such
as molybdenum-based superalloys) for future CCGT
plants with a possibility of operating at TIT > 1600 °C.
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