Lithium-aluminum alloy
[CAS# 87871-87-2]

Identification

• Classification: Inorganic chemical industry >> Simple substance
• Name: Lithium-aluminum alloy
• Molecular Formula: Al.Li
• Molecular Weight: 33.92
• CAS Registry Number: 87871-87-2
• EC Number: 632-971-7
• SMILES: [Li].[Al]

Properties

• Density: 1.56 g/mL (25 °C) (Expl.)
• Melting point: 718 °C (Expl.)

Safety Data

• Hazard Symbols: GHS02;GHS05 Danger
• Risk Statements: H260-H314
• Safety Statements: P223-P231+P232-P260-P280-P303+P361+P353-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Substances or mixtures which in contact with water emit flammable gases	Water-react.	1	H260

• Transport Information: UN 3131

Discovery and Applications

Lithium-aluminum alloy is a metallic material composed primarily of lithium and aluminum, typically with lithium content ranging from a few percent up to around 10-12% by weight. These alloys combine the low density of lithium with the strength and corrosion resistance of aluminum, resulting in lightweight materials with enhanced mechanical properties. The development of lithium-aluminum alloys dates back to the mid-20th century when interest in lightweight structural materials grew, particularly for aerospace and transportation applications.

The addition of lithium to aluminum reduces the alloy’s density significantly, making it one of the lightest structural metals available. This density reduction is accompanied by an increase in stiffness, as lithium additions improve the modulus of elasticity. The combination of low weight and increased stiffness makes lithium-aluminum alloys attractive for applications requiring weight savings without compromising strength.

Lithium-aluminum alloys have been widely studied and utilized in the aerospace industry, where weight reduction is critical for fuel efficiency and performance. Components such as aircraft structural parts, fuselage panels, and satellite frames have benefited from these alloys’ properties. The alloys provide a favorable strength-to-weight ratio, improved fatigue resistance, and good weldability compared to conventional aluminum alloys.

In addition to aerospace, lithium-aluminum alloys have potential uses in automotive and sports equipment manufacturing, where lightweight materials contribute to improved efficiency and handling. The alloys’ combination of low density and mechanical strength supports the design of lighter vehicles and performance gear.

The microstructure of lithium-aluminum alloys is characterized by the formation of intermetallic phases, primarily Al₃Li, which contribute to strengthening through precipitation hardening. The size, distribution, and morphology of these precipitates influence the mechanical behavior of the alloy. Heat treatment processes are used to optimize these microstructural features and enhance properties such as tensile strength and toughness.

Corrosion resistance is an important consideration in lithium-aluminum alloys. While lithium additions can increase susceptibility to corrosion under certain conditions, alloy design and surface treatments are employed to mitigate these effects. Protective coatings and anodizing are commonly used to improve durability in harsh environments.

Lithium-aluminum alloys also exhibit good electrical and thermal conductivity, which can be advantageous in applications requiring heat dissipation or electrical performance. Their relatively low melting points compared to pure aluminum allow for ease of casting and fabrication.

Safety and handling of lithium-aluminum alloys require attention due to lithium’s high reactivity, especially in powder or fine particulate form. However, in alloyed and bulk forms, lithium is stabilized within the aluminum matrix, reducing reactivity risks. Manufacturing and recycling processes are designed to manage these safety aspects effectively.

Overall, lithium-aluminum alloys represent an important class of lightweight structural materials with a balance of low density, improved stiffness, and mechanical strength. Their discovery and development have significantly contributed to advancements in aerospace engineering and continue to influence materials science in sectors seeking weight reduction and enhanced performance.

References

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