US3625677A - Aluminum alloys - Google Patents

Aluminum alloys Download PDF

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Publication number
US3625677A
US3625677A US786956A US3625677DA US3625677A US 3625677 A US3625677 A US 3625677A US 786956 A US786956 A US 786956A US 3625677D A US3625677D A US 3625677DA US 3625677 A US3625677 A US 3625677A
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cooling
iron
aluminium
rate
alloys
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Howard Jones
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TI Group Services Ltd
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TI Group Services Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12736—Al-base component
    • Y10T428/12764—Next to Al-base component

Definitions

  • the enhanced stability as compared with conventional precipitation-hardened aluminium alloys, was attributed to the low solubility and low diffusion Coefficient of iron and certain other transition metals in aluminium, which inhibits coarsening of precipitated intermetallic particles, and to the characteristically high softening temperatures of aluminium-transition metal compounds in general. It was appreciated that the refinement of the inter-metallic dispersion was dependent upon a high cooling rate and rapid solidication achieved by the air quenching of the atomised particles.
  • the aim of the present invention is to obtain a still further improvement in the properties of such aluminium alloys.
  • the invention we propose to produce an aluminium-rich alloy of enhanced properties of aluminium with iron or another transition element by cooling extremely rapidly from the liquid phase, the cooling being at a rate which is on a different scale from that hitherto applied to such alloys.
  • Our experiments have revealed that, provided the rate of cooling or solidication is kept above a critical value, the resulting structure is of totally different and readily distinguishable form from that obtained from normal rapid cooling.
  • the value of the minimum critical rate of cooling required in order to obtain the novel structure cannot be defined quantitatively, firstly because it is difficult to meas- 3,625,677 Patented Dec. 7, 1971 ice ure the high cooling rates involved with any degree of accuracy and secondly because the critical value will, in any case depend on the nature of the transitional element constitiuent and on the proportion of it present. However, we can say with reasonable confidence that the cooling rate must exceed ⁇ a Value between and 10'7, degrees centigrade per second. The best way of ascertaining whether the desired rate has been attained is by examination and testing of the resulting material.
  • the liner and harder grain structure formed in accordance with the invention is readily distinguishable under the microscope from the normal quenched material.
  • the required extremely rapid rate of cooling from the liquid phase can best be attained by employing the known technique of splat cooling, to be described later.
  • FIG. l is a graph showing the relationship between the hardness and the composition of the different structures obtained by rapid quenching and, for comparison, by chill casting.
  • FIG. 2 is a graph showing how the hardness varies with the annealing temperature for the different zones.
  • the heart of the invention lies in cooling specific materials at such an exceptionally high rate that a new and hitherto unobtained solid structure is obtained having desired properties.
  • the materials are aluminium alloys containing predominantly aluminium with a limited percentage of a transition metal, i.e. a metal forming one of the transition elements in the Periodic Table, this metal further being characterised by having a very low solid :solubility in aluminium.
  • the first choice is iron, which has a maximum solid solubility in aluminium of about 0.05%.
  • Cobalt and nickel may be used, and other possible metals include zirconium, niobium, molybdenum, tantalum and tungsten.
  • the necessary exceptional rate of cooling can be achieved in one of a number of known ways, or by methods not yet known.
  • the chief known method by which the cooling rate can be achieved is that of splat cooling, in which the molten material is thrown in small quantities, of the order of a few milligrams at a time, at high velocity obliquely against a cold surface of good thermal conductivity.
  • splat cooling in which the molten material is thrown in small quantities, of the order of a few milligrams at a time, at high velocity obliquely against a cold surface of good thermal conductivity.
  • a shock-wave produced by gas pressure causing sudden rupturing of a diaphragm or the use of an explosive propels a slug of the molten material almost tangentially against a concave copper strip, so that the material impinging on the strip spreads along it in the form of a foil which is very thin (from less than one to fty microns thick) and is rapidly cooled by conduction to the copper.
  • a cooling rate of up to l()B degrees centigrade per second is attainable.
  • a continuous technique which is more practical for commercial use involves forcing the molten material by gas pressure downwards through a capillary orifice in the base of a stationary reservoir from which it falls into a small Crucible which is rapidly spinning about a vertical axis. It is flung centrifugally from the rim of the crucible onto a surrounding cooled cylindrical copper wall, making impact while still liquid. The resulting akes of rapidly solidified material forming on this wall fall under gravity to be collected at the foot of the wall.
  • Other continuous techniques to achieve the same result would include other methods of spraying liquid alloy on to a stationary or moving substrate. Conventional or plasma jet spraying could be used, in such a way as to ensure that solidication did not occur prior to impact with the substrate, which could be a rotating wheel or drum or a travelling belt and would normally be continuously cooled.
