14parameter calculated for super alloys Ex 1 to Ex 6is higher than the GPRparameter calculated for commercial super alloys Ex 7to Ex 12.[0080]Sensitivity to the formation of TPC (M̅d)[0081]The parameter M̅d is defined as follows:(5)𝑀̅𝑑=∑𝑋𝑖(𝑀𝑑)𝑖𝑛𝑖=15where Xiis the fraction of element i in the superalloy expressed in atomic percent, (Md)iis the value of the parameter Md for element i.[0082]Table3 shows the Mdvalues for the different elements of the superalloys.[0083]Table310ElementMdElementMdTi2.271Hf3.02Cr1.142Ta2.224Co0.777W1.655Ni0.717Re1.267Nb2.117Al1.9Mo1.55Si1.9Ru1.006[0084]Sensitivity to TCPformation is determined by the parameter M̅d, according to the New PHACOMP method which was developed by Morinaga et al.(Morinaga et al., New PHACOMP and its application to alloy design, Superalloys 1984, edited by M Gell et al.,The MetallurgicalSociety15of AIME,Warrendale, PA, USA (1984)pp. 523-532). According to this model, the sensitivity of superalloys to the formation of TCPincreases with the value of the parameter M̅d.[0085]As can be seen in Table2, the superalloys Ex 1 to Ex 12 havevalues of the parameter M̅d approximately equal. These superalloys 20therefore exhibit similarsensitivities to the formation of TCP, sensitivities which are relativelylow.[0086]Phaseγ’solvus temperature.[0087]ThermoCalc software (Ni25 database)based onthe CALPHAD method was used tocalculate the solvus temperature of the γ’phase at 25equilibrium.
15[0088]As can be seen from Table 4, Ex 1 to Ex 6superalloys have a high γ’ solvus temperature comparable to the γ’ solvus temperature of Ex 7to Ex 12commercial superalloys.[0089]Phase γ’ volume fraction [0090]The ThermoCalc software (Ni25 database)based onthe 5CALPHAD method was used tocalculate the volume fraction (volume percent) of phase γ’at equilibrium in superalloys Ex 1 to Ex 12 at 950°C, 1050°C and 1200°C.[0091]As can be seen in Table 4and Figure 3, Ex 1 to Ex 6superalloys contain higher or comparable phase γ’ volume fractions than 10the phase γ’ volume fractions of commercially available Ex 7to Ex12superalloys.[0092]Thus, the combination of high γ’ solvus temperature and highphaseγ’ volume fractionsfor thesuper alloys Ex 1 to Ex 6is favorablefor good creep resistance at high and very high temperatures, for exampleat 151200°C. This resistance must therefore behigher than the creep resistance of commercial superalloys Ex 7to Ex12.[0093]Table 4Tsolvusγ’ (°C)Phase γ’ volume fraction (% vol)950°C1050°C1200°CEx1133867.062.046.0Ex2133567.662.445.9Ex3133766.661.143.2Ex4127660.051.222.7Ex5134465.060.046.0Ex6129558.050.038.0Ex7129058.048.025.0Ex8132063.057.036.0Ex9128360.051.024.0Ex10137465.060.046.0Ex11134868.062.045.0Ex12132167.058.035.0[0094]Volume fraction of TCPtype σ20[0095]The ThermoCalc software (Ni25 database)based onthe CALPHAD method was used tocalculate the volume fraction (in volume
16percent) of equilibrium phase σin superalloys Ex 1 to Ex 12 at 950°C and 1050°C(see Table 5).[0096]The calculated volume fractions of the phase σ are zero at 950°C for Ex 3, Ex 4and Ex 6superalloys, and relatively low for Ex 1 and Ex 5superalloys, reflecting a low sensitivity to TCPprecipitation. These 5results therefore corroborate the results obtained with the New PHACOMP method(parameter M̅d).[0097]Mass concentration of chromium dissolved in the γmatrix[0098]The ThermoCalc software (Ni25 database)based onthe CALPHAD method was used tocalculate the chromium content (in percent 10by mass) in the γphase at equilibrium in superalloys Ex 1 to Ex 12 at 950°C, 1050°C and 1200°C.