EP0528811A1 - Alliages d'aluminium et de lithium rapidement solidifies et soumis a un double traitement de vieillissement - Google Patents

Alliages d'aluminium et de lithium rapidement solidifies et soumis a un double traitement de vieillissement

Info

Publication number
EP0528811A1
EP0528811A1 EP19910906823 EP91906823A EP0528811A1 EP 0528811 A1 EP0528811 A1 EP 0528811A1 EP 19910906823 EP19910906823 EP 19910906823 EP 91906823 A EP91906823 A EP 91906823A EP 0528811 A1 EP0528811 A1 EP 0528811A1
Authority
EP
European Patent Office
Prior art keywords
component
aluminum
lithium
mpa
ranges
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP19910906823
Other languages
German (de)
English (en)
Inventor
Jerry C. Lasalle
V. R. V. Ramanan
David J. Skinner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honeywell International Inc
Original Assignee
AlliedSignal Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AlliedSignal Inc filed Critical AlliedSignal Inc
Publication of EP0528811A1 publication Critical patent/EP0528811A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • C22F1/047—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 of alloys with magnesium as the next major constituent
    • 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
    • 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
    • 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
    • C22F1/057—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 of alloys with copper as the next major constituent

Definitions

  • Double aged rapidly solidified aluminium-lithium alloys Double aged rapidly solidified aluminium-lithium alloys.
  • the invention relates to rapidly solidified aluminum-lithium-copper-magnesium-zirconium powder metallurgy components having a combination of high ductility and high tensile strength; and more particularly to a process wherein the components are subjected to thermal treatment which improves yield and ultimate strengths thereof with minimal loss in tensile ductility.
  • aluminum-lithium alloys derive strength and toughness through the formation of several precipitate phases, which are described in detail in the Conference Proceedings of Aluminum-Lithium V, edited by T.H. Sanders and E.A. Starke, pub. MCE, (1989).
  • An important strengthening precipitate in . aluminum-lithium alloys is the metastable ⁇ phase which has a well defined solvus line.
  • aluminum-lithium alloys are heat treatable, their strength increasing as ⁇ ' homogeneously nucleates from the supersaturated aluminum matrix.
  • the ⁇ * phase consists of the ordered Ll 2 crystal structure and the composition Al 3 Li.
  • the phase has a very small lattice misfit with the surrounding aluminum matrix and thus a coherent interface with the matrix. Dislocations easily shear the precipitates during deformation, resulting in the buildup of planar slip bands. This, in turn, reduces the toughness of aluminum lithium alloys. In binary aluminum-lithium alloys where this is the only strengthening phase employed, the slip planarity results in reduced toughness.
  • the addition of copper and magnesium to aluminum-lithium alloys has two beneficial effects.
  • the elements reduce the solubility of lithium in aluminum, increasing the amount of strengthening precipitates available.
  • the copper and magnesium allow the formation of additional precipitate phases, most importantly the orthorhombic S' phase (Al 2 MgLi) and the hexagonal T 1 phase (Al 2 CuLi) .
  • these phases are resistant to shearing by dislocations and are effective in minimizing slip planarity.
  • the resulting homogeneity of the deformation results in improved toughness, increasing the applicability of these alloys over binary aluminum-lithium.
  • these phases form sluggishly, precipitating primarily on heterogeneous nucleation sites such as dislocations.
  • the alloys In order to generate these nucleations sites, the alloys must be cold worked prior to aging. Zirconium, at levels under approximately 0.15 wt%, is typically added to the alloys to form the etastable Al 3 Zr phase for grain size control and to retard recrystallization. Metastable Al 3 Zr consists of an Ll 2 crystal structure which is essentially isostructural with ⁇ ' (Al 3 Li) . Additions of zirconium to aluminum beyond 0.15 wt% using conventional casting practice result in the formation of relatively large dispersoids of equilibrium Al 3 Zr having the tetragonal D0 23 structure which are detrimental to toughness.
  • the invention provides a method for increasing the tensile strength of a component composed of a rapidly solidified aluminum-lithium-copper-magnesium-zirconium alloy by subjecting the component to a multi-step aging treatment.
  • the component is a consolidated article, formed from an alloy that is rapidly solidified and consists essentially of the formula Al bal Li a Cu tr Mg c Zr d wherein "a” ranges from about 2.1 to 3.4 wt%, “b” ranges from 0.5 to 2.0 wt%, “c” ranges from 0.2 to 2.0 wt%, and “d” ranges from about 0.4 to 1.8 wt%, the balance being aluminum.
