DESIGNING OF HIGH-RHENIUM SINGLE CRYSTAL NI-BASE SUPERALLOY FOR GAS TURBINE BLADES

Transcription

1 Supers 2008 Roger C. Reed, Kenneth A. Green, Perre Caron, Tmothy P. Gabb, Mchael G. Fahrmann, Erc S. Huron and Shela A. Woodard TMS (The Mnerals, Metals & Materals Socety), 2008 DESIGNING OF HIGH-RHENIUM SINGLE CRYSTAL NI-BASE SUPERALLOY FOR GAS TURBINE BLADES E.N. Kablov, N.V. Petrushn All-Russan Scentfc- Research Insttute of Avaton Materals (VIAM), Rado str, 17, Moscow, , Russa Keywords: nckel-base sngle crystal super, rhenum, desgnng, phase stablty, lattce msft, stress-rupture, ductlty ABSTRACT Chemcal and phase composton for new hgh-rhenum sngle crystal N-base super s computer desgned. The mcrostructure, lquaton coeffcents and msft-factor of sngle crystals as cast condton and after thermal treatment are studed. Hgh-temperature creep tests wthn the temperature range of for hours for sngle crystals of an wth orentaton <001> are carred out and evoluton of ther mcrostructure s studed at creepng. The contaned 9 % Re, has acceptable phase stablty and a hgh stress rupture: =450, =215 MP, =95 MP; densty 9089 kg/m 3. It s shown, that formaton of Re enrched lamellar precptatons of a new phase at prolonged hgh temperature acton has a low nfluence on ductle propertes of sngle crystals of the studed. INTRODUCTION At present some generatons of N-base s for sngle crystal gas turbne castng are developed 1-5. The frst generaton N-base supers contan tradtonal ng elements such as Al, T, Cr, Mo, W, Ta, Nb and Hf. The ng element Re n number of 2-4% and 5-7% (by wt.) respectvely s ntroduced n the compostons of the second and thrd generatons N-base supers. Re contaned N-base supers addtonally ed wth Ru n number of 2-6% are referred to the fourth and ffth generatons. It s qute natural, that the basc ng elements are avalable n varous combnatons for dfferent s condtonally referred to one of the specfed generatons. Each new generaton of sngle crystal N-base supers allows ncreasng n temperature capablty of the blades by C. Postve nfluence of Re on hgh temperature strength of nckelbase s s caused by ncrease n soldus temperature of the, hgh solublty of Re n N - sold soluton and ncrease n the perod of ts crystal lattce, decrease n dffuson coeffcent of ng elements. However at prolonged acton of hgh temperature topologcal close-packed phases (TCP) that can have negatve nfluence on mechancal propertes are formed n Re contaned N-base supers. To stablze phase composton and decrease the probablty of TPC phase precptaton these s are ed wth Ru [6-9]. It can be assumed that from the thermodynamc pont of vew n anyone balanced Re and Ru bearng nckel-base supers avalablty of TPC phases s probable. Not only a chemcal composton but also the knetc factor, namely dffuson of atoms of refractory elements n N sold soluton that are part of TCP phase, determnes the volume fracton of TCP phases n 901 Structure. Re and Ru have low dffuson coeffcent n N [10]. Hgh prce of Ru as ng element refers to ts dsadvantage. The purpose of the artcle s desgnng and an expermental research of a new Re-bearng sngle crystal N-base wth extremely hgh stress rupture n the temperature range of , satsfactory densty and acceptable phase stablty. To ncrease the effcency of a new development a method of computer desgn was used. The bass of ths method are regressve models of composton-property type to calculaton the phase composton and materal propertes (for example, phase volume fracton, chemcal composton of - and phases, the perods of phase crystal lattces, phase transformaton temperatures, stress rupture, thermophyscal propertes etc.) [11]. ALLOY DESIGNING The searchng of a composton for a new sngle crystal N-base super was carred out on the bass of