US20160010186A1 - Aluminum-molybdenum-zirconium-tin master alloys - Google Patents
Aluminum-molybdenum-zirconium-tin master alloys Download PDFInfo
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- US20160010186A1 US20160010186A1 US14/772,675 US201414772675A US2016010186A1 US 20160010186 A1 US20160010186 A1 US 20160010186A1 US 201414772675 A US201414772675 A US 201414772675A US 2016010186 A1 US2016010186 A1 US 2016010186A1
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- molybdenum
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- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 64
- 239000000956 alloy Substances 0.000 title claims abstract description 64
- -1 Aluminum-molybdenum-zirconium-tin Chemical compound 0.000 title claims abstract description 12
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 53
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 52
- 239000011733 molybdenum Substances 0.000 claims abstract description 52
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 19
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000010936 titanium Substances 0.000 claims abstract description 18
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 18
- 238000002844 melting Methods 0.000 claims abstract description 17
- 230000008018 melting Effects 0.000 claims abstract description 17
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 15
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 15
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims description 27
- 239000003832 thermite Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 abstract description 4
- 238000005275 alloying Methods 0.000 abstract description 2
- 239000011819 refractory material Substances 0.000 abstract description 2
- 229910052718 tin Inorganic materials 0.000 description 10
- 238000007711 solidification Methods 0.000 description 7
- 230000008023 solidification Effects 0.000 description 7
- 229910001069 Ti alloy Inorganic materials 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- VOXZDWNPVJITMN-ZBRFXRBCSA-N 17β-estradiol Chemical compound OC1=CC=C2[C@H]3CC[C@](C)([C@H](CC4)O)[C@@H]4[C@@H]3CCC2=C1 VOXZDWNPVJITMN-ZBRFXRBCSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910015455 Mo3Al Inorganic materials 0.000 description 2
- 229910000883 Ti6Al4V Inorganic materials 0.000 description 2
- 238000001636 atomic emission spectroscopy Methods 0.000 description 2
- 238000012864 cross contamination Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910016027 MoTi Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/04—Alloys containing less than 50% by weight of each constituent containing tin or lead
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/003—Alloys based on aluminium containing at least 2.6% of one or more of the elements: tin, lead, antimony, bismuth, cadmium, and titanium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/04—Alloys based on tungsten or molybdenum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
Definitions
- the present invention relates to titanium base alloys, and more particularly to aluminum-molybdenum-zirconium-tin master alloys, which are suitable for further alloying into titanium base alloys.
- the present invention also relates to methods for producing aluminum-molybdenum-zirconium-tin master alloys, which are useful in providing titanium base alloys containing refractory materials of greater homogeneity.
- molybdenum-rich zones are segregated regions within a master alloy containing molybdenum concentrations greater than about 80 weight %.
- molybdenum-rich high-density inclusions (HDIs) within titanium alloys are attributable to either cross contamination by pure molybdenum metal, or to unattributed titanium alloy melting practices.
- HDIs high-density inclusions
- Recent investigations have shown that molybdenum-rich areas can form during the single melt thermite master alloy process. Further analysis of the master alloy chemistry and microstructure has led to the hypothesis that the precipitation sequence of the high melting point intermetallic phases plays an important role in the formation mechanism of molybdenum-rich areas.
- the aluminum content should not fall below about 22 weight % at any time during the solidification process. It is believed that both the aluminum: molybdenum and tin: zirconium ratios are important parameters to allow for the lower melting point Al 8 Mo 3 and/or Al 6 (MoTi) phases to be precipitated in preference to the higher melting point Mo and/or Al:Mo 3 (Mo3Al) phases.
- the present invention relates to an aluminum-molybdenum-zirconium-tin master alloy.
- the tin: zirconium ratio is reduced from about 1:2 to about 1:1, thereby lowering the amount of excess zirconium.
- the highest melting point tin: zirconium intermetallic phases have been precipitated, there is little or no excess zirconium to precipitate out with aluminum. Therefore, all of the aluminum is available to combine with molybdenum to precipitate the target lower melting point intermetallic phases.
