US3656944A - Method of producing homogeneous ingots of a metallic alloy - Google Patents

Method of producing homogeneous ingots of a metallic alloy Download PDF

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US3656944A
US3656944A US11644A US3656944DA US3656944A US 3656944 A US3656944 A US 3656944A US 11644 A US11644 A US 11644A US 3656944D A US3656944D A US 3656944DA US 3656944 A US3656944 A US 3656944A
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alloy
ampoule
quenching
space
vapor
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US11644A
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Maurice J Brau
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Texas Instruments Inc
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Texas Instruments Inc
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/003—Heating or cooling of the melt or the crystallised material
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
    • C30B29/48—AIIBVI compounds wherein A is Zn, Cd or Hg, and B is S, Se or Te

Definitions

  • ABSTRACT A method for producing homogeneous ingots of an alloy in which one of the components thereof has a high vapor pressure includes the step of sealing the desired'alloy components in a quartz ampoule sufficiently large to include a vapor space therein and heating the ampoule and its contents to at least a temperature at which the components will form a homogeneous liquid mixture.
  • An example of an alloy which can be produced by the instant process is an alloy of cadmium, mercury and tellurium.
  • the method of this invention also includes the steps of quenching the homogeneous alloy from the liquid to the solid state while maintaining a relatively high vapor pressure in the vapor space in the ampoule above the space occupied by the alloy.
  • the high vapor pressure can be maintained in the vapor space by thermally insulating the vapor space during the quenching step.
  • the preferable form of quenching is by immersing only a portion of the space occupied by the alloy in a quenching bath, for example, a quenching oil.
  • a conventional technique for preparing an alloy such as mercury cadmium telluride is to seal the proper portions of the elements in a thick-walled quartz ampoule, which is then evacuated and sealed.
  • the ampoule is placed in a conventional rocking furnace and reacted at approximately 800 C. for twenty-four hours.
  • the ampoule is removed from the rocking furnace, cooled to room temperature and loaded into a conventional vertical Bridgman furnace where it is dropped through a steep temperature gradient (approximately 200 C. per centimeter) at the rate of 2 to 3.2 millimeters per hour.
  • the resulting ingot of mercury cadmium telluride may contain one or several single crystal regions.
  • a concentration gradient will be established from one end of the ingot to the other due to segregation of the component atoms during the slow freezing process.
  • the gas stream cools the liquid alloy to a solid state at a relatively rapid rate.
  • the final ingot contains some blow holes or cavities and is piped" or contains piping throughout a portion of the ingot. This process represents an improvement over the previous processes, but still results in a usable yield of around 50 percent of the originally formulated composition.
  • alloy ingots specifically ingots composed of mercury, cadmium and tellurium
  • molten alloys can be quickly solidified without producing blow holes piping throughout portions of the ingot.
  • This invention therefore, provides a method of producing an alloy in which one of the components has a relatively high vapor pressure by sealing the desired alloy components in an ampoule sufficiently large to include a vapor space therein and heating the ampoule and contents to at least the temperature at which the components will form a homogeneous liquid mixture, the improvement in this method comprising quenching the homogeneous alloy from the liquid to the solid state while maintaining a high vapor pressure in the vapor space above the space occupied by the alloy.
  • a mercury cadmium telluride alloy by sealing the desired proportions of mercury, cadmium and tellurium in an ampoule sufficiently large to include a vapor space and heating the ampoule and contents in a furnace to at least a temperature at which the components will form a homogeneous liquid mixture
  • the improvement comprising therrnally insulting the portion of the ampoule containing the vapor space, removing the ampoule from the furnace, and quenching the alloy from the liquid to the solid state by cooling at least a portion of the space occupied by the alloy. Quenching is preferably accomplished by immersion in an oil quenching bath.
  • FIG. 1 is a schematic cross sectional view of a rocking furnace
  • FIG. 2 is a schematic view of an ampoule and contents being cooled in a quenching bath
  • FIG. 3 is a schematic cross sectional view of an alternate embodiment to that shown in FIG. 2.
  • Mercury cadmium telluride is a ternary composition which is often described as a pseudo-binary since the mercury and cadmium behave as though they were only one element in combination with tellurium.
  • This composition is highly useful for the manufacture of electromagnetic radiation detectors. By varying the composition of the material, the detectable wavelength of the devices fabricated therefrom can be varied over a considerable range. It is desirable to pick a given wavelength to be detected and tailor the mercury cadmium telluride alloy such that it is capable of detecting the desired wavelength. Thus, the exact composition of the material becomes very important.
  • a conventional electrically powered resistance-heated rocking furnace 10 is composed of an alumina wall 12 which defines a cylindrical chamber 14. Positioned within the chamber 14 is a quartz ampoule 16 containing a mixture 18 of the desired proportions of mercury, cadmium and tellurium. The mixture is shown in a liquid state. The portion of the ampoule which is not occupied by liquid, i.e., the vapor space 20, is surrounded by a thermal insulator 22.
  • the insulator can be composed of microquartz or can be composed of a fire brick plug as shown.
  • a heat sink, such as stainless steel, could also be employed to maintain a suitable temperature in the void space.
  • the insulator 22 has a cavity 24 into which the portion of the ampoule containing the vapor space is inserted.
  • the top end of the furnace 10 has a plug 28 of quartz wool tightly packed therein to retain heat within the chamber 14.
  • the lower end of the furnace has a plug 30 of quartz wool packed therein surrounding a stainless steel conduit 32, one end of which opens toward the bottom of ampoule 16.