  • Another way of obtaining the desired structure by rapid cooling from the liquid phase is by the use of a laser beam or capacitance discharge from a pointed electrode to produce local melting of a very small region (for example a cubic millimetre) in the surface of a substantial body of the material.
  • the heat is applied for only a brief period, of the order of a millisecond and on removal of the heat input the molten pool of material rapidly cools by conduction into the remainder of the body. Calculations and measurements indicate that a cooling rate higher than l06 degrees centigrade is obtainable in this way, but it is diicult to develop such a method into a continuous commercial process.
  • both with the splat cooling technique and the liquid pool technique microscopic examination of etched sections taken in planes parallel to the direction of heat removal on cooling may reveal that some of the molten material has cooled at a fast enough rate to produce the desired structure and some has not.
  • those parts of the molten body nearest to the cold surface will be more likely to show the desired structure than those which are more remote although the desired structure may occur locally at the exposed surface too.
  • the foil may typically exhibit two main layers although one or other may be absent under particular conditions. These layers are readily distinguishable by etching a polished section with, for example, Kellers reagent, which, while leaving the areas with the desired structure relatively unattacked, darkens the other areas markedly.
  • the structure sought is, of course, a non-equilibrium structure and is distinguished from the structure obtainable by only moderately rapid cooling (also a non-eqilibrium structure) not only by its limited response to etching but also by its enhanced properties, in particular its hardness: there is also a difference in X-ray powder pattern and electron microscopy reveals a much finer scale of structure.
  • moderately rapid cooling also a non-eqilibrium structure
  • the X-ray powder pattern of structure B revealed the presence of a second phase which appears to be FeAls whereas the pattern of structure A showed no such second phase but exhibited asymmetrical broadening or splitting of the reflections from the aluminium lattice which indicated up to a one percent reduction in the lattice parameter.
  • Examination of thinned samples under the electron microscope showed the desired structure A to be basically dendritic with grain colonies having a diameter of the order of a micron and a dendrite arm spacing of around 300 angstrom units.
  • the less hard structure B while having similarly sized grain colonies, had an interphase spacing about ten times as large.
  • the desired structure can be obtained over a range of alloy compositions.
  • the main investigations so far have been done with aluminum containing 8 percent of iron. If the iron content is increased the hardness is increased.
  • FIG. l is a graph showing how the hardness varies with the percentage of iron present in zone A, increasing steeply with increasing iron content. While the high degree of hardness obtained with high iron content represents an improvement in the properties sought the critical minimum cooling rate is increased and so for a given method of cooling and other conditions the yield of the desired structure A will be smaller. Iron contents as high as thirty percent may provide useful materials provided the necessary cooling technique can be improved to produce commercially worthwhile quantities.
  • a reduction in the iron content below 8 percent means that the desired structure can be obtained with lower rates of cooling, or for a given rate of cooling the yield is higher, but at the same time the structure that is produced, even though having the desired characteristics, has them to a less marked degree.
  • FIG. 1 we also show the hardness/iron content relationship for structure B and also at C for the structure obtained by chill casting between copper chills at a cooling rate of about 103 degrees centigrade per second. It is notable that the zone B is harder than this chill-cast structure by a factor of two and the zone A is harder by a factor of four, rellecting the effect of increasing the cooling rate.
  • FIG. 2 is a graph of room temperature hardness for both zones, measured after a one hour anneal at each temperature, plotted against this annealing temperature.
  • the material produced by the method described preferably by the continuous centrifugal splat quenching method, can be' collected and reduced to powder and then used to form useful articles by known powder metallurgy techniques.
  • a possible use for the invention directly without subsequent working may be for forming a hard skin on one or both faces of sheet or strip alloy material by flash-melting of the surface and thus forming a continuous skin or foil of the desired structure by rapid cooling into the remainder of the sheet.
  • novel aluminum alloy structure A cannot be defined precisely in terms of percentages or other qualitative limitations but at the same time it will be possible, by reference to the graphs and the other details given above, to determine whether a given material is or is not of the structure in question.
  • a binary alloy product comprising from 0.05% to 8% by weight of iron, the balance being aluminium together with any impurities and which has been cooled from a liquidus alloy at a rate of at least 105 but not more than 108 degrees centigrade per second, the structure of said product being basically dendritic with grain colonies having a diameter of about a micron and a dendrite arm spacing of about 300 angstrom units.
  • references Cited UNITED STATES PATENTS ture has been obtained by cooling a small volume of 10 RICHARD O. DEAN, Primary Examiner liquidus alloy produced by local melting within a larger body of the alloy.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Continuous Casting (AREA)
US786956A 1967-12-30 1968-12-26 Aluminum alloys Expired - Lifetime US3625677A (en)