- This solidification mechanism may be applied to other titanium master alloys which can potentially suffer from the precipitation of high melting point intermetallic phases in other multi-component master alloys. This mechanism may also be applicable to other critical titanium alloys containing alternative elements, such as niobium and tantalum.
- Titanium alloys are commonly produced by melting a blend of pure titanium and a combination of either pure elements and/or master alloys at about 1670° C. Any elements and/or intermetallic phases with a melting point above about 1670° C. may not fully dissolve into the titanium during the repeated melting operations. In addition, elements and/or intermetallic phases with a density above that of titanium will also have a reduced dissolution rate, as they migrate quickly to the solidification zone near the metal-liquid interface. Pure molybdenum and some high molybdenum-containing intermetallic phases, such as Mo 3 Al melt above 1670° C. and have higher densities compared to pure titanium, and are therefore considered to be high-density inclusion (HDI) defects.
- HDI high-density inclusion
- the large (about 300-500 um) molybdenum-rich areas observed in the standard aluminum-molybdenum-zirconium-tin master alloy may not have enough time to dissolve into the titanium during the titanium alloy melting stage. Such areas may also agglomerate into larger molybdenum-rich clusters during the alloy electrode blending and pressing stage prior to melting. By reducing molybdenum-rich areas in the master alloy, the likelihood of producing further molybdenum-based HDI defects in the final alloy is significantly reduced.
- Ti-6Al-2Sn-4Zr-6Mo titanium alloys Ti-6246 alloys. Details related to such alloys are found in U.S. Pat. Nos. 4,104,059 and 4,119,457, herein incorporated by reference.
- both the aluminum: molybdenum and tin: zirconium ratios are key variables in the production of high molybdenum-containing master alloys, and that by careful control of the initial thermite blend chemistry, it is possible to produce a thermite master alloy without the formation of molybdenum-rich areas.
- the 6Al-2Sn-4Zr-6Mo master alloy is produced via the single melt, thermite reaction process.
- the 6Al-2Sn-4Zr-6Mo master alloy has been thoroughly investigated via scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDS). SEM-EDS evaluations were conducted on metallographic mounts of the 6Al-2Sn-4Zr-6Mo master alloy. Numerous molybdenum rich zones were identified in the center and base of the 6Al-2Sn-4Zr-6Mo master alloy. Molybdenum rich zones are segregated regions within a master alloy containing molybdenum concentrations greater than 80 weight %.
- the molybdenum rich zones were quantified by increasing the magnification, such that the only region viewed by the SEM-EDS system was the molybdenum rich zone.
- the typical composition of the molybdenum rich zones characterized in the 6Al-2Sn-4Zr-6Mo master alloy is presented in Table 1, below, prepared by a EVEX SEM-EDS software package.
- the composition found to produce a master alloy free of molybdenum-rich zones while containing the elemental units aluminum, molybdenum, tin, and zirconium is about 36 weight (wt.)% aluminum, about 36 wt. % molybdenum, about 12 wt. % zirconium, about 12 wt.
- a master alloy of this composition is defined as the 6Al-2Zr-2Sn-6Mo master alloy.
- Table 2, below, provides a comparison of the 6Al-2Sn-4Zr-6Mo master alloy composition to the composition of the newly designed single melt, master alloy, 6Al-2Zr-2Sn-6Mo. Two Examples were produced in order to target the composition of the RA 6Al-2Sn-4Zr-6Mo master alloy defined in Table 2.
- Example 1 was produced using a single melt, thermite reaction; further details of this reaction are found in U.S. Pat. No. 5,769,922, herein incorporated by reference.
- the composition of this ingot was determined by analyzing samples extracted from the ingot via atomic emission spectroscopy.
- the elemental composition of Example 1 is found in Table 3, below.
- a metallographic mount of a bottom—center ingot sample was evaluated via SEM-EDS. While examining this sample at 200 times magnification, molybdenum-rich zones were identified.
- the molybdenum rich zones (bright green spots) were quantified by increasing the magnification such that the only region viewed by the SEM-EDS system was the molybdenum rich zone.
- the molybdenum-rich zone composition is presented in Table 4, below, also prepared by the EVEX SEM-EDS software package.