  • the ampoule 16 is inserted into the cavity 24 of fire brick insulator 22.
  • the ampoule and insulator are inserted into the cavity 14 of the furnace 10.
  • the end plugs 28 and 30 are then inserted and the steel conduit 32, which is at the same time positioned to direct a flow of gas toward the bottom of the ampoule 16.
  • power to the heating element is cut off and a stream of cool gas, for example, nitrogen, is caused to flow from end 34 of conduit 32 and impinge upon the bottom of the ampoule 16.
  • the molten alloy 18 is cooled from the liquid state to the solid state while retaining sufficient heat in vapor space to maintain therein a relatively high vapor pressure of at least one of the components of the molten alloy.
  • the vapor pressure of mercury is the significant factor.
  • the ampoule 40 is partially filled with alloy 42 and has a vapor space 44 surrounded and thermally insulated by a fire brick or other suitable insulator 46.
  • the ampoule and contents are heated in a rocking furnace by a procedure similar to that described in conjunction with FIG. 1. However, no tube for cooling gas is necessary.
  • an eyelet 48 has connected thereto a wire 50 extending through a channel 52 in the insulator 46.
  • the ampoule 40 and insulator 46 are together removed from the rocking furnace and immediately thereafter quenched.
  • at least a portion of the ampoule 40 containing the alloy 42 is immersed in a quenching bath 54 in a suitable container 56.
  • the quenching bath 54 can be any suitable quenching liquid; it is preferably a conventional metallurgical quenching oil.
  • the function of the insulator in both embodiments, FIG. 1 and FIG. 2 is to retain heat in the vapor space 20 (FIG. 1) and 44 (FIG. 2) to prevent rapid cooling of the vapor therein.
  • the vapor pressure of mercury is maintained at a relatively high level while cooling the molten alloy.
  • maintaining the vapor pressure in the vapor space 44 prevents flashing of mercury from within the molten alloy body while the latter is cooling. This, of course, prevents the production of blow holes and prevents piping or pitting in the solidified alloy ingot.
  • an auxiliary electric resistance heater 58 insulated by a layer 50 of quartz wool can be positioned about the vapor space to maintain a higher temperature and thus a higher vapor pressure in the vapor space.
  • EXAMPLE I An approximately 6-inch long quartz ampoule having an ID of about 8 millimeters and an OD of about 12 millimeters is first washed and then etched in a conventional manner by rinsing the ampoule with an etch solution. After being so treated, the ampoule is rinsed with deionized water followed by distilled water. The ampoule is then vacuum fired and placed in a glove box containing a nitrogen atmosphere. In the glove box, the ampoule is loaded with 7.7259 grams of mercury, 1.1433 grams of cadmium, and 6.1808 grams of tellurium.
  • the ampoule After loading, the ampoule is evacuated to a residual pressure of 3 times 10' Torr, sealed with a hydrogen and oxygen torch, inserted into a fire brick insulator similar to that shown in FIG. 1, and wrapped with a layer of quartz wool.
  • the ampoule is then positioned in a conventional rocking furnace.
  • the bottom end of the furnace is provided with a quartz wool pack around which a stainless steel tube having an ID of approximately 5 millimeters.
  • the tip of the tube is positioned approximately one-half inch from the bottom of the ampoule.
  • the rocking furnace is raised to a temperature of about 810 C. and rocked for a 24 hour period while the temperature is maintained at that level.
  • the furnace is stopped and the plug at the upper end of the furnace removed.
  • the current used to heat the furnace is cut off and nitrogen is introduced through the stainless steel tube under a pressure of about 6.2 psig.
  • the nitrogen circulates around the sides of the ampoule and through the quartz wall layer surrounding the ampoule (layer 26, FIG. 1). The nitrogen exits through the upper end of the furnace.
  • the mercury cadmium telluride is quenched from the liquid to the solid state in approximately 25 seconds.
  • the ampoule is removed from the furnace and the ingot removed from the ampoule. Thereafter the ingot is annealed by conventional methods. The ingot over its length of approximately 4 inches is sliced into 20 substantially equal slices along planes perpendicular to the axis of the ingot. After analysis of the individual slices the ingot is found to be substantially homogeneous. About 75% of the ingot is found to be usable.
  • Example 2 The procedure of Example 1 is repeated except that no thermal insulator is utilized for the vapor space. After quenching with a nitrogen stream the solidified alloy is removed from the ampoule, annealed and sliced into 20 substantially equal slices along its length. Upon examination of the slices, evidence of pitting and blow holes are observed on the slices which were originally near the vapor space in the ampoule. The occurrence of the blow holes and pitting, of course, cuts down the usable yield of alloy from the ingot. The usable portion of the ingot is less than that obtained with the ingot of Example 1.
  • Example 3 The heating procedure of Example I is followed except that l0.2608 grams of mercury, 1.4736 grams of cadmium and 8.2656 grams of tellurium are utilized as starting materials.
  • the cooling gas tube is removed from the furnace and replaced by a quartz wool plug.
  • the insulator and the ampoule containing molten alloy are removed from the furnace by grasping a wire handle similar to that illustrated in FIG. 2.
  • the tip of the ampoule containing the molten alloy is immersed to a depth of about 1 centimeter in a quenching oil.
  • the time required for solidification of the alloy is less than 20 seconds.
  • the ingot is removed from the ampoule, annealed and sliced into two portions along its axis. No evidence of piping or blow holes is discovered.
  • the ingot is substantially homogeneous throughout its entire length. Substantially the entire ingot is usable for the production of electromagnetic radiation detectors.
  • quenching the alloy from the liquid to the solid state by selectively cooling that portion of the ampoule containing the alloy, while maintaining the temperature of the remaining portion of the ampoule sufficiently high to prevent flashing of said high-vapor-pressure component from within the molten alloy during said quenching.
  • said alloy comprises at least one Group II element and at least one Group Vl element.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
US11644A 1970-02-16 1970-02-16 Method of producing homogeneous ingots of a metallic alloy Expired - Lifetime US3656944A (en)

