CN109811205B

CN109811205B - Yb microalloyed Al-Li alloy

Info

Publication number: CN109811205B
Application number: CN201910134164.6A
Authority: CN
Inventors: 高坤元; 田东辉; 丁宇升; 聂祚仁; 黄晖; 文胜平; 吴晓蓝
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2019-02-22
Filing date: 2019-02-22
Publication date: 2021-06-11
Anticipated expiration: 2039-02-22
Also published as: CN109811205A

Abstract

An Yb microalloyed Al-Li alloy belongs to the technical field of alloy materials. The alloy comprises the following components in percentage by mass: 1.11 to 2.00 percent of Li, 0 to 0.19 percent of Yb, less than 0.1 percent of unavoidable impurity content and the balance of Al. The preferred composition ranges for achieving good strengthening effect and economy are Li: 1.35% -1.7%, Yb: 0.15 to 0.19 percent. Through the rapid dispersion and precipitation of the strengthening phase in the Al-Li alloy induced by trace Yb, the alloy with the lower Li content can generate obvious aging strengthening effect, the available Li content component range is expanded, and the good strengthening effect is obtained and the economy is achieved.

Description

Yb microalloyed Al-Li alloy

Technical Field

The invention relates to a Yb microalloyed Al-Li alloy, belonging to the technical field of alloy materials.

Background

The aluminum lithium alloy has the characteristics of low density, high elastic modulus and high specific strength, and is widely applied to the field of aerospace. Its remarkable age strengthening effect results from the massive diffusion precipitation of the metastable Al3Li phase of the L12 structure (Li maximum solid solubility in aluminum is 4.2 wt.%). With increasing Li content, the strength of the alloy increases significantly.

However, as the content of Li increases, a series of difficulties are brought to the production and application of the aluminum-lithium alloy. Firstly, Li is an element with very active chemical properties, oxide inclusions are very easily formed during smelting of the alloy, and when the content of Li in the alloy is increased, the burning loss of the Li element is increased and the oxide inclusions are increased, so that the production cost of the alloy is increased and the comprehensive mechanical properties of the alloy are influenced. Secondly, when the content of Li is high, a large-size AlLi phase is easily formed at a crystal boundary, and a non-precipitation zone (PFZ) of the alloy near the crystal boundary is widened, so that the comprehensive mechanical property of the alloy is influenced. Finally, in recent years, with the rapid development of new energy industries, the price of Li element is rising, so that the production cost of aluminum-lithium alloy is increasing.

When the content of Li is reduced to 1.9 wt% or less, the strengthening effect of the alloy is weak. In the former Soviet Union, trace Sc element is added into the aluminum lithium alloy to improve the performance of the alloy. Researches show that trace Sc elements are added into the Al-Li alloy, and a dispersed L12 core-shell structure strengthening phase is precipitated in the alloy through a complex two-stage aging process, so that the strengthening of the alloy is further improved. And the hardness of the Al-Li-Sc alloy is not obviously increased compared with that of the Al-Li alloy during single-stage aging. And because Sc element is expensive, the industrial application of Sc element is limited.

Yb, which is a microalloying element similar to Sc, is added to the alloy in a small amount and forms a stable Al3Yb phase of L12 structure during aging. And the Yb element is cheap, which is only one-thirtieth of the Sc element and one-third of the Li element. Therefore, the Yb and Li elements are added compositely, and the advantages of the Yb and Li elements are combined to obtain the alloy with lower cost and good aging strengthening effect.

Disclosure of Invention

The invention aims to provide an Yb microalloyed Al-Li alloy which is low in cost and can produce good aging strengthening.

The invention provides a Yb microalloyed Al-Li alloy, wherein Li and Yb in the alloy are Li: 1.10-2.00 percent, Yb 0-0.19 percent but not 0, and the content of inevitable impurities is less than 0.1 percent.

The preferred ranges of the Li and Yb components are Li: 1.35% -1.7%, Yb: 0.15 to 0.19 percent of the alloy can meet the requirement of good aging strengthening effect of the alloy and has economical efficiency.

The technical scheme of the invention has the advantages that:

after the alloy is subjected to solution treatment, the Yb microalloyed Al-Li alloy is subjected to single-stage aging for 1-288h at the corresponding temperature of 80-180 ℃, and has an aging strengthening effect; and compared with Al-Li alloy, the Al-Li-Yb alloy can produce good aging strengthening effect. The technical scheme of the alloy composition of the invention has good aging strengthening effect and economy.