- Example 2 was produced using a single melt, thermite reaction. The composition of this ingot was determined by analyzing strategic samples extracted from the ingot via atomic emission spectroscopy. Elemental composition of Example 2 is presented in Table 5, below.
- the maximum ingot weight should not exceed about 120 pounds, with a weight of about 100 pounds being particularly preferred.
- a single stage thermite reaction in a water-cooled copper retort is used.
- the resulting Ti-6246 alloy is an alpha-beta alloy capable of being heat treated to higher strengths in greater section sizes than a Ti-6Al-4V alloy.
- the properties of this alloy are influenced by its thermo-mechanical history. Enhanced strength, ductility, and low-cycle fatigue properties are contained in the alpha-beta forged material. Beta-forged material contains the best combination of good low-cycle fatigue and fatigue-crack growth resistance.
- the Ti-6246 alloy is similar in forgeability and crack sensitivity to Ti-6-4. This alloy is used in intermediate compressor stages of turbine engines for disks and blades, seals, and for airframe parts.
- the Ti-6246 alloy is produced by melting pure titanium with the 33Al-33Mo-11Sn-22Zr-3Ti (6246 MA) Master Alloy. It is known in the titanium aerospace industry that high density inclusion (HDI) defects such as molybdenum-rich inclusions can significantly decrease the mechanical properties of the Ti-6246 alloy, and several molybdenum-rich HDIs have been reported.
- HDI high density inclusion
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The present invention relates to titanium base alloys, and more particularly to aluminum-molybdenum-zirconium-tin master alloys, which are suitable for further alloying into titanium base alloys. The present invention also relates to methods for producing aluminum-molybdenum-zirconium-tin master alloys, which are useful in providing titanium base alloys containing refractory materials of greater homogeneity. In accordance with the present invention, the tin: zirconium ratio is reduced from about 1:2 to about 1:1, thereby lowering the amount of excess zirconium. After the highest melting point tin: zirconium intermetallic phases have been precipitated, there is little or no excess zirconium to precipitate out with aluminum; therefore, all of the aluminum is available to combine with molybdenum to precipitate the target lower melting point intermetallic phases.
Description
- This application claims priority to U.S. provisional application Ser. No. 61/782,163 which was filed in the United States Patent and Trademark Office on Mar. 14, 2013.
- The present invention relates to titanium base alloys, and more particularly to aluminum-molybdenum-zirconium-tin master alloys, which are suitable for further alloying into titanium base alloys. The present invention also relates to methods for producing aluminum-molybdenum-zirconium-tin master alloys, which are useful in providing titanium base alloys containing refractory materials of greater homogeneity.
- In the production of aluminum-molybdenum-zirconium-tin master alloys, numerous molybdenum-rich zones are typically present. Molybdenum-rich zones are segregated regions within a master alloy containing molybdenum concentrations greater than about 80 weight %. At the present time, molybdenum-rich high-density inclusions (HDIs) within titanium alloys are attributable to either cross contamination by pure molybdenum metal, or to unattributed titanium alloy melting practices. Recent investigations have shown that molybdenum-rich areas can form during the single melt thermite master alloy process. Further analysis of the master alloy chemistry and microstructure has led to the hypothesis that the precipitation sequence of the high melting point intermetallic phases plays an important role in the formation mechanism of molybdenum-rich areas.
- In order to prevent the precipitation of any molybdenum-rich areas, the aluminum content should not fall below about 22 weight % at any time during the solidification process. It is believed that both the aluminum: molybdenum and tin: zirconium ratios are important parameters to allow for the lower melting point Al8Mo3 and/or Al6(MoTi) phases to be precipitated in preference to the higher melting point Mo and/or Al:Mo3(Mo3Al) phases.
- In current aluminum-molybdenum-zirconium-tin master alloys, the aluminum: molybdenum and tin: zirconium ratios are 1:1 and 1:2 respectively. A review of related binary phase diagrams shows that the higher melting point tin: zirconium intermetallic phases will precipitate first during solidification, resulting in an excess of zirconium. The excess zirconium combines with aluminum to precipitate the next highest intermetallic phases, which lowers the aluminum available for precipitation with molybdenum, resulting in the precipitation of high molybdenum content intermetallic phases.
- The present invention relates to an aluminum-molybdenum-zirconium-tin master alloy.