multcomponent system N-Al-Cr-Mo-W-Ta-Co-Re for whch ntal condtons of desgnng were formulated: Re concentraton %, densty of an less than 9 g/cm 3, a volume fracton -phase %, temperature of complete soluton of -phase n sold soluton (solvus ) more than 1320, lack of freckles n the process of drectonal soldfcaton of castngs, "wndow" of thermal treatment more than 20, acceptable phase stablty, etc. (total about 15 condtons). The chosen ng system does not contan n the composton such ng elements as T, Nb, Hf wdely used at development of N-base supers. It s bascally caused by the followng crcumstances. Frst, T, Nb and Hf addtves consderably decreasng n soldus temperature of N-base rase homologous temperature and, hence, dffuson moblty of atoms of components n such wll be hgher. Second, these ng elements reduce temperature of eutectc L+ (pertectc L+) transformaton and promote formaton of nonequlbrum precptatons of eutectc (pertectc) phases at crystallzaton and thus make dffcult complete homogenzaton of -sold soluton wthout rsk of fuson for axes dendrte spaces n sngle crystal castng. In the thrd, negatve nfluence of T, Nb, Hf conssts also n the fact that these elements, havng sgnfcant solublty n -phase, have unfavorable effect on dmensonal msft of the perods of crystal lattces for - and - phases n N-base super (msft) and, hence, morphology of strengthenng partcles for -phase. The algorthm of computer search for a new composton was conssted n the followng. In the chosen ng system the gven concentraton for each of 8 ng elements was broken nto three levels: mnmal, average, maxmal and made a desgn matrx of complete factoral experment such as 2 n type for eght varable factors.

2 Then an estmaton of balanced chemcal composton for all 2 n varants of was carred out that was determned by parameter [12]: E E E E0 0,036A where 0 6,28 n A AC n 1 1 (1) : average atomc mass of the, E E C : average number of valence electrons n the components, A, E and : accordngly atomc mass, number of valence electrons and atomc fracton of -component n the ; n: number of components, ncludng the base wthout takng nto account carbon, boron mcroaddtons, rareearth elements (La, Ce, Y, etc.) and mpurty. Parameter E 0 for (1) s obtaned by a method of regressve analyss of expermental data on phase structure for large group of N-base supers wth varous chemcal compostons. For coordnates E - A parameter E 0 determnes phase boundary of stable state for / structure. Usually commercal N-base supers have E parameter value dffered from E 0 n value named by ng dsbalance for the. Value and sgn determnes the probablty of phase transformaton course wth formaton of undesrable phase of varous type n / structure of the. In s wth large negatve ng dsbalance (E <0) the probablty of carbde formaton such as 6 or TCP phases s great; s where E> 0 have tendency to formaton of phases such as N 3 T (DO 24 ) and N 3 Nb (A 3 ), and also eutectc (pertectc) phases on bass of N 3 Al (L1 2 ); at E=0 the s consdered as balanced on the chemcal composton. The chemcal compound of the was consdered balanced (.e. the had phase structure /) f 0.04 E 0 condton was fulflled. Then, the balanced compostons of the were estmated by New PHACOMP (Md) method [13]. Wth these purpose average values of parameter M d for / and -matrx was determned by formula [13]: Other factors on the bass of whch perspectve composton was chosen were temperature of solvus -phase (T solvus ), temperature of eutectc transformaton (ncpent meltng) (T eut ), number of -phase n the at temperature ~850 (F 0 ) and densty of the (d) etc. (total about 15 condtons). Values of the above characterstcs were determned by the followng models [11]: a ={ (Al) (Cr) (Mo) (W) (Ta) (Co) (Nb) (T) (V) (Re) (Ru) (Hf)}10-10, [m] (3) ={ (Cr) (Mo) (W) (Ta) (Co) (Nb) (T) (V) (Re) (Ru) (Hf)}10-10, [m] (4) F 0 = (Al)+1.07(Cr)1.27(Mo)+0.23(W)+4.96(Ta)+ 0.31(Co)+2.54(Nb)+3.81(T)0.75(Re)3.11(V)+1.87(Hf) 1.91(C)+0.17(Al) (Cr) 2 [%] (5) T eut = (Al)2.45(Cr)10.02(Mo)6.24(W)+ 0.84(Ta)1.11(Co)9.55(Nb)10.34(T)5.41(Re)4.01(V) 87.87(Hf)23.32(C), [ C] (6) d = A (7) In formulas (3)-(7) symbols of chemcal elements desgnate ther concentraton (atomc %) n phases and the ; A : average atomc mass of. The composton (herenafter N1 ) was chosen for expermental studyng. The chemcal composton (wt. %) s gven n table I; n table II the values of some characterstcs of ths receved n the desgnng are gven. Table I. Chemcal composton for desgned N Al Cr Mo W Ta Co Re base RESULTS AND DISCUSSION OF EXPERIMENTS OBTAINING OF SINGLE CRYSTALS n M d C ( Md ) (2) 1 where C : atomc fracton of -element n -sold soluton or n the, (Md) : tabular values of parameter (Md) for ths element, n: number of elements, ncludng an base. For the subsequent studes those compostons were chosen where a phase stablty condton was fulflled: Md (/) <0.975 and Md () < For the chosen phase stable compostons of the physcal and chemcal, structure-phase and hgh temperature strength characterstcs were determned. At that the major factor whch determned a choce of the most perspectve composton among phase-stable compostons, was msft. Parameter = ( )/, (here and : the perods of crystal lattces for - and - phases) determned msft. For a new the msft value should be postve ( > ' ) and, at least, 2 tmes more, n comparson wth ths value for second and thrd generaton sngle crystal N-base super. 902 Expermental studyng of desgned was carred out on sngle crystal samples wth the axal orentaton close to crystallographc drecton <001>. Sngle crystals obtaned by LMC method (Lqud Metal Coolng) wth refractory seeds n UVNK-9 furnace for drectonal soldfcaton. To form an optmum mcrostructure of sngle crystals for the wth homogeneous dstrbuton of cubcal partcles '-phases n matrx the heat treatment ncludng step homogenzaton n the range of temperatures for 26 hours and doublestage ageng at temperatures 1130 /4 hr and 870 /48 hr was carred out. MICROSTRUCTURE AND SEGREGATION COEFFICIENT The obtaned sngle crystals of hgh-rhenum N-base super N1 had well-marked dendrte structure (Fg. 1) after the drectonal soldfcaton. Nonequlbrum eutectc + (Fg. 1b) whch volume fracton makes 5-7 % les n nterdendrte spaces. The sze and morphology of -phase partcles essentally dffer n dendrte

3 Table II. Parameters of structure, propertes and characterstcs of desgned Desgned Expermental Physcal and chemcal characterstcs: d, g/m 3 T solvus., C T eut, C T S, T L Structure-phase characterstcs: F 0, % F eut, % (20), % Phase stablty parameters: Stress rupture: (Md ) (Md) E 100, MP, MPa Note: d densty; solvus solvus '); T eut meltng temperature of nonequlbrum eutectc (+'); T S soldus temperature; T L lqudus temperature; F 0 number of dspersed -phase; F eut number of nonequlbrum eutectc (+');, accordngly 100- and -hours stress rupture at temperature for sngle crystals wth orentaton <001> μm 10 μm a) b) 1 μm 1 μm c) d) Fgure 1. Mcrostructure of N1 sngle crystal wth orentaton <001> (cross-secton) after the drectonal soldfcaton: dendrte structure; b eutectc + n nterdendrte area; c, d -phase partcles n -matrx of dendrte (c) and n nterdendrte area (d) 903

