JPS5836657B2 - Manufacturing method of titanium-manganese alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a T
In the i-Mn alloy, the alloy phase is substantially M g Z
The present invention relates to a method for producing an alloy having an n2 type Laves phase.

Recently, it has become clear that a Ti--Mn alloy having a MgZn-type larvous phase has practical utility as a hydrogen storage material.

Typical examples of these alloy materials are T + Mn1.
5 (binary system), 'rtO, 9 ZrO. I Mnl
,7 yTIO. g IF”eo.I Mn1.2 t
Tio. 9Coo. 1Mn1.3, Tio. 9 Cuo.
1Mn1.3 (ternary system), TI0.8Zr0.2Mn1
．． 2CrO. g l T'i0,8Zr. 2Mn1. g
M.O. 2 (four-element system),'I"tO.t)zro,I
Mn1.4■o. 2 Cro. 4 (quinary system), etc.

The present invention utilizes these Mg Z n 2 type larvous phase Ti
- A practical method for producing Mn-based alloys is provided.

Conventionally, arc melting has been a common method for melting alloys containing Ti as a main component.

The arc melting method has characteristics such as no reaction with the crucible and the ability to easily obtain high temperatures, and is a method often used for melting active metals and high melting point metals.

This arc melting method can generally be divided into a consumable electrode method and a non-consumable electrode method.

The Mg Z n type 2 larvae phase Ti-Mn listed earlier
Conventionally, alloys have been produced by arc melting using non-consumable electrodes.

On the other hand, the method using consumable electrodes is suitable for mass production, but is not suitable for melting the present Ti--Mn alloy because it causes cracks in the electrode.

The non-consumable electrode type arc melting method was an extremely effective method for melting small amounts because there was little concern about contamination with impurities and the alloy had good homogeneity.

However, when we melted a large amount using this method, we found that even if we simply scaled up the method, there were problems such as a decrease in the homogeneity of the alloy and poor mass production, so it was found that it was not an appropriate method. Ta.

Other methods of arc melting, including continuous casting using non-consumable electrodes, were also attempted, but they were found to have many problems with alloy homogeneity, manufacturing cost, and reproducibility.

In addition, as methods other than the arc melting method, there are generally resistance heating melting method and induction heating melting method as practical manufacturing methods, but both of these melting methods are Homogeneity,
These methods were also found to be unsuitable due to problems such as contamination of impurities from crucibles and the like.

Note that Ti2Fe alloys are mass-produced by a general induction heating melting method.

This Ti-Fe alloy has weaker reactivity with a crucible during melting than a Ti-Mn alloy, and the vapor pressure of Fe is M
The vapor pressure of TiMn alloys is closer to that of Ti than that of Ti, so there is less deviation in composition due to evaporation during melting. Due to the presence of the Zn2 type alloy phase, it is necessary to particularly homogenize the alloy phase, but Ti-Fe alloys are metals with a stoichiometric composition of 1:1 atomic ratio. Because it is an intermediate compound, a relatively homogeneous product can be obtained by the induction heating melting method.

The manufacturing method of the present invention solves these problems and provides a practical and novel method for manufacturing the Ti--Mn alloy with excellent cost performance.

The production method of the present invention is based on Ti-M containing Ti and Mn as main components.
Among n-based alloys, this method is characterized by melting by induction heating and then casting in the production of an alloy whose alloy phase is essentially a MgZn2 type larvae phase.

The inventors of the present invention have conducted various studies to solve problems such as ensuring the homogeneity of the alloy and preventing the contamination of impurities, which have been difficult in the past, and have found that it is possible to achieve practical results by strictly controlling the manufacturing conditions. We have discovered a new manufacturing method.

As for the manufacturing conditions, an inert gas is first used as the atmosphere, and then an airtight metal oxide crucible with an apparent porosity of 1 factor or less is used as the crucible for induction heating.

Next, the rate of temperature increase for heating is relatively slow, and the material is melted at a temperature above its melting point.

Also, cooling during casting is performed relatively quickly. Through such induction heating and casting methods, T.
It has been discovered that an i-Mn alloy can be produced.

Furthermore, among these conditions, the optimum values for induction heating melting are: (1) Inert gas atmosphere pressure: 0.1 ~
2 atm, (2) Crucible material: Airtight (apparent porosity 1 or less) magnesia or alumina, (3) Temperature rising speed: 100°C/min or less, (4) Melting temperature: 1400 ~
The conditions of 1600° C. and casting after melting are (5) cooling speed: 200° C./min or more (however, in a temperature range of 500° C. or higher).