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DE (1) DE2106412A1 (enrdf_load_stackoverflow)
FR (1) FR2078647A5 (enrdf_load_stackoverflow)
GB (1) GB1316406A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849205A (en) * 1973-08-27 1974-11-19 Texas Instruments Inc Enhancement of solid state recrystallization by induced nucleation
US4011074A (en) * 1974-03-25 1977-03-08 Consortium Fur Elektrochemische Industrie Gmbh Process for preparing a homogeneous alloy
FR2464225A1 (fr) * 1979-08-30 1981-03-06 Hughes Aircraft Co Procede de production de tellurure de mercure et de cadmium monocristallin et ce produit
US4578145A (en) * 1979-07-05 1986-03-25 U.S. Philips Corporation Method of making monocrystalline ternary semiconductor compounds
US4582683A (en) * 1984-12-03 1986-04-15 Texas Instruments Incorporated (Hg,Cd,Zn)Te crystal compositions
US4654196A (en) * 1983-08-17 1987-03-31 Commissariat A L'energie Atomique Process for producing a polycrystalline alloy
US9790580B1 (en) * 2013-11-18 2017-10-17 Materion Corporation Methods for making bulk metallic glasses containing metalloids

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1197755A (en) * 1980-05-22 1985-12-10 Robert A. Lancaster Controlled directional solidification of semiconductor alloys

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2953690A (en) * 1957-09-03 1960-09-20 Nat Res Dev Photosensitive cells, radiation filters and semiconductor materials for use in such cells and filters
US3318669A (en) * 1960-06-03 1967-05-09 Siemens Schuckerwerke Ag Method of producing and re-melting compounds and alloys
US3335084A (en) * 1964-03-16 1967-08-08 Gen Electric Method for producing homogeneous crystals of mixed semiconductive materials
US3468363A (en) * 1967-10-10 1969-09-23 Texas Instruments Inc Method of producing homogeneous ingots of mercury cadmium telluride

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2953690A (en) * 1957-09-03 1960-09-20 Nat Res Dev Photosensitive cells, radiation filters and semiconductor materials for use in such cells and filters
US3318669A (en) * 1960-06-03 1967-05-09 Siemens Schuckerwerke Ag Method of producing and re-melting compounds and alloys
US3335084A (en) * 1964-03-16 1967-08-08 Gen Electric Method for producing homogeneous crystals of mixed semiconductive materials
US3468363A (en) * 1967-10-10 1969-09-23 Texas Instruments Inc Method of producing homogeneous ingots of mercury cadmium telluride

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849205A (en) * 1973-08-27 1974-11-19 Texas Instruments Inc Enhancement of solid state recrystallization by induced nucleation
US4011074A (en) * 1974-03-25 1977-03-08 Consortium Fur Elektrochemische Industrie Gmbh Process for preparing a homogeneous alloy
US4578145A (en) * 1979-07-05 1986-03-25 U.S. Philips Corporation Method of making monocrystalline ternary semiconductor compounds
FR2464225A1 (fr) * 1979-08-30 1981-03-06 Hughes Aircraft Co Procede de production de tellurure de mercure et de cadmium monocristallin et ce produit
US4654196A (en) * 1983-08-17 1987-03-31 Commissariat A L'energie Atomique Process for producing a polycrystalline alloy
US4582683A (en) * 1984-12-03 1986-04-15 Texas Instruments Incorporated (Hg,Cd,Zn)Te crystal compositions
US9790580B1 (en) * 2013-11-18 2017-10-17 Materion Corporation Methods for making bulk metallic glasses containing metalloids

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DE2106412A1 (de) 1971-09-02
GB1316406A (en) 1973-05-09
FR2078647A5 (enrdf_load_stackoverflow) 1971-11-05

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