4 and nterdendrte spaces (Fg. 1c, d). In the last ones the partcles of - phase are 3-5 tmes coarser than the partcles n dendrte and have less strct facet. Dmensonal and morphologcal heterogenety of -phase, presence of eutectc + s drect consequence of ng elements mcrosegregaton at the drectonal soldfcaton of the. For a quanttatve estmaton of chemcal mcroheterogenety segregaton coeffcents K were used. The segregaton coeffcents were determned by standard method: Phase rregular-shaped partcles are formed on the subgran boundares between fragments of sngle crystal (Fg. 2b). Segregaton coeffcents of Re and W reduced to 1.8 and 1.3 values respectvely, and concentraton of other ng elements was completely balanced practcally. Probably, t explans nsgnfcant dmensonal heterogenety of -phase n dendrte axes and nterdendrte areas of the heat treated sngle crystal. Cd at C d > C d (8) Cd Cd at C d < C d (9) C d where C d and C d : local concentratons of ng element n nterdendrte areas and axes of dendrte respectvely. At such defnton absolute value of the segregaton coeffcent s always 1 and s postve at straght segregaton when the ng element enrches nterdendrte areas. In case of reverse segregaton the ng elements concentrate n dendrte axes and the factor has mnus sgn. In table III values of ng element concentratons n a materal of axes areas and dendrte axes and desgned by formulas (8) and (9) values of segregaton coeffcents n sngle crystals of N1 after drectonal soldfcaton are gven. One can see the most demonstratve elements wth reverse segregaton n cast are rhenum K Re = 3.4 and tungsten K W = 2.1. Ta and Al has straght segregaton K Ta = 2.0 and K Al = 1.4 respectvely. The other ng elements have mnor segregaton. It s known, that chemcal mcroheterogenety of cast N-base supers predetermnes temperature ntervals of basc phase transformaton at heatng, whch to -phase soluton n -sold soluton, + eutectc meltng and -sold soluton meltng are referred. Temperature values of the specfed phase transformatons for studed N1 are gven n table I. Based on these data the heat treatment mode for sngle crystals of the, n partcular homogenzaton temperature was chosen. The N1 sngle crystal mcrostructure after homogenzaton and double-stage ageng s gven on Fg. 2. At hgh-temperature homogenzaton of the two processes proceed: n the begnnng nonequlbrum eutectc s solved and then dffuson balance of chemcal composton n the lmts of dendrte cells occurs. The formaton of mcropores n the sze of up to 10 mcrons n a) b) 1 μm 10 μm Fgure 2. Mcrostructure of N1 sngle crystal after double-stage ageng: a shape and dstrbuton of -phase partcles n matrx of sold soluton; b decoraton of low angle boundary wth phase rregular-shaped partcles Table III. Local chemcal composton and lquaton factors n sngle crystals of N1 after the drectonal soldfcaton Element content (wt. %) and segregaton coeffcents Analyss ste Cr Mo Al W Co N Re Dendrte axes Interdendrte area K nterdendrte areas s the effect of solvng eutectc. phase partcles got the shape of quas-cubods and quasparalleleppeds at the subsequent double-stage ageng (Fg. 2a), the szes of -phase partcles n nterdendrte areas reman a lttle bt coarser than that of n dendrte axes, STRUCTURE-PHASE CHARACTERISTICS Results of X-ray sngle-crystal dffractometry method for the studed after double-stage ageng are gven on Fg. 3. In these experments / (222) Fe K reflecton and ts dvson nto -, -phase snglet under program Outset s used. Based on these results the perods of crystal lattces for - and

5 -phases and msft have been determned. The values are gven n table 4. And actvaton volume of stress rupture process respectvely; ln value proportonal to entropy member); R unversal gas constant. Dgtal values of coeffcents for equaton (10) are gven n table V. Table V. Equaton coeffcents for stress rupture of N1 Temperature nterval of tests, m n ln U 0, kj/mol, J/(mol MP) Stress rupture curves (average values) for temperatures of 900, and 1100 shown on Fg. 4 (ponts show expermental data) were desgned usng the values of factors for the equaton of stress rupture (10). Fgure 3. X-ray <001> sngle-crystal dffractometry for N1 after double-stage ageng: total (222) FeK - reflecton / and -, - phase snglet Table IV. Perods of crystal lattces for -and -phases, msft and number of -phase n N1,,, % F 0, % nanometer nanometer 0, , ,23 65,3 Two conclusons based on data analyss gven on Fg. 3 and n table IV follow. Frst, the studed has hgh postve msft ( > ), equal to 0.23 % as heat treated condton. Apparently, prmary soluton of Re and Mo n -sold soluton explans the fact. As atomc raduses of Re and Mo are more than these of N and they concentrate bascally n -phase, ther nterference results n ncrease n the perod of a crystal lattce for ths phase to a greater extent than that of -phase, and, hence, causes ncrease n msft. Ths crcumstance favorably nfluences on hgh temperature strength of sngle crystals of N-base supers. Second, based on X-ray reflecton ntensty obtaned separately from - and -phases, to total / reflex ntensty rato t s possble to estmate volume fractons of phases. It has been found that the volume fracton of -phase n N1 as heat treatment condton makes 65.3 %. CREEP RUPTURE STRENGTH Expermental defnton of creep rupture strength for N1 was carred out at temperatures of 900, and 1100 (test perod above hours) on sngle crystal specmens (total length 70 mm, desgned length of a workng part 25 mm at dameter 5 mm) wth crystallographc orentaton <001> (wthn the lmts of the tolerance 10 ). Statstc result manpulaton of creep rupture strength tests was carred out as per equaton [14]: T U exp m n 0 RT (10) where creep-rupture lfe, hour; stress, MP; temperature, ;, m, n, U 0, coeffcents determned based on results of stress rupture tests (U 0 and actvaton energy 905 Stress (MPa) Creep-rupture lfe (hours) Fgure 4. Stress rupture curves for N1 sngle crystal wth orentaton <001> at temperatures of 900 C (1), C (2) and 1100 C (3) Average values of lmts for stress rupture of N1 (n comparson wth characterstcs of s EPM-102 and CMSX-10 are gven n table V. Table V. Stress rupture for Re-bearng sngle crystal N-base supers Alloy, MP N (9 % Re) EPM-102* (6 % Re, 3 % Ru) CMSX-10* (6% Re) *We got values of stress rupture for s EPM-102 and CMSX-10 by processng partcular value of rupture lfe at varous temperatures and stress taken from papers [7, 15]. These results testfy to advantage of N1 n comparson wth thrd and fourth generatons sngle crystal nckel-base supers EPM-102 and CMSX-10 throughout temperaturetme range

6 EVOLUTION OF A MICROSTRUCTURE AT CREEPING Test results of structure studes for materals ruptured by hgh temperature creep test of sngle crystal specmens from N1 are gven on Fg. 5 and 6. So-called raft-mcrostructure ypcal for sngle crystals of N-base supers wth the orentaton <001> subjected to constant tenson at hgh temperatures was observed n the structure at all test modes. Durng a transent stage of hgh-temperature creepng the ntal cubcal partcles of '-phase coagulate specfcally by means of jonng n plates whch wde facets are perpendcular to axes of tenson applyng. Sectons of these plates as consstently alternatng layers - and -phases (accordngly dark and lght layers on Fg. 5) wll be projected on vertcal facets (100) and (010). Such mcrostructure remans ts regularty throughout statonary stage of specmen creepng. The regular raft-mcrostructure shows sgnfcant resstance to plastc creep stran as t nterferes wth crossng of -phase plates by dspostons that move n layers of -sold soluton. In ths sense any regularty dsturbance of raft-mcrostructure wll result n softenng and decreasng n stress rupture. The greatest changes n mcrostructure durng creepng are observed n the materal bulk close to ruptured zone of the specmen. a) b) 1 μm 10 μm Fgure 5. Raft-mcrostructure (a) and deformaton pores (b) formed at hgh temperature creep for sngle crystal of N1 super: C, =1361 hr 10 μm 2 μm a) b) 10 μm 10 μm c) d) Fg.6. Hgh rhenum FCC phase n sngle crystals of N1 super formed at prolonged creep rupture at 1100 (=559 h) (a) and C (=2591 h) (b d): b, c, d after deep chemcal etchng of specmen surface (G.I. Morozova) 906

