US3793010A - Directionally solidified eutectic type alloys with aligned delta phase - Google Patents

Directionally solidified eutectic type alloys with aligned delta phase Download PDF

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US3793010A
US3793010A US00221165A US3793010DA US3793010A US 3793010 A US3793010 A US 3793010A US 00221165 A US00221165 A US 00221165A US 3793010D A US3793010D A US 3793010DA US 3793010 A US3793010 A US 3793010A
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aluminum
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F Lemkey
E Thompson
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/058—Alloys based on nickel or cobalt based on nickel with chromium without Mo and W

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  • the present invention relates to anisotropic castings resultant from the unidirectional solidification of nickel-(columbium, tantalum)-(chromium, aluminum) eutectic-type alloys.
  • compositions which solidify according to the monovariant eutectic reaction, providing aligned polyphase structures, including such systems as the ternary alloys identified as cobalt-chromiumcarbon and nickel-aluminum-chromium.
  • the advantage of compositions of this nature is that the desired microstructure can be achieved over a range of compositions within a given system. This provides a substantial increase in the freedom of selection of composition permitting increased optimization of properties.
  • application Ser. No. 883,713, now US. Pat. No. 3 ,67 1,223 the concept has been further developed to include those systems solidifying according to the multivariant eutectic reaction where two or more solid phases (n) crystallize simultaneously from a liquid consisting of (n+2) or more components.
  • the present invention relates to eutectic-type alloys within a basic nickel-(columbium, tantalum (chromium, aluminum) system which respond to plane-front solidification to provide phase-aligned-microstructures comprising a lamellar delta phase in a nickel alloy matrix.
  • these alloys are characterized by a nickel alloy matrix containing up to about 35 weight percent chromium and/or up to about 4 weight percent aluminum in solid'solution and about 25-40 volume percent of a lamellar Ni Cb, Ni Ta or Ni (Cb,Ta) delta phase in alignment therein.
  • the alloy as directionally cast, is nominally characterized by a nickel-chromiumaluminum matrix phase containing up to aboutl35 weight percent chromium and up to about 4 weight percent aluminum in solid solution with about 25-40 volume percent of the lamellar delta (8) phase in alignment therein.
  • the as directionally cast alloy is age hardenable through the precipitation of y (a phase based on the intermetallic compound Ni Al) as a dispersed phase in the y matrix.
  • FIG. 1 is a photomicrograph of a longitudinal section of a directionally solidified alloy of the present invention at the monovariant eutectic composition comprising, by weight, 73 percent nickel, 21 percent columbium, and 6 percent chromium (200 X before reduction).
  • FIG. 2 is a similar photomicrograph of another directionally solidified alloy at the monovariant eutectic composition comprising, by weight, '71 percent nickel, 20 percent columbium, and 9 percent chromium.
  • FIG. 3 is a photomicrograph of a longitudinal section of a directionally solidified alloy of the present invention at the monovariant eutectic composition comprising, by weight, 76.4 percent nickel, 20.8 percent columbium, and 2.8 percent aluminum.
  • FIG. 4 is a photomicrograph of a transverse section of a bivariant eutectic composition from the NiCb-- CrAl system wherein 7' phase precipitation has occurred.
  • FIG. 5 is a photomicrograph of a longitudinal section of an alloy at the composition comprising, by weight, 60 percent nickel, 30 percent tantalum and 10 percent chromium, as directionally solidified.
  • FIG. 6 is a graph comprising the liquidus properties in the nickel-columbium-chromium system.
  • FIG. 7 is a graph showing the eutectic troughs and single phase field boundaries in the nickel-rich corner of the nickel-columbium-aluminum diagram.
  • FIG. 8 is a representation showing a polythermal projection of the nickel-columbium-chromium-aluminum diagram which illustrates the bivariant surface wherein the three-phase equilibriumof the type L 'y 8 occurs.
  • FIG. 9 is a graph demonstrating the response of a y 8 monovariant eutectic alloy and a 'y 5 bivariant eutectic alloy to cyclic furnace oxidation at 2,000F, as compared to certain other alloy systems.
  • FIG. 10 is a graph comparing the sulfidation erosion resistance of a bivariant nickel-columbium-chromiumaluminum alloy withother high temperature alloys.
