JPH0645831B2 - Method for melting Al-Li alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for smelting an Al-Li alloy, which has a particularly high activity and easily reacts with a refractory material, etc. The present invention relates to a method for producing an Al-Li based alloy that has been used.

[Prior Art] Al-Li alloys were produced in the course of research and development of strong Al alloys, and since they are lighter and have higher strength than conventional Al alloys, they are gradually adopted in fields such as aircraft. Is progressing.

There are two methods for producing an Al-Li alloy, that is, an ordinary melting and casting method and a powder metallurgy method.

[Problems to be Solved by the Invention] However, among these conventional manufacturing methods, in the melting and casting method, Li is an active metal, so that it is easy to combine with oxygen, nitrogen, hydrogen, water, and the like, Further, problems such as alloy contamination by a refractory material in contact with hot water, formation of Li ₂ O-based oxide, and reduction of Li content occur. For example, generally, as a high-frequency furnace material for melting, there are refractory materials such as magnesia and graphite, which cause an increase in oxygen and carbon concentrations in the molten metal as described below.

MgO (furnace material) → Mg (gas) + O (in molten metal) C (furnace material) → C (in molten metal) In addition, MgO reacts with Li in the molten metal to give L.
It causes decrease of i content and pollution of molten metal.

2MgO + Li → 2Mg + Li ₂ O In addition, the molten metal is also contaminated in alumina-based and silica-containing zirconia-based refractory materials.

2Al ₂ O ₃ + 3Li → 4Al + 3Li ₂ O ZrO ₂ + Li → Zn + Li ₂ O SiO ₂ + Li → Si + Li ₂ O As described above, a good alloy cannot be obtained by melting using an ordinary refractory container. , When dissolved, oxidative volatilization is likely to be lost.

Oxide is impregnated into the melt, which is extremely difficult to remove.

Since it absorbs gas, there are various difficulties, such as easy occurrence of bubbles in the material.

Therefore, it is necessary to adopt the flux method or the melting and casting method in an inert gas for melting. That is, using an iron crucible, Li
It is necessary to have detailed know-how such as melting in argon and adding separately melted Al to it, and then rapidly stirring and casting.

However, even with such a method, Al and Li cannot be melted in a uniform composition, and since many ingots are contained, the obtained ingot has a drawback that it is extremely fragile during forging.

On the other hand, in the powder metallurgy method, the powder is rapidly cooled and solidified by the atomizing method to be forced to form a solid solution, but the atomizing method cannot avoid the above-mentioned gas absorption and oxide problems, and is obtained. Since powders easily explode, there is also a problem that they are difficult to store.

[Means for Solving Problems] In view of the above-mentioned conventional circumstances, the present invention provides an industrially extremely advantageous melting process of an Al-Li alloy, which comprises melting the Al-Li alloy. In manufacturing, an Al-Li-based alloy melting method is characterized in that melting is performed in a non-oxidizing atmosphere using a container whose inner surface is made of CaO refractory. .

The present invention will be described in detail below.

In addition, in this specification, "%" represents "weight%."

In the present invention, the Al-Li alloy is, for example, 0.5
Al-Li alloy containing ~ 5% Li, and Fe, Mn, Ni, Co, Ti, M as other elements.
1 or 2 of g, Zr, Mo, Cd, and rare earth elements
It may contain more than one species.

The following examples are known as Al-Li alloys.

Al-0.92Li, Al-1.56Li, Al-1.90Li, Al-2.45Li, Al-4.5Li, Al-2.8Li-0.14Zr, Al-2Li-2Mg, Al-1. 85Li-3.4Mg, Al-2Li-2Mg-0.2Zr, Al-1.83Li-3.4Mg-0.19Zr, Al-2.6Li-1.93Mg-0.16Zr, Al-2.6Li- 3.5Mg-0.14Zr, Al-2.7Li-5.2Mg-0.2Zr, Al-1.8Li-4.2Mg-1.06Mn, Al-2.7Li-3.5Mg-0.3Mn, Al-1.95Li-3.96Mg-1.16Fe-
1.05Ni, Al-2.8Li-0.3Mn, Al-3Li-1.3Mn, Al-1.2Li-4.5Cu-0.5Mn-0.2C
d, Al-2.5Li-1.2Cu-0.7Mg-0.12
Zr In the present invention, such an Al—Li alloy is used in a non-oxidizing atmosphere (for example, argon, helium, etc.) in a container having an inner surface made of a CaO-based refractory material in a conventional method such as high frequency or It is melted by heating with a low frequency induction heating method etc.

In the present invention, examples of the CaO-based refractory material forming the inner surface of the container used for melting the Al-Li alloy include refractory materials mainly composed of CaO, such as calcia (CaO) and CaO-enriched dolomide. . As CaO,
Electrofused calcia is extremely suitable because it is dense. Further, calcia (CaO) obtained by firing quicklime, limestone, or slaked lime is also suitable.

The higher the CaO content in such a CaO refractory material,
The generation of impurities is small, and the contamination of the molten metal is more reliably prevented. In the present invention, it is preferable to use a container made of a CaO refractory material having a CaO content of 85% or more, particularly 90% or more, and particularly 95% or more.

[Action] CaO has a high melting point and is extremely stable at high temperatures.
Extremely high stability against molten alloy containing active metals,
It does not react with Li to produce Li oxide. Therefore, Li of the Al-Li alloy melt is not reduced, and the melt is not contaminated with impurities. Further, the refractory material mainly composed of CaO easily reacts with the oxide that causes the non-metallic inclusions, that is, the so-called furnace wall reaction, absorbs the oxide in the molten Al-Li alloy, and greatly reduces the oxide inclusion amount. It is possible to prevent the contamination of oxygen, hydrogen, nitrogen, etc.

Therefore, by using a container whose inner surface is composed of such a furnace material mainly composed of CaO, it is possible to satisfactorily produce an Al-Li-based alloy, which has been conventionally difficult to produce.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Examples 1 to 3 and Comparative Examples 1 to 3 Al-1.56Li alloys each have a CaO content of 85.
% (Example 1), 90% (Example 2), 99% (Example 3) CaO crucible, Fe crucible (Comparative Example 1), Al ₂ O ₃
The crucible (comparative example 2) and the graphite crucible (comparative example 3) were put into an internal heating induction heating melting furnace with an output of 10 kw and a frequency of 50 kHz, and melted under an atmosphere of Ar600 torr to obtain an O concentration in the molten metal. I checked the difference between.

As a result, as shown in Table 1, it was revealed that when a CaO crucible was used, the oxygen content in the molten metal was rapidly reduced, and a good alloy was obtained.

[Effects of the Invention] As described in detail above, the method for melting an Al-Li alloy according to the present invention uses a molten Al-Li alloy in a container whose inner surface is made of a CaO-based refractory material and which is non-oxidizing. Since it is held in an atmosphere, it is possible to obtain an Al-Li-based alloy with extremely high purity, which has heretofore been difficult to melt.

According to such a method of the present invention, the amount of intervening oxides is reduced, and an Al-Li-based alloy with little contamination of oxygen, nitrogen, hydrogen, etc. can be easily obtained.

Therefore, the obtained alloy has extremely excellent properties such as strength.

An alloy of very homogeneous composition is obtained.

Therefore, the ingot after casting does not crack during the forging, and the Al-Li alloy can be melted and cast stably and easily.

Various effects such as are exhibited, and it is extremely advantageous industrially.

Claims (1)

[Claims] 1. When melting an A-Li alloy, the A-Li alloy is melted in a non-oxidizing atmosphere by using a container whose inner surface is made of a CaO refractory material. Method of melting.