7 Here the raft-mcrostructure undergoes topologcal nverson,.e. -phase plates jonted durng creepng form one-coherent matrx and earler one-coherent matrx -sold soluton forms layers solated from each other. It s determned that mcropores wth crystallographc facet (deformaton pores) are avalable n the materal of ruptured sngle crystals (Fg. 5b) whch number and sze ncreases as approachng ruptured zone of specmen. After creepng at temperatures of C for ~2600 hours and 1100 C for ~500 hours lamellar precptatons of a new phase (dark thn plates n lght envelope of '-phase) (Fg. 6a, b), penetratng practcally throughout specmen materal bulk are found n the structure. X-ray structure analyss of the wth such mcrostructure has shown that the lamellar phase has face-centered cubc lattce (structural type A1) wth the perod of 0,361 nanometers whereas the perods of lattces for matrx - and - phases are wthn the lmts of 0,358-0,359 nanometers; Re content n lamellar phase makes 20 % (atomc). One can see on Fg. 6b where the surface mcrostructure of the sngle crystal specmen after deep chemcal etchng s shown, hgh rhenum FCC phase n the structure at prolonged hgh temperature tests got a woven structure. Let's consder nfluence hgh rhenum FCC phase on mechancal propertes of N1. Adverse nfluence of classcal TCP phases on mechancal propertes of N-base supers, n partcular, resultng n premature ntaton of mcrocracks and embrttlement s known. However n case of sngle crystals for hgh rhenum N1 t has been found expermentally that avalablty of lamellar precptatons of a new phase has low nfluence on ts ductle characterstcs. Results of studes of mechancal propertes and mcrostructure N1 n varous condtons: after double-stage ageng and prolonged annealng at gven n tables VI VIII and on Fg.7 testfy to ths fact. Table VII. Tensle propertes (20 ) for N1 after double-stage ageng and annealng at Heat treatment Conventonal yeld strength, MP Ultmate strength, MP Relatve elongaton, % Double-stage ageng Annealng: 500 hours The analyss of the expermental data obtaned shows that despte of formaton n N1 materal of a plenty lamellar face-centered cubc phase, value of ductlty of sngle crystals at a short-term tenson, ther servce lfe and stress rupture ductlty at creep test are kept at hgh enough level (tables VI VIII). Hence, lamellar hgh rhenum phase of structural type 1 does not result n embrttlement of sngle crystals of N1 N-base super. However, as one can see n table 8 that at stress rupture test servce lfe of the after annealng at for 500 hours s consderably less, than that of after double-stage ageng (table VI). Comparson of evoluton of phase structure and /'-mcrostructure n sngle crystals of durng prolonged hgh-temperature annealng (Fg. 7) wth results of stress rupture tests for these sngle crystals (table VIII) has shown that the reason of reducton of ther servce lfe s the roughenng and degradaton of partcles of the basc strengthenng of -phase. Table VI. Stress rupture and ductlty of N1 after doublestage ageng T, Tenson, MP Creeprupture lfe, hour Stress rupture ductlty, % * *Specmen s taken off from tests. a) 1 μm 1 μm b) Fgure 7. N1 super mcrostructure after annealng at temperature : a 200 h; b 500 h Table VIII. Stress rupture and ductlty for N1 after annealng at temperature T, Tenson, Annealng 200 h Annealng 500 h MP Stress-rupture lfe, h Stress rupture ductlty, % Stress-rupture lfe, h Stress rupture ductlty, %