- In accordance with the present invention, the tin: zirconium ratio is reduced from about 1:2 to about 1:1, thereby lowering the amount of excess zirconium. After the highest melting point tin: zirconium intermetallic phases have been precipitated, there is little or no excess zirconium to precipitate out with aluminum. Therefore, all of the aluminum is available to combine with molybdenum to precipitate the target lower melting point intermetallic phases.
- This solidification mechanism may be applied to other titanium master alloys which can potentially suffer from the precipitation of high melting point intermetallic phases in other multi-component master alloys. This mechanism may also be applicable to other critical titanium alloys containing alternative elements, such as niobium and tantalum.
- Titanium alloys are commonly produced by melting a blend of pure titanium and a combination of either pure elements and/or master alloys at about 1670° C. Any elements and/or intermetallic phases with a melting point above about 1670° C. may not fully dissolve into the titanium during the repeated melting operations. In addition, elements and/or intermetallic phases with a density above that of titanium will also have a reduced dissolution rate, as they migrate quickly to the solidification zone near the metal-liquid interface. Pure molybdenum and some high molybdenum-containing intermetallic phases, such as Mo3Al melt above 1670° C. and have higher densities compared to pure titanium, and are therefore considered to be high-density inclusion (HDI) defects. The large (about 300-500 um) molybdenum-rich areas observed in the standard aluminum-molybdenum-zirconium-tin master alloy may not have enough time to dissolve into the titanium during the titanium alloy melting stage. Such areas may also agglomerate into larger molybdenum-rich clusters during the alloy electrode blending and pressing stage prior to melting. By reducing molybdenum-rich areas in the master alloy, the likelihood of producing further molybdenum-based HDI defects in the final alloy is significantly reduced.
- It was previously believed that either cross contamination or an inadequate melting process contributed to the formation of molybdenum-rich HDI defects in the final Ti-6Al-2Sn-4Zr-6Mo titanium alloys (Ti-6246 alloys). Details related to such alloys are found in U.S. Pat. Nos. 4,104,059 and 4,119,457, herein incorporated by reference. In accordance with the present invention, it has been shown that both the aluminum: molybdenum and tin: zirconium ratios are key variables in the production of high molybdenum-containing master alloys, and that by careful control of the initial thermite blend chemistry, it is possible to produce a thermite master alloy without the formation of molybdenum-rich areas.
- The 6Al-2Sn-4Zr-6Mo master alloy is produced via the single melt, thermite reaction process. The 6Al-2Sn-4Zr-6Mo master alloy has been thoroughly investigated via scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDS). SEM-EDS evaluations were conducted on metallographic mounts of the 6Al-2Sn-4Zr-6Mo master alloy. Numerous molybdenum rich zones were identified in the center and base of the 6Al-2Sn-4Zr-6Mo master alloy. Molybdenum rich zones are segregated regions within a master alloy containing molybdenum concentrations greater than 80 weight %.
- The molybdenum rich zones were quantified by increasing the magnification, such that the only region viewed by the SEM-EDS system was the molybdenum rich zone. The typical composition of the molybdenum rich zones characterized in the 6Al-2Sn-4Zr-6Mo master alloy is presented in Table 1, below, prepared by a EVEX SEM-EDS software package.
-
TABLE 1 Typical Molybdenum Rich Zone Composition in the 6Al—2Sn—4Zr—6Mo Master Alloy Elemental composition in the range of: Elements: WT % AT % AlK 7.39 21.73 ZrL 3.15 2.74 MoL 87.62 72.48 TiK 1.84 3.05 - A designed removal of the molybdenum-rich zones was considered by studying and subsequently interpolating relevant phase diagrams with respect to a master alloy containing aluminum, molybdenum, tin, and zirconium. The designed removal was based on selection of a final alloy chemistry that would prevent molybdenum zone enrichment during ingot solidification. In a preferred embodiment, the composition found to produce a master alloy free of molybdenum-rich zones while containing the elemental units aluminum, molybdenum, tin, and zirconium is about 36 weight (wt.)% aluminum, about 36 wt. % molybdenum, about 12 wt. % zirconium, about 12 wt. % tin, and about 4 wt. % titanium. A master alloy of this composition is defined as the 6Al-2Zr-2Sn-6Mo master alloy. Table 2, below, provides a comparison of the 6Al-2Sn-4Zr-6Mo master alloy composition to the composition of the newly designed single melt, master alloy, 6Al-2Zr-2Sn-6Mo. Two Examples were produced in order to target the composition of the RA 6Al-2Sn-4Zr-6Mo master alloy defined in Table 2.