  • the articles to which the present invention has reference are the directionally solidified alloy castings of monvariant or multivariant eutectic composition which display about 25-40 volume percent of an aligned lamellar 6 phase embedded in a 'y matrix.
  • the 8 phase includes not only the Ni Cb and Ni Ta intermet'allic but also, where both colum- I a disc-shaped phase which is believed to be the 7" phase, a tetragonal compound of nickel and columbium.
  • FIGS. 1-3 and 5 show various articles of monovariant ternary eutectic composition as directionally solidified.
  • FIG. 4 is a quarternary nickel-columbium-chromium-aluminum alloy, a preferred embodiment exhibiting bivariant eutectic behavior in solidification. Particular note will be taken in FIG. 4 of the strengthening cuboidal 'y' precipitate in the matrix phase.
  • the articles thus described are those achieved by unidirectional solidification of alloys in the nickel- (columbium, tantalum)-(chromium, aluminum) compositional system exhibiting monovariant or multivariant behavior upon solidification with an aligned 8 phase.
  • the columbium and tantalum appear, generally speaking, to be broadly mutually substitutional or essentially an atomic basis.
  • Either chromium or aluminum or both may be present in the alloy, providing up to about 35 weight percent chromium and up to about 4 weight percent aluminum in the matrix phase as cast.
  • FIG. 6 details the liquidus properties in the nickel-columbium-chromium ternary system while FIG. 7 illustrates the eutectic troughs and single phase field boundaries in the nickel-rich corner of the nickelcolumbium-aluminum diagram.
  • compositions in the quartemary nickel-columbium-chromium-aluminum alloy system of this invention solidify according to the bivariant eutectic reaction, which describes the compositions, defined by a liquidus surface, wherein two solidphases separate from the liquid upon solidification.
  • this surface (shaded in the drawing) will be seen to be bounded by eutectic troughs extending, in the nickel-columbium-chromium system between but exclusive of the binary eutectic NiNi Cb and the ternary eutectic NiCbCr Ni Cb, and, in the nickel-columbium-aluminum system, between but exclusive of the binary eutectic NiNi Cb and the ternary eutectic Ni-Ni AlNi Cb.
  • compositions on the monovariant eutectic troughs have been found to provide the desired phase alignment and characteristic properties.
  • the aligned longitudinal microstructures of the compositions comprising, by weight, 73 percent nickel, 21 percent columbium (297C), and 6 percent chromium, and 71 percent nickel, 20 percent columbium (109C), and 9 percent chromium are shown in FIGS. 1 and 2, respectively.
  • the aligned longitudinal microstructure of a composition comprising, by weight, 76.4 percent nickel, 20.8 percent columbium, and 2.8 percent aluminum, is shown in FIG. 3. That of the alloy comprising, by weight, 60 percent nickel, 30 percent tantalum and 10 percent chromium in longitudinal section is seen in FIG. 5.
  • the 8 phase is Ni Ta and the y phaseis a solid solution of nickel and chromium.
  • the transverse microstructure of the quaternary alloy comprising by weight, 68 percent nickel, 20.6 percent columbium, 9.2 percent chromium andv 2.2 percent aluminum, as shown in FIG. 4, provides clear evidence of the maintenance of the physical aspects of the desired lamellar microstructure.
  • the lamellar Ni Cb(8) phase comprises approximately 30 volume percent of the microstructure.
  • the corrosion resistance in oxidizing atmospheres is strongly or primarily dependent upon the chromium content of the system. Since oxidation of these alloys, as represented by the scaling rate, exhibits a minimum in corrosion susceptibility as the chromium content is varied, biphase alloys in the nickel-chromium-columbium system of a composition defined by the monovariant eutectic trough may be selected to provide the maximum oxidation resistance for a given environment. This flexibility in composition adjustment is inherent in the present invention.
  • chromium and aluminum separately as in the nickel-columbium-chromium and nickel-columbiumaluminum alloys, respectively, or in combination as in the nickel-columbiumchromium-aluminum alloys may significantly improve the oxidation properties.
  • the erosion bar was machined into a tensile specimen such that the area of greatest erosion was within the gage length and tested at 2,000F in air at a strain rate of 0.02 per minute.
  • the ultimate tensile strength and strain to failure were 53,400 psi and 14.2 percent respectively while the strength and failure strain were 52,500 psi and 17.9 percent prior to rig testing.
