Physical metallurgy of aluminum-lithium alloys

Significant advantages in weight reduction and increased strength have place advanced aluminum-lithium alloys at forefront of aerospace materials research. These alloys are being developed to fulfill the ever increasing need for high strength, high properties, light weight and cost effective for aerospace industry. Conventional aluminum alloys has long been in service for aerospace application. The addition of lithium to aluminum improves modulus and decrease density compared to conventional aluminum alloys. Atomic weight of lithium is 7 mass units compared to aluminum 23 mass units, hence there is density reduction of about 3% for each weight percent addition of lithium and about 6% increase in Youngs modulus. In principle weight saving for aerospace structural parts could reach up to 15 %. This paper examines effect of lithium addition on properties, physical metallurgy; various phases developed during processing of these alloys. The addition of Lithium to aluminum form coherent, low density Al3Li (δ׳) precipitates. However the binary alloys have poor mechanical properties which are attributed to strain localization and shearing of soft Al3Li (δ׳) precipitates. This problem has been solved by development of ternary and quaternary alloys containing copper and magnesium. In all aluminum-lithium alloys, small addition of zirconium or scandium is done to improve recrystallization. The new developed aluminum lithium alloys series Al-Li-Cu-X are potential candidate to replace existing conventional alloys in terms of enhanced properties with reduced density.

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Aluminum-lithium alloys: A solution looking for a problem?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121314 ◽

1992 ◽

Vol 50 (1) ◽

pp. 182-183

Author(s):

D.B. Williams

Keyword(s):

Electron Microscopy ◽

Physical Metallurgy ◽

Next Generation ◽

Aerospace Alloys ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

Lithium Alloys

For over a decade, Al-Li base alloys have been described as “the next generation of aerospace alloys”, although to date not much metal is actually flying. The addition of up to 3 wt. % (11 at.%) Li to Al results in decreased density (for obvious reasons) and increased modulus (for unknown reasons). This combination of decreased density and increased stiffness translates into millions of dollars saved in aircraft operation (whether military or civilian) and as a result the aerospace and aluminum industries have invested tens of millions of dollars in an attempt to produce commercial Al-Li based alloys. Electron microscopy and microanalysis have played a major role in the understanding of the physical metallurgy of these alloys, which have yet to see significant service. Their future is uncertain, although there is some limited use for alloys of Al-Li-Cu-Mg-Zr.

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Precipitation in Al-Li-Zr alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121338 ◽

1992 ◽

Vol 50 (1) ◽

pp. 186-187

Author(s):

D.M. Vanderwalker

Keyword(s):

Fracture Toughness ◽

Precipitation Hardening ◽

Weight Ratio ◽

High Strength ◽

Transmission Electron ◽

Water Quench ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

Lithium Alloys ◽

Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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Deformation and fracture behavior of an Al-Li-Cu-Mg-Zr alloy 8090

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178008 ◽

1990 ◽

Vol 48 (4) ◽

pp. 974-975

Author(s):

D.M. Jiang ◽

B.D. Hong

Keyword(s):

High Strength ◽

Deformation And Fracture ◽

Fracture Behaviors ◽

Aluminum Lithium ◽

Carbon Fiber Reinforced Composites ◽

Peak Aged ◽

Aluminum Lithium Alloys ◽

High Strength Aluminum Alloys ◽

Lithium Alloys ◽

Zr Alloy

Aluminum-lithium alloys have been recently got strong interests especially in the aircraft industry. Compared to conventional high strength aluminum alloys of the 2000 or 7000 series it is anticipated that these alloys offer a 10% increase in the stiffness and a 10% decrease in density, thus making them rather competitive to new up-coming non-metallic materials like carbon fiber reinforced composites.The object of the present paper is to evaluate the inluence of various microstructural features on the monotonic and cyclic deformation and fracture behaviors of Al-Li based alloy. The material used was 8090 alloy. After solution treated and waster quenched, the alloy was underaged (190°Clh), peak-aged (190°C24h) and overaged (150°C4h+230°C16h). The alloy in different aging condition was tensile and fatigue tested, the resultant fractures were observed in SEM. The deformation behavior was studied in TEM.

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Lithium depletion during heat treatment of aluminum-lithium alloys

Metallurgical Transactions A ◽

10.1007/bf02643982 ◽

1986 ◽

Vol 17 (4) ◽

pp. 635-643 ◽

Cited By ~ 37

Author(s):

J. M. Papazian ◽

R. L. Schulte ◽

P. N. Adler

Keyword(s):

Heat Treatment ◽

Aluminum Lithium ◽

Lithium Depletion ◽

Aluminum Lithium Alloys ◽

Lithium Alloys

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Microanalysis of precipitates in aluminum-lithium alloys with a scanning ion microprobe

Applied Surface Science ◽

10.1016/0169-4332(89)90975-6 ◽

1989 ◽

Vol 37 (1) ◽

pp. 78-94 ◽

Cited By ~ 14

Author(s):

D.B. Williams ◽

R. Levi-Setti ◽

J.M. Chabala ◽

Y.L. Wang ◽

D.E. Newbury

Keyword(s):

Ion Microprobe ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

Lithium Alloys

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DEVELOPMENT OF A TECHNOLOGICAL PROCESS FOR MANUFACTURING WELDED STRUCTURES

Construction Materials and Products ◽

10.34031/2618-7183-2021-4-5-35-44 ◽

2021 ◽

Vol 4 (5) ◽

pp. 35-44

Author(s):

R. El'cov

Keyword(s):

Phase Composition ◽

Laser Welding ◽

Strain Amplitude ◽

Welded Joints ◽

Structural Phase ◽

Diagnostic Methods ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

First Time ◽

Lithium Alloys

the main goal of this article is to obtain welded permanent joints of modern thermally hardened aluminum and aluminum-lithium alloys made by laser welding, having mechanical characteristics (temporary tensile resistance, yield strength, elongation at break) and structural-phase composition close to or equal to the base alloy. It is shown for the first time that by controlling the parameters of heat treatment of samples with a welded joint of all studied aluminum-lithium alloys, it is possible to purposefully influence the formation of the specified mechanical properties of the weld by changing the structural and phase composition of the weld. The evolution of the struc-tural and phase composition of welded joints of thermally hardened aluminum and aluminum-lithium alloys has been investigated using modern independent diagnostic methods: for the first time, the use of synchrotron radia-tion diffractometry in combination with high-resolution transmission, scanning electron and optical microscopy. The dependences of the increment of deformation under cyclic loading with amplitudes exceeding the elastic limit on temperature are established. For untreated welded joints, it was found that at +85 C, the inhomogeneity of the deformation increment increases, and its speed increases by 8 times for alloy 1461, 5 times for alloy 1420 and 1.5 times for alloy 1441. At a temperature of -60 0C, alloys 1420 and 1461 have hardening stages, during which the value of deformation decreases at given boundary stress values. At +20 0C, there is a uniform increment of defor-mation and an increase in the amplitude of deformation with an increase in the amplitude of stress. At +85 0C, the strain amplitude does not change with increasing stress amplitude, its value is 0.55-0.5 of the strain amplitude at +20 0C. Based on the research results, technological techniques have been developed that allow obtaining me-chanical characteristics and structural-phase compositions of welded joints close to the main alloy during laser welding of aviation thermally hardened aluminum and aluminum-lithium alloys of the Al-Mg-Cu. Al-Mg-Li, Al-Cu-Mg-Li, Al-Cu-Li systems.

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