[0099]As can be seen in Table 5, the chromium concentrations in the γ phase for super alloys Ex 1 to Ex 6are comparable to the chromium concentrations in the γ phase for commercial superalloys Ex 7to Ex12,15which is favorablefor goodcorrosion and hot oxidation resistance.[0100]Table 5Volume fraction of TCPtype σ (in%vol)Chromium content in the γphase (in%by mass)950°C1050°C950°C1050°C1200°CEx 10.40.008.807.806.00Ex20.000.0011.309.907.30Ex 30.00.008.507.605.80Ex 40.00.008.105.504.80Ex 50.70.058.707.906.30Ex 60.00.008.107.005.20Ex 70.70.0012.8010.907.84Ex 81.20.507.406.434.82Ex 91.00.258.377.105.25Ex 100.90.403.623.362.77Ex110.80.207.837.105.70Ex120.40.605.604.803.70[0101]Very high temperature creepproperty
17[0102]Creep tests were carried out on the superalloys Ex 2, Ex 7, Ex 9and Ex 10. Creep tests were carried out at 1200°C and 80 MPa according to the NF EN ISO 204 standard of August 2009 (Guide U125_J).[0103]The results of creep tests in which the superalloys were loaded (80 MPa) at 1200°C are shown in Table 6. The results represent the time 5in hours (h) at specimen failure.[0104]Table 6Time to break (hour)Ex 263Ex 77Ex 99Ex 1059[0105]TheEx 2 superalloyexhibits better creep behaviorthan the Ex 7 and Ex 9superalloys. Ex10 superalloy also has good creep properties.10[0106]Cyclicoxidationproperty at 1150°C[0107]Superalloysshall be thermally cycled as described in INS-TTH-001 and INS-TTH-002: Oxidative Cycling Test Method (Mass Loss Test and Thermal Barrier).[0108]A specimen ofthe superalloy undertest (pin having a diameter 15of 20mm and a height of 1mm) is subjected to thermal cycling, each cycle of which comprises a rise to 1150°C in less than 15 min (minutes), a 60 min stop at 1150°C and turbine-cooling of the specimen for 15 min.[0109]The thermal cycle isrepeated until a loss in mass of the test piece equal to 20 mg/cm² (milligrams per square centimeter) is observed.20[0110]The service life of the superalloystested is shown in Table 7.[0111]Table 7Service life(hours)Ex 2> 1700Ex 7~ 230Ex 8~ 480Ex10~ 100[0112]It can be seen that the Ex 2 superalloyhas a much longer service life than the Ex 7, Ex 8 and Ex 9superalloys. It should benoted 25
18that the oxidation properties ofthe Ex10 superalloy are much poorer than those of the Ex 2superalloy.[0113]Microstructuralstability[0114]After aging for 300 hours at 1050°C, no TCPphase is observed for the Ex 2superalloyby scanning electron microscopy image analysis.5[0115]Sensitivity to foundry defect formation[0116]After forming by the lost-wax process and directional solidification in the Bidgman furnace, no defects resulting from the casting process, particularly of the “freckles”type,were observed intheEx 2superalloy. The“freckles”type defects areobserved after immersion of 10the specimen in a solution based on HNO3/H2SO4.[0117]Although the present disclosurehas been described with reference to a specific example of a specific embodiment, it is obvious that various modifications and changes can be made to these examples without going beyond the general scope of the invention as defined by the 15claims. In addition, individual features of the different embodiments referred to may be combined in additional embodiments. Therefore,the description and drawingsshould be considered in an illustrative rather than restrictive sense.20