  • Alloys in the system of the present invention are tolerant of the selected addition of other materials to the basic ternary and quarternary compositions.
  • deviations from or additions to the composition loci defining the monovariant and bivariant eutectic reaction may be made providing, however, that in kind and quantity they do not interfere with the'basic coupled growth mechanism by which the lamellar biphase microstructure is produced.
  • the eutectictype alloys in general, have been found to be tolerant of the addition of sometimes rather substantial quantities of other elements, usually selected to provide or promote the development of a particular property or characteristic in the casting.
  • the solidification rates typically about 05-10 cm/hr, usually associated with the unidirectional solidification of the eutectic-type alloys are also applicable to the present invention.
  • the greater degree of dispersed phase alignment normally occurs in the case of solidification from the ideally planar liquid-solid interface. However, a substantial and, obviously in many cases, satisfactory phase alignment is. also achieved from the cusped interface which may occur at the'higher solidification rates.
  • a directionally solidified alloy casting having an overall composition selected from the group consisting of the monovariant and multivariant eutectic nickelbase alloys solidifying in a polyphase structure consisting of, a 8 phase of the Ni M type where M represents at least one element selected from the group consisting of columbium and tantalum and a 'y phase consisting of a nickel-base alloy containing at least one element selected from the group consisting of chromium and aluminum, and characterized by an anisotropic microstructure having the 8 phase solidified as lamellae in substantial alignment in a matrix consisting essentially of the 7 phase.
  • the 8 phase comprises about 25-40 volume percent of the casting.
  • the y phase is a nickel-base alloy containing at least one element selected from the group consisting of chromium and aluminum in an amount of, as cast, not exceeding, by weight, about 35 percent chromium and about 4 percent aluminum.
  • the 'y phase contains both chromium and aluminum and the y phase, as aged, contains a fine y strengthening phase precipitate.
  • a directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar Ni Cb phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from the group consisting of chromium and aluminum.
  • the Ni Cb phase occupies about-25-40 volume percent of the casting.
  • a directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar Ni Ta phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from group consisting of chromium and aluminum.
  • the Ni Ta phase occupies about 2540 volume percent of the casting.
  • a directionally solidified alloy casting of substantially multivariant eutectic composition characterized by an anisotropic microstructure having about 2540 volume percent of a lamellar Ni M phase, where M is selected from the group consisting of tantalum and columbium, embedded in substantial alignment in a nickel-base alloy matrix containing in solid solution as cast up to 35 weight percent chromium and up to about 4 weight percent aluminum.
  • the matrix phase also contains fine particles of a strengthening 'y precipitate.

Abstract

A nickel alloy containing columbium and/or tantalum and chromium and/or aluminum and displaying eutectic-type behavior is unidirectionally cast under conditions resulting in coupled growth, providing a lamellar biphase or multiphase microstructure displaying about 25-40 percent of a substantially aligned delta phase, Ni3Cb, Ni3Ta or Ni3(Cb,Ta), in a nickel alloy matrix containing chromium and/or aluminum.

Description

United States Patent 1 Lemkey et al.
[ Feb. 19, 1974 DIRECTIONALLY SOLIDIFIED EUTECTIC TYPE ALLOYS WITH ALIGNED DELTA PHASE Inventors: Franklin D. Lemkey; Earl R.
Thompson, both of Glastonbury, Conn.
Assignee: United Aircraft Corporation, East Hartford, Conn.
Filed: Jan. 27, 1972 Appl. No.: 221,165
U.S. Cl 75/170, 75/171, 148/32, 148/32.5 Int. Cl. C22c 19/00 Field of Search 75/170, 171; 148/32, 32.5
[56] References Cited UNITED STATES PATENTS 3,554,817 l/l97l Thompson 148/32 Primary Examiner Richard 0. Dean Attorney, Agent, or Firm-Richard N. James [57] ABSTRACT A nickel alloy containing columbium and/0r tantalum and chromium and/or aluminum and displayingeutectic-type behavior is unidirectiona lly cast under conditions resulting in coupled growth, providing a lamellar biphase or multiphas' microstructure displaying about 25-40 percent of a substantially aligned delta phase, Ni Cb, Ni Ta or Ni (Cb,Ta), in a nickel alloy matrix containing chromium and/or aluminum.