  • the aging treatment to which the component is subjected comprises the steps of subjecting the component to a preliminary aging treatment at a temperature of about 400°C-500°C for a time period ranging from about 0.5 to 10 hours; quenching the component in a fluid bath; and subjecting the component to a final aging treatment at a temperature of about 100°C-250°C for a time period ranging up to about 40 hours.
  • the invention provides a component consolidated from a rapidly solidified aluminum-lithium alloy of the type delineated, which component has been subjected to the multi-step aging treatment specified hereinabove.
  • FIG. 1 is a graph depicting the heat evolution/absorption vs. temperature as measured by differential scanning calorimetry for an Al-2.6Li-l.0Cu-0.5Mg-l.0Zr alloy aged at 590 ⁇ C for 2 hours and ice water quenched;
  • FIG. 2 is a graph of the yield strength vs. aging temperature of a transverse specimen cut from an extruded bar aged for 2 hrs. followed by an ice water quench and subsequent aging for 16 hrs.
  • the open rectangle providing data for a transverse specimen cut from an Al-2.34Li-l.07Zr extruded bar; the specimen being aged at 500°C for 1 hr. was water quenched and subsequently aged at 190°C for 2 hours;
  • FIG. 3 is a graph of the ultimate tensile strength vs. aging temperature for specimens aged in the manner of the specimens of Fig. 2;
  • FIG. 4 is a graph of the tensile elongation vs. aging temperature for specimens aged in the manner of the specimens of Fig. 2;
  • FIG. 5 is a graph depicting the ultimate strength vs. elongation for the alloys of Fi ⁇ . 2 illustrating the improvement in properties extant along the diagonal away from the origin.
  • the invention provides a thermal treatment that increases the tensile strength of a low density rapidly solidified aluminum-base alloy, consisting essentially of the formula wherein "a” ranges from 2.1 to 3.4 wt%, “b” ranges from about 0.5 to 2.0 wt%, “c” ranges from 0.2 to 2.0 wt%, “d M ranges from about 0.4 to 1.8 wt% and the balance is aluminum.
  • the compacted alloy or component is subjected to a preliminary thermal treatment at temperatures ranging from about 400°C to 500 ⁇ C for a period of approximately 0.5 to 10 hours.
  • this treatment dissolves elements such as Cu, Mg, and Li which may be microsegregated in precipitated phases such as ⁇ ' , ⁇ , T, and S.
  • the thermal treatment produces an optimized distribution of cubic Ll 2 particles ranging from about 5 to 50 nanometers in size.
  • the alloy article is then quenched in a fluid bath, preferably held between 0° and 60 ⁇ C.
  • preliminary aging is intended to define the thermal treatment described in the first sentence of this paragraph.
  • the compacted article is then aged at a temperature ranging from about 100°C to 250°C. for a time period ranging up to about 40 hours to provide selected strength/toughness tempers. No cold deformation step is required during this thermal processing, with the result that complex shaped components such as forgings produced from the aged component have excellent mechanical properties.
  • Preliminary aging below approximately 400°C results in a deleterious drop in tensile properties due to the formation of undesirable phases such as the ⁇ (AlLi) phase.
  • Preliminary aging above approximately 500 ⁇ C results in an acceptable combination of tensile properties but does not result in the attainment of the optimum tensile strength since the volume fraction of precipitates is reduced. Grain coarsening may also occur at temperature beyond 550 ⁇ C, further reducing strength.
  • Consolidated articles aged in accordance with the invention exhibit tensile yield strength ranging from about 400 MPa (58 ksi) to 545 MPa (79 ksi) , ultimate tensile strength ranging from about 510 MPa (74ksi) to MPa (83 ksi) and elongation to fracture ranging from about 4 to 9 % when measured at room temperature (20°C) .
  • the tensile properties of consolidated articles formed by extrusion of the alloys listed in Table I and thermally processed in accordance with the method of the invention are listed in Table II.
  • the extruded bars were given a preliminary age for 2 hours at temperatures between 400°C and 600°C and quenched into an ice water bath; subsequently, they were aged at 135°C for 16 hours.
  • Transverse specimens were then cut and machined into round tensile specimens having a gauge diameter of 3/8 - 8 - inches and a gauge length of 3/4 inches.
  • Tensile testing was performed at room temperature at a strain rate of 5.5x10 -4 sec _1
  • Figures 2, 3, and 4 are graphs of the data listed in Table II.
  • the graphs illustrate that the peak ultimate tensile strength (UTS) is a function of both zirconium content and temperature of the first aging treatment.
  • UTS peak ultimate tensile strength
  • a peak UTS of 570 MPa is obtained for 440°C preliminary aged Al-2.6Li-l.Cu-0.5Mg-l.0Zr while a peak UTS of 540 MPa is obtained for a 490°C preliminary aged Al-2.6Li-l.0Mg-0.6Zr.