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GB59285/67A GB1192030A (en) 1967-12-30 1967-12-30 Aluminium Alloys

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CH (1) CH510126A (de)
DE (1) DE1817499A1 (de)
FR (1) FR1599990A (de)
GB (1) GB1192030A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4347076A (en) * 1980-10-03 1982-08-31 Marko Materials, Inc. Aluminum-transition metal alloys made using rapidly solidified powers and method
US4647321A (en) * 1980-11-24 1987-03-03 United Technologies Corporation Dispersion strengthened aluminum alloys
US4715893A (en) * 1984-04-04 1987-12-29 Allied Corporation Aluminum-iron-vanadium alloys having high strength at elevated temperatures
US4743317A (en) * 1983-10-03 1988-05-10 Allied Corporation Aluminum-transition metal alloys having high strength at elevated temperatures
US4805686A (en) * 1983-10-03 1989-02-21 Allied-Signal Inc. An apparatus for forming aluminum-transition metal alloys having high strength at elevated temperatures
US4889582A (en) * 1986-10-27 1989-12-26 United Technologies Corporation Age hardenable dispersion strengthened high temperature aluminum alloy
CN114318033A (zh) * 2021-12-03 2022-04-12 江西科嵘合金材料有限公司 一种铝铬合金的制备方法

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0025777A1 (de) * 1979-07-16 1981-03-25 Institut Cerac S.A. Verschleissfeste Aluminium-Legierung und Verfahren zu deren Herstellung
DE2946135C2 (de) * 1979-11-15 1982-09-16 Vereinigte Aluminium-Werke Ag, 5300 Bonn Verfahren zur Weiterzerkleinerung von Metallpulver
CA1177286A (en) * 1980-11-24 1984-11-06 United Technologies Corporation Dispersion strengthened aluminum alloys
FR2529909B1 (fr) * 1982-07-06 1986-12-12 Centre Nat Rech Scient Alliages amorphes ou microcristallins a base d'aluminium
EP0105595B1 (de) * 1982-09-03 1988-03-23 Alcan International Limited Aluminiumlegierungen
FR2555610B1 (fr) * 1983-11-29 1987-10-16 Cegedur Alliages a base d'aluminium presentant une grande stabilite a chaud
FR2577941B1 (fr) * 1985-02-27 1991-02-08 Pechiney Alliages amorphes a base d'al contenant essentiellement du ni et/ou du fe et du si et procede d'obtention
DE102007018123B4 (de) * 2007-04-16 2009-03-26 Eads Deutschland Gmbh Verfahren zur Herstellung eines Strukturbauteils aus einer Aluminiumbasislegierung
US20210310102A1 (en) * 2018-07-02 2021-10-07 Sumitomo Electric Industries, Ltd. Aluminum alloy material and method for producing aluminum alloy material

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4347076A (en) * 1980-10-03 1982-08-31 Marko Materials, Inc. Aluminum-transition metal alloys made using rapidly solidified powers and method
US4647321A (en) * 1980-11-24 1987-03-03 United Technologies Corporation Dispersion strengthened aluminum alloys
US4743317A (en) * 1983-10-03 1988-05-10 Allied Corporation Aluminum-transition metal alloys having high strength at elevated temperatures
US4805686A (en) * 1983-10-03 1989-02-21 Allied-Signal Inc. An apparatus for forming aluminum-transition metal alloys having high strength at elevated temperatures
US4715893A (en) * 1984-04-04 1987-12-29 Allied Corporation Aluminum-iron-vanadium alloys having high strength at elevated temperatures
US4889582A (en) * 1986-10-27 1989-12-26 United Technologies Corporation Age hardenable dispersion strengthened high temperature aluminum alloy
CN114318033A (zh) * 2021-12-03 2022-04-12 江西科嵘合金材料有限公司 一种铝铬合金的制备方法
CN114318033B (zh) * 2021-12-03 2022-10-28 江西科嵘合金材料有限公司 一种铝铬合金的制备方法

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Publication number Publication date
GB1192030A (en) 1970-05-13
CH510126A (de) 1971-07-15
FR1599990A (de) 1970-07-20
DE1817499A1 (de) 1969-08-14

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