10 Claims, 10 Drawing Figures PATENTED FEB] 9 I974 SHEET 1 BF 8 w w M PAIENTED FEB 1 91974 3.793.010
8HEET3UF8 F'IG.4
PAIENIEB I 3.793.010
' I sum-s 0F 8 I DIRECTIONALLY SOLIDIFIED EUTECTIC TYPE ALLOYS WITH ALIG NED DELTA PHASE BACKGROUND OF THE INVENTION The present invention relates to anisotropic castings resultant from the unidirectional solidification of nickel-(columbium, tantalum)-(chromium, aluminum) eutectic-type alloys.
It is now known that certain eutectic alloys respond to proper unidirectional solidification techniques to produce useful phase-aligned microstructres, as described in the patent to Kraft U.S. Pat. No. 3,124,452. In the patent to Thompson US. Pat. No. 3,554,817, there is described a particularly promising pseudobinary eutectic alloy occurring between the intermetallic compounds Ni,,Al and Ni Cb which responds to plane-front solidification producing a casting characterized by an aligned lamellar microstructure. As so cast, this combination provides the strongest nickelbase alloy known. As is the case with most nickel-base alloys, however, improvements in the oxidation resistance are desired, particularly to permit maximum utilization of the strength characteristics of the alloy in the very high temperature ranges. And even though in its usual application a given alloy may be provided with surface protection for increased oxidation-erosion resistance, improvements in corrosion resistance in the underlying substrate are nevertheless desirable.
In a prior patent of the same inventors, Thompson and Lemkey us. Pat; No. 3,564,940, there is described a class of compositions which solidify according to the monovariant eutectic reaction, providing aligned polyphase structures, including such systems as the ternary alloys identified as cobalt-chromiumcarbon and nickel-aluminum-chromium., The advantage of compositions of this nature is that the desired microstructure can be achieved over a range of compositions within a given system. This provides a substantial increase in the freedom of selection of composition permitting increased optimization of properties. In a copending application of the same inventors filed Dec. 10, 1969, application Ser. No. 883,713, now US. Pat. No. 3 ,67 1,223, the concept has been further developed to include those systems solidifying according to the multivariant eutectic reaction where two or more solid phases (n) crystallize simultaneously from a liquid consisting of (n+2) or more components.
SUMMARY OF THE INVENTION The present invention relates to eutectic-type alloys within a basic nickel-(columbium, tantalum (chromium, aluminum) system which respond to plane-front solidification to provide phase-aligned-microstructures comprising a lamellar delta phase in a nickel alloy matrix. As directionally solidified, these alloys are characterized by a nickel alloy matrix containing up to about 35 weight percent chromium and/or up to about 4 weight percent aluminum in solid'solution and about 25-40 volume percent of a lamellar Ni Cb, Ni Ta or Ni (Cb,Ta) delta phase in alignment therein.
In a preferred composition the alloy, as directionally cast, is nominally characterized by a nickel-chromiumaluminum matrix phase containing up to aboutl35 weight percent chromium and up to about 4 weight percent aluminum in solid solution with about 25-40 volume percent of the lamellar delta (8) phase in alignment therein. In a particular preferred embodiment, the as directionally cast alloy is age hardenable through the precipitation of y (a phase based on the intermetallic compound Ni Al) as a dispersed phase in the y matrix.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a photomicrograph of a longitudinal section of a directionally solidified alloy of the present invention at the monovariant eutectic composition comprising, by weight, 73 percent nickel, 21 percent columbium, and 6 percent chromium (200 X before reduction).
FIG. 2 is a similar photomicrograph of another directionally solidified alloy at the monovariant eutectic composition comprising, by weight, '71 percent nickel, 20 percent columbium, and 9 percent chromium.
FIG. 3 is a photomicrograph of a longitudinal section of a directionally solidified alloy of the present invention at the monovariant eutectic composition comprising, by weight, 76.4 percent nickel, 20.8 percent columbium, and 2.8 percent aluminum.
FIG. 4 is a photomicrograph of a transverse section of a bivariant eutectic composition from the NiCb-- CrAl system wherein 7' phase precipitation has occurred.