19CLAIMS1.Anickel-based superalloy comprising, in percentages by mass, 4.0 to 5.5% rhenium, 1.0 to 3.0% ruthenium, 2.0 to 14.0%cobalt, 0.30 to 1.00%molybdenum, 3.0 to5.0%chromium, 2.5 to 4.0%tungsten, 4.5 to 56.5%aluminum, 0.50to 1.50%titanium, 8.0 to 9.0%tantalum, 0.15 to 0.30%hafnium, 0.05 to 0.15%silicon, the balance being nickel and unavoidableimpurities.2.The superalloy according to claim 1, comprising,in percentages by mass,4.5to5.5% rhenium, 1.0 to 3.0% ruthenium, 3.0 to 5.0% 10cobalt, 0.30to 0.80% molybdenum, 3.0 to 4.5%chromium, 2.5 to 4.0%tungsten, 4.5 to 6.5%aluminum, 0.50 to 1.50%titanium, 8.0 to 9.0%tantalum, 0.15 to 0.30%hafnium, 0.05 to 0.15%silicon,the balance being nickel and unavoidableimpurities.3.The superalloy according to claim 1, comprising,in percentages 15by mass,4.0 to 5.5% rhenium, 1.0 to 3.0% ruthenium, 3.0 to13.0% cobalt, 0.40 to1.00%molybdenum, 3.0 to 4.5%chromium, 2.5 to 4.0%tungsten, 4.5 to 6.5%aluminum, 0.50 to 1.50%titanium, 8.0 to 9.0%tantalum, 0.15 to 0.30%hafnium, 0.05 to 0.15%silicon,the balance being nickel and unavoidableimpurities.204.The superalloy according to claim1, comprising, in percentages by mass,4.0 to 5.0% rhenium, 1.0 to 3.0% ruthenium, 11.0 to 13.0% cobalt, 0.40 to 1.00% molybdenum, 3.0 to 4.5% chromium, 2.5 to 4.0%tungsten, 4.5 to 6.5%aluminum, 0.50 to 1.50%titanium, 8.0 to 9.0%tantalum, 0.15 to 0.30%hafnium, 0.05 to 0.15%silicon,the balance 25being nickel and unavoidableimpurities.5.The superalloy according to claim1, comprising, in percentages by mass,5.0%rhenium, 2.0% ruthenium, 4.0% cobalt, 0.50%molybdenum, 4.0%chromium, 3.0%tungsten, 5.4%aluminum, 1.00% titanium, 8.5% tantalum, 0.25%hafnium, 0.10%silicon,the balance 30being nickel and unavoidableimpurities.6.The superalloy according to claim1, comprising, in percentages by mass, 4.4%rhenium, 2.0% ruthenium, 4.0% cobalt, 0.70% molybdenum, 4.0% chromium, 3.0% tungsten, 5.4% aluminum, 1.00%titanium, 8.5% tantalum, 0.25% hafnium, 0.10% silicon,the balance 35being nickel and unavoidableimpurities.
207.The superalloy according to claim1, comprising, in percentages by mass, 4.4%rhenium, 2.0% ruthenium, 12.0%cobalt, 0.70%molybdenum, 4.0% chromium, 3.0% tungsten, 5.4% aluminum, 1.00%titanium, 8.5% tantalum, 0.25% hafnium, 0.10% silicon,the balance being nickel and unavoidableimpurities.58.The superalloy according to claim1, comprising, in percentages by mass, 5.0% rhenium, 2.0% ruthenium, 4.0% cobalt, 0.50% molybdenum, 3.5%chromium, 3.5%tungsten, 5.4% aluminum, 0.90% titanium, 8.5% tantalum, 0.25% hafnium, 0.10% silicon,the balancebeing nickel and unavoidableimpurities.109.Thesuperalloy according to claim1, comprising,in percentages by mass, 5.0% rhenium, 2.0 ruthenium, 4.0% cobalt, 0.50% molybdenum, 4.0% chromium, 3.5%tungsten, 5.4% aluminum, 0.90% titanium, 8.5% tantalum, 0.25% hafnium, 0.10% silicon, the balance being nickel and unavoidable impurities.1510.The superalloy according to claim1, comprising, in percentages by mass, 4.4%rhenium, 2.0% ruthenium, 12.0% cobalt,0.70%molybdenum, 3.5%chromium, 3.5%tungsten, 5.4% aluminum, 0.90% titanium, 8.5% tantalum, 0.25% hafnium, 0.10% silicon,the balance being nickel and unavoidableimpurities.2011.Asingle-crystal blade (20A, 20B) for a turbomachine comprising a superalloyaccording toany oneof claims 1 to 10.12.Theblade (20A, 20B) according to claim11,comprising a protective coating comprising a metallic bond coatdeposited on the superalloy and a ceramic thermal barrierdeposited on the metallic bond 25coat.13.Theblade (20A, 20B) according to claim11 or 12,having a structure oriented in a<001>crystallographic direction.14.Aturbomachine comprising a blade (20A, 20B) according to any oneof claims10 to13