-
TABLE 2 Master Alloy Composition Comparison 6Al—2Zr—2Sn—6Mo Ti—6Al—2Sn—4Zr—6Mo Element Master Alloy Master Alloy Aluminum 36 wt. % 28.5-31 wt. % Molybdenum 36 wt. % 33-35.5 wt. % Tin 12 wt. % 9-11.5 wt. % Titanium 4 wt. % 3-4 wt. % Zirconium 12 wt. % 19.5-22 wt. % - Example 1 was produced using a single melt, thermite reaction; further details of this reaction are found in U.S. Pat. No. 5,769,922, herein incorporated by reference. The composition of this ingot was determined by analyzing samples extracted from the ingot via atomic emission spectroscopy. The elemental composition of Example 1 is found in Table 3, below.
-
TABLE 3 Example 1 Chemistry Aluminum Molybdenum Tin Titanium Zirconium 33.2 wt. % 36.58 wt. % 10.9 wt. % 3.9 wt. % 14.67 wt. % - A metallographic mount of a bottom—center ingot sample was evaluated via SEM-EDS. While examining this sample at 200 times magnification, molybdenum-rich zones were identified.
- The molybdenum rich zones (bright green spots) were quantified by increasing the magnification such that the only region viewed by the SEM-EDS system was the molybdenum rich zone. The molybdenum-rich zone composition is presented in Table 4, below, also prepared by the EVEX SEM-EDS software package.
-
TABLE 4 Typical Molybdenum Rich Zone Compositionin Example 1 Elements: WT % AT % AlK 6.95 20.55 MoL 90.54 75.26 TiK 2.51 4.18 Mo in excess of about 90% - The number and size of the molybdenum rich zones in this sample were significantly reduced when compared to the 6Al-2Sn-4Zr-6Mo master alloy.
- Example 2 was produced using a single melt, thermite reaction. The composition of this ingot was determined by analyzing strategic samples extracted from the ingot via atomic emission spectroscopy. Elemental composition of Example 2 is presented in Table 5, below.
-
TABLE 5 Example 2 Chemistry Aluminum Molybdenum Tin Titanium Zirconium 35.7 wt. % 33.8 wt. % 11.8 wt. % 3.8 wt. % 14 wt. % - A metallographic mount of a bottom—center ingot sample was evaluated via SEM-EDS. After examining this mounted sample at various magnifications, molybdenum rich zones were not identified. Evaluations of the bright green bands displayed indicated that these bands are not molybdenum-rich zones. The typical composition of these bands is presented in Table 6, below, also prepared by the EVEX SEM-EDS software package.
-
TABLE 6 Typical Composition of Bright Green Bands Elements: WT % AT % AlK 31.38 61.37 ZrL 6.64 3.84 MoL 57.43 31.59 SnL 2.78 1.24 TiK 1.77 1.96 - In a preferred embodiment, the maximum ingot weight should not exceed about 120 pounds, with a weight of about 100 pounds being particularly preferred. In a further preferred embodiment, a single stage thermite reaction in a water-cooled copper retort is used.
- Thus, the resulting Ti-6246 alloy is an alpha-beta alloy capable of being heat treated to higher strengths in greater section sizes than a Ti-6Al-4V alloy. The properties of this alloy are influenced by its thermo-mechanical history. Enhanced strength, ductility, and low-cycle fatigue properties are contained in the alpha-beta forged material. Beta-forged material contains the best combination of good low-cycle fatigue and fatigue-crack growth resistance. The Ti-6246 alloy is similar in forgeability and crack sensitivity to Ti-6-4. This alloy is used in intermediate compressor stages of turbine engines for disks and blades, seals, and for airframe parts. The Ti-6246 alloy is produced by melting pure titanium with the 33Al-33Mo-11Sn-22Zr-3Ti (6246 MA) Master Alloy. It is known in the titanium aerospace industry that high density inclusion (HDI) defects such as molybdenum-rich inclusions can significantly decrease the mechanical properties of the Ti-6246 alloy, and several molybdenum-rich HDIs have been reported.