FIG. 5 is a photomicrograph of a longitudinal section of an alloy at the composition comprising, by weight, 60 percent nickel, 30 percent tantalum and 10 percent chromium, as directionally solidified.
FIG. 6 is a graph comprising the liquidus properties in the nickel-columbium-chromium system.
FIG. 7 is a graph showing the eutectic troughs and single phase field boundaries in the nickel-rich corner of the nickel-columbium-aluminum diagram.
FIG. 8 is a representation showing a polythermal projection of the nickel-columbium-chromium-aluminum diagram which illustrates the bivariant surface wherein the three-phase equilibriumof the type L 'y 8 occurs.
FIG. 9 is a graph demonstrating the response of a y 8 monovariant eutectic alloy and a 'y 5 bivariant eutectic alloy to cyclic furnace oxidation at 2,000F, as compared to certain other alloy systems.
FIG. 10 is a graph comparing the sulfidation erosion resistance of a bivariant nickel-columbium-chromiumaluminum alloy withother high temperature alloys.
DESCRIPTION OF THE PREFERRED EMBODIMENTS 7 As previously described, the articles to which the present invention has reference are the directionally solidified alloy castings of monvariant or multivariant eutectic composition which display about 25-40 volume percent of an aligned lamellar 6 phase embedded in a 'y matrix. The 8 phase includes not only the Ni Cb and Ni Ta intermet'allic but also, where both colum- I a disc-shaped phase which is believed to be the 7" phase, a tetragonal compound of nickel and columbium.
The 8 phase alignment in these alloys is clearly shown in FIGS. l-S. FIGS. 1-3 and 5 show various articles of monovariant ternary eutectic composition as directionally solidified. FIG. 4 is a quarternary nickel-columbium-chromium-aluminum alloy, a preferred embodiment exhibiting bivariant eutectic behavior in solidification. Particular note will be taken in FIG. 4 of the strengthening cuboidal 'y' precipitate in the matrix phase.
The articles thus described are those achieved by unidirectional solidification of alloys in the nickel- (columbium, tantalum)-(chromium, aluminum) compositional system exhibiting monovariant or multivariant behavior upon solidification with an aligned 8 phase. In this compositional system, the columbium and tantalum appear, generally speaking, to be broadly mutually substitutional or essentially an atomic basis. Either chromium or aluminum or both may be present in the alloy, providing up to about 35 weight percent chromium and up to about 4 weight percent aluminum in the matrix phase as cast.
The general compositional limitations in terms of the melt can best be ascertained by reference to FIGS. 6-8. FIG. 6 details the liquidus properties in the nickel-columbium-chromium ternary system while FIG. 7 illustrates the eutectic troughs and single phase field boundaries in the nickel-rich corner of the nickelcolumbium-aluminum diagram.
The compositions in the quartemary nickel-columbium-chromium-aluminum alloy system of this invention solidify according to the bivariant eutectic reaction, which describes the compositions, defined by a liquidus surface, wherein two solidphases separate from the liquid upon solidification.
Referring to FIG. 8, this surface (shaded in the drawing) will be seen to be bounded by eutectic troughs extending, in the nickel-columbium-chromium system between but exclusive of the binary eutectic NiNi Cb and the ternary eutectic NiCbCr Ni Cb, and, in the nickel-columbium-aluminum system, between but exclusive of the binary eutectic NiNi Cb and the ternary eutectic Ni-Ni AlNi Cb.
Compositions on the monovariant eutectic troughs have been found to provide the desired phase alignment and characteristic properties. The aligned longitudinal microstructures of the compositions compris ing, by weight, 73 percent nickel, 21 percent columbium (297C), and 6 percent chromium, and 71 percent nickel, 20 percent columbium (109C), and 9 percent chromium are shown in FIGS. 1 and 2, respectively. The aligned longitudinal microstructure of a composition comprising, by weight, 76.4 percent nickel, 20.8 percent columbium, and 2.8 percent aluminum, is shown in FIG. 3. That of the alloy comprising, by weight, 60 percent nickel, 30 percent tantalum and 10 percent chromium in longitudinal section is seen in FIG. 5. The 8 phase is Ni Ta and the y phaseis a solid solution of nickel and chromium.