Landscapes

  • 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)
  • Forging (AREA)
  • Continuous Casting (AREA)
  • Powder Metallurgy (AREA)

Abstract

On soumet un composant, consolidé à base d'un alliage d'aluminium et de lithium rapidement solidifié et contenant du cuivre, du magnésium et du zirconium, a un traitement de vieillissement préliminaire à une température comprise entre environ 400 °C et 500 °C pendant une période d'environ 0,5 à 10 heures, puis on le refroidit par trempe dans un bain de fluide et on le soumet à un traitement de vieillissement final à une température comprise entre environ 100 °C et 250 °C pendant une période allant jusqu'à 40 heures environ. Un tel composant présente une amélioration de sa résistance et de sa capacité d'allongement et est particulièrement utilisable dans des pièces de structure légères pour véhicules tout terrain et pour applications aérospatiales.
EP19910906823 1990-05-02 1991-01-25 Alliages d'aluminium et de lithium rapidement solidifies et soumis a un double traitement de vieillissement Ceased EP0528811A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US51777490A 1990-05-02 1990-05-02
US517774 1990-05-02

Publications (1)

Publication Number Publication Date
EP0528811A1 true EP0528811A1 (fr) 1993-03-03

Family

ID=24061176

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910906823 Ceased EP0528811A1 (fr) 1990-05-02 1991-01-25 Alliages d'aluminium et de lithium rapidement solidifies et soumis a un double traitement de vieillissement

Country Status (5)

Country Link
EP (1) EP0528811A1 (fr)
JP (1) JPH05506271A (fr)
AU (1) AU7582291A (fr)
CA (1) CA2079327A1 (fr)
WO (1) WO1991017281A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5178695A (en) * 1990-05-02 1993-01-12 Allied-Signal Inc. Strength enhancement of rapidly solidified aluminum-lithium through double aging
US5277717A (en) * 1992-02-20 1994-01-11 Alliedsignal Inc. Rapidly solidified aluminum lithium alloys having zirconium for aircraft landing wheel applications
GB9424970D0 (en) * 1994-12-10 1995-02-08 British Aerospace Thermal stabilisation of Al-Li alloy

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4806174A (en) * 1984-03-29 1989-02-21 Aluminum Company Of America Aluminum-lithium alloys and method of making the same
US4747884A (en) * 1985-04-03 1988-05-31 Massachusetts Institute Of Technology High strength aluminum-base alloy containing lithium and zirconium and methods of preparation
US4721537A (en) * 1985-10-15 1988-01-26 Rockwell International Corporation Method of producing a fine grain aluminum alloy using three axes deformation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9117281A1 *

Also Published As

Publication number Publication date
AU7582291A (en) 1991-11-27
WO1991017281A1 (fr) 1991-11-14
CA2079327A1 (fr) 1991-11-03
JPH05506271A (ja) 1993-09-16

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