- In accordance with the present invention, it is possible to produce molybdenum rich zones during the production of the 6Al-2Sn-4Zr-6Mo master alloy. It is believed that the sequence of intermetallic phase precipitations enhances the molybdenum concentration during solidification. The novel 6Al-2Zr-2Sn-6Mo master alloy appears to be free from molybdenum rich zones as a result of careful selection of the final alloy chemistry. This careful selection of chemistry appears to prevent the formation of any molybdenum enrichment zones during ingot solidification.
- While the present invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of the invention will be obvious to those skilled in the art. The appended claims and this invention generally should be construed to cover all such obvious forms and modifications, which are within the true spirit and scope of the present invention.
Claims (7)
1. An aluminum-molybdenum-zirconium-tin master alloy composition formed by a single stage thermite reaction, said composition comprising about 36 weight % aluminum, 36 weight % molybdenum, about 12 weight % zirconium, and about 12 weight % tin, wherein the alloy is in a form of an ingot.
2. The composition as recited in claim 1 , wherein the ingot has a weight of about 120 pounds.
3. The composition as recited in claim 2 , wherein the ingot has a weight of about 100 pounds.
4. The composition as recited in claim 1 , wherein the alloy is used for disks, blades and seals of turbine engines.
5. The composition as recited in claim 1 , wherein the alloy is used for airframe parts.
6. The composition as recited in claim 1 , wherein the composition is produced by melting pure titanium with the alloy.
7. The composition as recited in claim 1 , further comprising about 4 weight % titanium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14/772,675 US20160010186A1 (en) | 2013-03-14 | 2014-03-07 | Aluminum-molybdenum-zirconium-tin master alloys |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201361782163P | 2013-03-14 | 2013-03-14 | |
| PCT/US2014/021895 WO2014159085A1 (en) | 2013-03-14 | 2014-03-07 | Aluminum-molybdenum-zirconium-tin master alloys |
| US14/772,675 US20160010186A1 (en) | 2013-03-14 | 2014-03-07 | Aluminum-molybdenum-zirconium-tin master alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US20160010186A1 true US20160010186A1 (en) | 2016-01-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US14/772,675 Abandoned US20160010186A1 (en) | 2013-03-14 | 2014-03-07 | Aluminum-molybdenum-zirconium-tin master alloys |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20160010186A1 (en) |
| WO (1) | WO2014159085A1 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2049291A (en) * | 1934-04-18 | 1936-07-28 | Titanium Alloy Mfg Co | Method of making copper-titanium alloys |
| US3519418A (en) * | 1968-04-22 | 1970-07-07 | Us Air Force | Age-hardenable nickel-base brazing alloy |
| US4104059A (en) * | 1977-05-27 | 1978-08-01 | Reading Alloys, Inc. | Molybdenum-titanium-zirconium-aluminum master alloys |
| DE3409616A1 (en) * | 1984-03-16 | 1985-09-19 | GfE Gesellschaft für Elektrometallurgie mbH, 4000 Düsseldorf | ALLOY FOR THE PRODUCTION OF A TITANIUM ALLOY |
| US7604680B2 (en) * | 2004-03-31 | 2009-10-20 | General Electric Company | Producing nickel-base, cobalt-base, iron-base, iron-nickel-base, or iron-nickel-cobalt-base alloy articles by reduction of nonmetallic precursor compounds and melting |
| WO2009145406A1 (en) * | 2008-05-28 | 2009-12-03 | Korea Institute Of Machinery & Materials | Beta-based titanium alloy with low elastic modulus |
-
2014
- 2014-03-07 US US14/772,675 patent/US20160010186A1/en not_active Abandoned
- 2014-03-07 WO PCT/US2014/021895 patent/WO2014159085A1/en not_active Ceased
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| Publication number | Publication date |
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| WO2014159085A1 (en) | 2014-10-02 |
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