The transverse microstructure of the quaternary alloy comprising by weight, 68 percent nickel, 20.6 percent columbium, 9.2 percent chromium andv 2.2 percent aluminum, as shown in FIG. 4, provides clear evidence of the maintenance of the physical aspects of the desired lamellar microstructure. Within the y matrix there are seen precipitates of both a cuboidal 7, an intermetallic compound based on Ni Al, and a discshaped phase which is believed to be 7" frequently observed in the superalloys containing significant amounts of both aluminum and columbium. As will be noted, the lamellar Ni Cb(8) phase comprises approximately 30 volume percent of the microstructure.
Unidirectionally solidified articles of the Alloy 297C composition, when tested in the direction of phase alignment at both room temperature and at 2,000F, have demonstrated significant strengthening attributable to the aligned microduplex structure. This alloy has exhibited a tensile strength of 171,000 psi at room temperature. The strengths of this alloy solidified at 2 cm/hr and 10 cm/hr were at 2,000F, respectively, 60,200 psi with a failure strain of 6 percent, and 74,400 psi with a failure strain of 8.5 percent. These values of tensile strength approach those reported for the nickelcolumbium-aluminum eutectic system of U.S. Pat. No. 3,554,817, supra, and represent a significant strength increase over the conventional nickel-base superalloy systems. In addition, as hereinafter described in greater detail, additional increases in strength and ductility are attainable by suitable alloy modification within the basic bivariant or multivariant alloy solidification mechanism.
In the nickel-chromium type alloys, the corrosion resistance in oxidizing atmospheres is strongly or primarily dependent upon the chromium content of the system. Since oxidation of these alloys, as represented by the scaling rate, exhibits a minimum in corrosion susceptibility as the chromium content is varied, biphase alloys in the nickel-chromium-columbium system of a composition defined by the monovariant eutectic trough may be selected to provide the maximum oxidation resistance for a given environment. This flexibility in composition adjustment is inherent in the present invention.
Similarly, aluminum is recognized to act beneficially in increasing oxidation resistance of castings. Thus, chromium and aluminum separately as in the nickel-columbium-chromium and nickel-columbiumaluminum alloys, respectively, or in combination as in the nickel-columbiumchromium-aluminum alloys may significantly improve the oxidation properties.
The oxidation properties of eutectic alloys at compositions comprising, by weight, 69 percent nickel, 19 percent columbium, 12 percent chromium having a matrix composition (7) of, by weight, 66 percent nickel, 27 percent chromium, and 7 percent columbium, and 69.9 percent nickel, 20.4 percent columbium, 9.2 percent chromium, 0.5 percent aluminum were ascertained at 2,000F. The results are graphically illustrated in FIG. 9. These alloys are demonstrably superior in terms of their oxidation resistance to both the NiNi Cb and Ni Al Ni Cb eutectic alloys, and compare favorably with the conventional nickel-base superalloys of high corrosion resistance.
- The results of a burner ring thermal cycle test on an alloy test bar at the composition comprising, by weight, 69.7 percent nickel, 20.2 percent columbium, 9.1 percent chromium, and 1.0 percent aluminum together with various other nickel-base super alloys is shown in FIG. 10. The specimens in this test were held in cycles of 1,750F for three minutes followed by heating to 2,050F for two minutes and cooling to 600F while rotating in a jet burner using JP-SR fuel with 3.5 ppm snythetic sea salt operating at Mach 0.3. Besides the excellent relative ranking of the alloy from this test, of as great an interest was the fact that the material suffered no decrease in tensile properties after 219.5 hours of thermal cycling. 'After vane cyclic sulfidation testing the erosion bar was machined into a tensile specimen such that the area of greatest erosion was within the gage length and tested at 2,000F in air at a strain rate of 0.02 per minute. The ultimate tensile strength and strain to failure were 53,400 psi and 14.2 percent respectively while the strength and failure strain were 52,500 psi and 17.9 percent prior to rig testing.
Alloys in the system of the present invention are tolerant of the selected addition of other materials to the basic ternary and quarternary compositions. In general, deviations from or additions to the composition loci defining the monovariant and bivariant eutectic reaction may be made providing, however, that in kind and quantity they do not interfere with the'basic coupled growth mechanism by which the lamellar biphase microstructure is produced. In this respect, the eutectictype alloys, in general, have been found to be tolerant of the addition of sometimes rather substantial quantities of other elements, usually selected to provide or promote the development of a particular property or characteristic in the casting.