8 CONCLUSIONS 1. On the bass of phase structure desgnng, physcal and chemcal and structure - phase characterstcs of nckel-base s for system N-Al-Cr-Mo-W-Ta-Co-Re we desgned the new sngle crystal super contanng 9 % Re. To mprove phase stablty the total contents of refractory (Re, Mo, Ta, W) and -formed (Al, Ta) elements n the was balanced. 2. Developed hgh rhenum VJZM-1 has advantage on stress rupture n the feld of workng temperatures and servce lfe over thrd and fourth generatons CMSX-10 and EPM-102 sngle crystal N-base supers. 3. At prolonged heatng or creepng n temperature range of lamellar precptatons of face-centered cubc phase enrched wth Re and havng the perod of crystal lattce equal to 0,361 nanometers are formed. It has been founded that ths phase does not negatve nfluence on stress rupture ductlty of the sngle crystals. ACKNOWLEDGEMENTS Authors thank dr. G.I. Morozova, dr. A.I. Samoylov and dr. V.V. Gerasmov for ther help and frutful dscusson durng fulfllment of the work. REFERENCES 9. K.S. O Hara, W.S. Walston, E.W. Ross and Darola R., Nckel base super and artcle, US Patent , January 9, Chong Long Fu, Roger Reed, Anderson Janott and Maja Kremar, On the dffuson of ng elements n the nckelbase supers, n Supers 2004, ed. K.A. Green et al. Champon (Pennsylvana): Publ. of the Mnerals, Metals & Materals Socety. Seven Sprngs Mountan Resort, 2004, E.N Kablov and N.V. Petrushn, Computer method of desgnng castng nckel-base supers, n Castng Supers: Kshkn s Effect (Moscow, Nauka), 2006, G.I. Morozova, Formaton of the chemcal composton of the '/ matrx of multcomponent nckel s, Dokl. Akad. Nauk SSSR, 320, N6 (1991), N. Yukawa, M. Mornaga, H. Ezak and Y. Murata, Alloy desgn of supers by the d-electrons concept, Hgh Temp. Alloys for Gas Turbnes and Other Applcatons. Proc. of Conf. Lege (Belgum, 6-9 October 1986). Dordrecht: C.R.M., 1986, E.N. Kablov and E.R. Golubovsky, Hgh-Temperature Strength of Nckel Alloys, (Moscow, Mashnostroene) 1998, G.L. Erckson, Sngle crystal nckel-based super CMSX-10, US Pat Nov. 22, G.L. Erckson and K. Harrs, DS and SX supers for ndustral gas turbnes, Materals for Advanced Engneerng: Proc. of Conf. Part II, Lege (Belgum), 3-4 Oct. 1994, G.L. Erckson, The development and applcaton of CMSX-10, n Supers 1996, ed. R.D. Kssnger et al. Publ. of the Mnerals, Metals & Materals Socety. Seven Sprngs Mountan Resort, Champon (Pennsylvana), 1996, P. Caron and T. Khan, Thrd generaton supers for sngle crystal blades, Hgh Temp. Mater. for Power Engneerng: Proc. Conf. Part II, Lege (Belgum). Germany: Ferschungszentrum Jlch Gmbh, 1998, H. Hno, Yoshoka Y., Nagata K. et al., Desgn of hgh Re contanng sngle crystal supers for ndustral gas turbnes. Materal for Advanced Power Engneerng, Hgh Temperature Materals for Power Engneerng 1998: Proc. of Conf. Part II, Lege (Belgum). Germany: Forschungszentrum, Julch Gmbh, 1998, E.N. Kablov and N.V. Petrushn, Physcochemcal and Technologcal Features of Creatng Metal-Based Hgh- Supers, Pure Appl. Chem., 76, N.9 (2004), P. Caron, Hgh solvus new generaton nckel-based supers for sngle crystal turbne blade applcatons, n Supers 2000, ed. T.M. Pollock et al., Champon (Pennsylvana): Publ. of the Mnerals, Metals & Materals Socety. Seven Sprngs Mountan Resort, 2000, S. Walston, A. Cetel, R. MacKay et al., Jont development of a fourth generaton sngle crystal super, n Super 2004, ed. K.A. Green et al., Champon (Pennsylvana): Publ. of the Mnerals, Metals & Materals Socety. Seven Sprngs Mountan Resort, 2004, Y. Kozum, T. Kobayash, T. Yokokawa et al., Development of next-generaton N-base sngle crystal supers, n Supers 2004, ed. K.A. Green et al., Champon (Pennsylvana): Publ. of the Mnerals, Metals & Materals Socety. Seven Sprngs Mountan Resort, 2004,

9