Development of aluminum-lithium alloys

[China Aluminum Network] Al-Li alloy is a relatively rapid development of aviation metal materials in the past decade.

Lithium is a lighter element in the world. An aluminum lithium alloy is formed by adding metallic lithium as an alloying element to metallic aluminum. After adding lithium metal, the specific gravity of the alloy can be reduced and the rigidity can be increased while still maintaining high strength, good corrosion resistance and fatigue resistance, and suitable ductility.

In 1983, at the International Aviation Expo in Paris, two of the world’s largest aluminum alloy production companies—Alcon Aluminum Corporation of the United Kingdom and Alcoa Aluminum Corporation of the United States, announced the successful development of a new revolutionary material—Al-Li alloy. .

Experts believe that aluminum-lithium alloy is another milestone in aluminum alloy research and development since the invention of aluminum-zinc alloys in 1943.

In fact, Al-Li alloy is not a fresh concept. The understanding of this material has been going on for quite a long time. Due to the small proportion of lithium, the solubility in aluminum is high, and people have long considered lithium as a close partner of aluminum. As early as the 1920s, scientists and technologists made many comments on aluminum-lithium alloys.

In 1924, Germany developed a kind of industrial aluminum lithium alloy - Si Kelong. This is an aluminum-zinc alloy containing only 0.1% lithium. Its mechanical properties are slightly better than that of the aluminum-magnesium alloy that was prevailing at the time, Duralumin. Due to the fact that Duralumin was accepted at the time, it has influenced the extensive attention that Steellon alloys should receive.

In 1943, the introduction of high-strength aluminum-zinc-magnesium-copper alloys once again underestimated the industrial value of aluminum-lithium alloys. In 1957, the United Kingdom successfully developed X-2020 aluminum alloy containing 1.1% of lithium. This alloy was used on the wings of the U.S. shipborne supersonic attack aircraft and on the skin of the horizontal tailplane. After replacing the aluminum alloy of the original design, the weight of the RA-5C aircraft was reduced by 6%. The former Soviet Union’s scientific and technical workers also developed a lithium-containing 2% aluminum alloy.

After another decade, after the world-wide energy crisis occurred in 1967, countries again began to research aluminum-lithium alloys on a large scale. Due to the development of metallurgical technology and related technologies, the appearance of aluminum-potassium alloys with larger amounts of lithium, smaller specific gravity, and higher strength has become possible. It is believed that many advanced fighter jets and civil aviation aircraft currently use this alloy. Aluminum-lithium alloys cost about one-tenth of that of carbon fiber-reinforced plastics. If aluminum-lithium alloys are used to make Boeing aircraft, the weight can be reduced by 14.6%, fuel savings by 5.4%, aircraft costs by 2.1%, and the annual flying cost of each aircraft will be reduced by 2.2%. It can be expected that with the development of materials science, more and more new alloys will enter the aerospace industry, various industrial sectors and millions of households.