A number of ingredients are known to have a profound effect on alloy properties, even though present only in very small amounts. Yttrium and the rare earth elements, for example, in quantities as low as 0.03 weight percent, have been found to promote oxide adherence to the nickel-base superalloys. In some cases, quantities of boron, carbon, hafnium and zirconium have been found to promote creep rupture ductility and, in some cases, cause a pronounced reduction of the tendency of such materials to grain boundary oxidation. As previously mentioned, however, those modifications to the basic ternary or quarternary alloys which provide advantageous results and do not interfere with the development of the desired lamellar microstructure may be included therein. Generally, the solidification rates, typically about 05-10 cm/hr, usually associated with the unidirectional solidification of the eutectic-type alloys are also applicable to the present invention. The greater degree of dispersed phase alignment normally occurs in the case of solidification from the ideally planar liquid-solid interface. However, a substantial and, obviously in many cases, satisfactory phase alignment is. also achieved from the cusped interface which may occur at the'higher solidification rates.
Accordingly, the invention in its broader aspects is not limited to the specific methods, compositions and examples herein described, but numerous modifications, alterations and additions may be madethereto without departing from the true spirit of the invention and without sacrificing its chief advantages.
We claim:
1. A directionally solidified alloy casting having an overall composition selected from the group consisting of the monovariant and multivariant eutectic nickelbase alloys solidifying in a polyphase structure consisting of, a 8 phase of the Ni M type where M represents at least one element selected from the group consisting of columbium and tantalum and a 'y phase consisting of a nickel-base alloy containing at least one element selected from the group consisting of chromium and aluminum, and characterized by an anisotropic microstructure having the 8 phase solidified as lamellae in substantial alignment in a matrix consisting essentially of the 7 phase.
2. A casting according to claim 1 wherein:
the 8 phase comprises about 25-40 volume percent of the casting.
3. A casting according to claim 1 wherein:
the y phase is a nickel-base alloy containing at least one element selected from the group consisting of chromium and aluminum in an amount of, as cast, not exceeding, by weight, about 35 percent chromium and about 4 percent aluminum.
4. A casting according to claim 3 wherein:
the 'y phase contains both chromium and aluminum and the y phase, as aged, contains a fine y strengthening phase precipitate.
5. A directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar Ni Cb phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from the group consisting of chromium and aluminum.
6. A casting as in claim 5 wherein:
the Ni Cb phase occupies about-25-40 volume percent of the casting.
7. A directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar Ni Ta phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from group consisting of chromium and aluminum.
8. A casting as in claim 7 wherein:
the Ni Ta phase occupies about 2540 volume percent of the casting.
9. A directionally solidified alloy casting of substantially multivariant eutectic composition characterized by an anisotropic microstructure having about 2540 volume percent of a lamellar Ni M phase, where M is selected from the group consisting of tantalum and columbium, embedded in substantial alignment in a nickel-base alloy matrix containing in solid solution as cast up to 35 weight percent chromium and up to about 4 weight percent aluminum. I
10. A casting according to claim 9 wherein:
the matrix phase also contains fine particles of a strengthening 'y precipitate.

Claims (9)

  1. 2. A casting according to claim 1 wherein: the delta phase comprises about 25-40 volume percent of the casting.
  2. 3. A casting according to claim 1 wherein: the gamma phase is a nickel-base alloy containing at least one element selected from the group consisting of chromium and aluminum in an amount of, as cast, not exceeding, by weight, about 35 percent chromium and about 4 percent aluminum.
  3. 4. A casting according to claim 3 wherein: the gamma phase contains both chromium and aluminum and the gamma phase, as aged, contains a fine gamma '' strengthening phase precipitate.
  4. 5. A directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar Ni3Cb phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from the group consisting of chromium and aluminum.
  5. 6. A casting as in claim 5 wherein: the Ni3Cb phase occupies about 25-40 volume percent of the casting.
  6. 7. A directionally solidified alloy casting of substantially monovariant eutectic composition characterized by an anisotropic microstructure having a lamellar NI3Ta phase substantially aligned in a nickel-base alloy matrix containing in solid solution an element selected from the group consisting of chromium and aluminum.
  7. 8. A casting as in claim 7 wherein: the Ni3Ta phase occupies about 25-40 volume percent of the casting.