Drawings

FIG. 1 is a curve showing the change of microhardness with aging time of Al-1.12Li and Al-1.11Li-0.17Yb alloys in the aging process at 80 ℃;

FIG. 2 is a curve showing the change of microhardness with aging time of Al-1.35Li and Al-1.35Li-0.17Yb alloys in aging process at 100 ℃;

FIG. 3 is a curve of change of microhardness with aging time of Al-1.70Li and Al-1.67Li-0.17Yb alloys in aging process at 150 ℃;

FIG. 4 is a graph showing the change of microhardness with aging time of Al-2.00Li and Al-2.00Li-0.17Yb alloys during aging at 180 ℃;

FIG. 5 is a graph comparing maximum achievable microhardness with price for alloys of different compositions.

Detailed Description

The invention will be further described with reference to the following drawings and examples, but the invention is not limited to the following examples.

The Yb microalloyed Al-Li alloy comprises the following components in percentage by mass of Li: 1.10 to 2.00 percent, 0 to 0.19 percent of Yb and not 0, the content of inevitable impurities is less than 0.1 percent, and the alloy is subjected to single-stage aging for 1 to 288 hours at the temperature of between 80 and 180 ℃.

Example 1

The components comprising Li and Yb in percentage by mass are respectively Li: 1.1% -1.4%, Yb: 0.15 to 0.17 percent of Al-Li-Yb alloy and Al-Li alloy with the same Li content are taken as examples. As can be seen from FIG. 5, the Al-Li-Yb alloy increased the cost by 3.2% compared to the Al-Li alloy. The component alloy is preferably aged at 100 ℃. From the hardness curve of FIG. 2, it can be seen that Al-Li-Yb is aged for 168h at 100 deg.C

The alloy hardness can reach 74.5Hv, the hardness of the Al-Li alloy has no obvious change and is about 34Hv, and the hardness of the Al-Li-Yb alloy is about 2.2 times that of the Al-Li alloy.

Example 2

The components comprising Li and Yb in percentage by mass are respectively Li: 1.6% -1.7%, Yb: 0.15 to 0.17% of Al-Li-Yb alloy and Al-Li alloy having the same Li content are exemplified. As can be seen from FIG. 5, the Al-Li-Yb alloy has a 0.9% cost increase over the Al-Li alloy, which is preferably aged at 150 ℃. As shown in the hardness curve of FIG. 3, the Al-Li-Yb alloy can reach 92Hv after aging for 24-72 h at 150 ℃, while the hardness of the Al-Li alloy has no obvious change and is about 36Hv, and the hardness of the Al-Li-Yb alloy is about 2.6 times that of the Al-Li alloy.

Comparative example 1

The components comprising Li and Yb in percentage by mass are respectively Li: 1.1% -1.2%, Yb: Al-Li-Yb alloy of 0.15-0.17% and Al-Li with the same Li content are taken as examples of the alloy. The alloy is preferably aged at 80 ℃. As can be seen from FIG. 5, the Al-Li-Yb alloy increased the cost by 1.3% compared to the Al-Li alloy, and from FIG. 1 it can be seen that the hardness of the Al-Li-Yb alloy was only 15Hv higher than that of the Al-Li alloy when aged at 80 ℃ for 48 hours.

Comparative example 2

The components comprising Li and Yb in percentage by mass are respectively Li: 2.0% -2.1%, Yb: Al-Li-Yb alloy of 0.15-0.17% and Al-Li with the same Li content are taken as examples of the alloy. The alloy is preferably aged at 180 ℃. As can be seen from FIG. 5, the cost of Al-Li-Yb alloy is increased by 2.4% compared with Al-Li alloy, and from FIG. 4, the hardness of Al-Li-Yb alloy is only about 5Hv higher than that of Al-Li alloy when aged at 180 ℃ for 48 hours.

By combining the analysis, the Yb microalloyed Al-Li alloy provided by the invention can obtain good aging strengthening effect and has economical efficiency, and the components in percentage by mass are Li: 1.3% -1.7%, Yb: 0.15-0.19%, unavoidable impurity content less than 0.1%, and the balance of Al.

Claims

1. The Yb microalloyed Al-Li alloy is characterized in that Li and Yb in the alloy are Li: 1.35% -1.67%, Yb: 0.15-0.19%, unavoidable impurity content less than 0.1%, and the balance of Al; after the alloy is subjected to solution treatment, single-stage aging is carried out for 1h-288h at the temperature of 80-180 ℃.