  8. 9. A directionally solidified alloy casting of substantially multivariant eutectic composition characterized by an anisotropic microstructure having about 25-40 volume percent of a lamellar Ni3M phase, where M is selected from the group consisting of tantalum and columbium, embedded in substantial alignment in a nickel-base alloy matrix containing in solid solution as cast up to 35 weight percent chromium and up to about 4 weight percent aluminum.
  9. 10. A casting according to claim 9 wherein: the matrix phase also contains fine particles of a strengthening gamma '' precipitate.
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985582A (en) * 1973-07-30 1976-10-12 Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) Process for the improvement of refractory composite materials comprising a matrix consisting of a superalloy and reinforcing fibers consisting of a metal carbide
US4055447A (en) * 1976-05-07 1977-10-25 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Directionally solidified eutectic γ-γ' nickel-base superalloys
US4288259A (en) * 1978-12-04 1981-09-08 United Technologies Corporation Tantalum modified gamma prime-alpha eutectic alloy
US4409451A (en) * 1981-08-31 1983-10-11 United Technologies Corporation Induction furnace having improved thermal profile
US4543235A (en) * 1982-09-22 1985-09-24 United Technologies Corporation Eutectic superalloy compositions and articles
US4859416A (en) * 1986-03-17 1989-08-22 Stuart Adelman Superalloy compositions and articles
US5649280A (en) * 1996-01-02 1997-07-15 General Electric Company Method for controlling grain size in Ni-base superalloys
US20050025613A1 (en) * 2003-08-01 2005-02-03 Honeywell International Inc. Integral turbine composed of a cast single crystal blade ring diffusion bonded to a high strength disk
US20090136381A1 (en) * 2007-11-23 2009-05-28 Rolls-Royce Plc Ternary nickel eutectic alloy
US11525172B1 (en) 2021-12-01 2022-12-13 L.E. Jones Company Nickel-niobium intermetallic alloy useful for valve seat inserts

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3554817A (en) * 1969-03-20 1971-01-12 United Aircraft Corp Cast nickel-columbium-aluminum alloy

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3554817A (en) * 1969-03-20 1971-01-12 United Aircraft Corp Cast nickel-columbium-aluminum alloy

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985582A (en) * 1973-07-30 1976-10-12 Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) Process for the improvement of refractory composite materials comprising a matrix consisting of a superalloy and reinforcing fibers consisting of a metal carbide
US4055447A (en) * 1976-05-07 1977-10-25 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Directionally solidified eutectic γ-γ' nickel-base superalloys
US4288259A (en) * 1978-12-04 1981-09-08 United Technologies Corporation Tantalum modified gamma prime-alpha eutectic alloy
US4409451A (en) * 1981-08-31 1983-10-11 United Technologies Corporation Induction furnace having improved thermal profile
US4543235A (en) * 1982-09-22 1985-09-24 United Technologies Corporation Eutectic superalloy compositions and articles
US4859416A (en) * 1986-03-17 1989-08-22 Stuart Adelman Superalloy compositions and articles
US5649280A (en) * 1996-01-02 1997-07-15 General Electric Company Method for controlling grain size in Ni-base superalloys
US20050025613A1 (en) * 2003-08-01 2005-02-03 Honeywell International Inc. Integral turbine composed of a cast single crystal blade ring diffusion bonded to a high strength disk
US6969240B2 (en) 2003-08-01 2005-11-29 Honeywell International Inc. Integral turbine composed of a cast single crystal blade ring diffusion bonded to a high strength disk
US20090136381A1 (en) * 2007-11-23 2009-05-28 Rolls-Royce Plc Ternary nickel eutectic alloy
US8858874B2 (en) 2007-11-23 2014-10-14 Rolls-Royce Plc Ternary nickel eutectic alloy
US11525172B1 (en) 2021-12-01 2022-12-13 L.E. Jones Company Nickel-niobium intermetallic alloy useful for valve seat inserts

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BE794412A (en) 1973-05-16
JPS4886725A (en) 1973-11-15
FR2169385B1 (en) 1979-02-23
FR2169385A1 (en) 1973-09-07
CA992357A (en) 1976-07-06
GB1407871A (en) 1975-10-01
CH563461A5 (en) 1975-06-30

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