The reason for limiting this condition is described below.

(1) Inert gas atmospheric pressure When ordinary vacuum melting is used, Mn in particular evaporates rapidly, causing problems such as compositional deviation. Therefore, it is better to increase the atmospheric pressure in order to suppress the evaporation as much as possible. A reducing gas such as an inert gas or hydrogen is introduced into the vacuum furnace, and the atmospheric pressure is adjusted to at least 0.1 atm.
It is necessary to maintain the temperature above this level in order to reduce the amount of evaporation.

However, if the atmospheric pressure is increased too much, it is not desirable for the safety of the furnace, so the maximum is set at 2 atm, and a range of 0.1 to 2 atm is preferable.

(2) Crucible material When melting a Ti-Mn alloy, the activity of the alloy material is particularly strong. Penetrate outside.

As a result of examining various materials for the crucible material for melting this Ti-Mn alloy, the best results were obtained using an airtight (apparent porosity of 1 or less) magnesia or alumina crucible. This was the case when .

When using these crucibles, it was possible to prevent reaction with the molten metal.

Porous alumina or magnesia crucibles, which are often used for melting general materials (apparent vaporization rate of 10 to 40 φ), cannot be used because of problems such as reactions with the crucible and penetration of molten metal. I could not do it.

However, this Ti-Mn-based crucible is constructed in such a way that only the surface in contact with the molten metal (the inner surface of the crucible) is made of an airtight material with low apparent porosity, and the outside is made of a porous material. It can be used as a melting crucible for alloys.

In addition, as a result of examining crucibles other than the metal oxide type mentioned above, such as carbon crucibles and boron nitride crucibles, we found that they are not preferable because they have problems with the reaction with the crucible and the solubility of the alloy.
Not good.

(3) Temperature rising speed The temperature rising speed to the melting temperature is relatively slow, for example 10
The reason for setting the temperature to be 0° C./min or less is not directly related to the purpose of this topic, but is to prevent the risk of cracking of the crucible.

That is, since an airtight crucible is weak in heat shock, it is desirable to increase the temperature as slowly as possible.

This is also because making the shape of the raw material smaller is more effective in preventing cracks in the crucible due to heat shock.

(4) Melting temperature Mg Z n Type 2 larvae phase Ti-Mn alloys are related to the alloy composition, but the optimum range is 1400'C to 16
A melting temperature of 0.000C was suitable.

In this temperature range, combined with the stirring action of the molten metal, which is a characteristic of induction heating, it was possible to obtain a very homogeneous alloy phase.

If the temperature is too low, the solubility will be poor and the homogeneity of the Tayu alloy will be reduced.If the temperature is much higher than 1,600°C, the solubility will be good, but the evaporation of Mn etc. will increase, In some cases, problems such as concerns about reactions with the crucible may arise.

(5) Cooling speed It has been found that the cooling speed during casting is closely related to the properties of this alloy as a hydrogen storage material (mainly its ability to absorb and release hydrogen).

In other words, the inventors have found that as the cooling speed becomes slower, the above-mentioned properties tend to deteriorate, and conversely, as the cooling speed becomes faster, the above-mentioned properties tend to improve.

Therefore, this cooling speed needs to be fast, and the above characteristics were also good if the cooling speed from casting was, for example, 200° C./min or more in the alloy temperature range of 500° C. or more.

By controlling such manufacturing conditions, the manufacturing method of the present invention becomes a very advantageous method.

Next, examples will be shown.

Is it possible to change the additive elements to the MgZn type 2 larvous phase Ti-Mn alloy, which has Ti-depression as its main component?
Although various combinations are available, this alloy system is primarily used as a hydrogen storage material.

Therefore, in this example, we selected a Ti-Mn binary alloy, which has the simplest alloy composition, from among many products under consideration, and selected a representative combination of T+Mn1.5 and various elements added to it. As a representative of the complex set in the case where T i −Mn
Quintessential alloy, T+0. gzro,I Mn1,4vo
, 2 Cro. 4 shows two examples of manufacturing alloys according to the present invention and their results.

First, Ti. , TiMn1,5 for Mn raw materials and 'r+0, for Ti, Zr, Mn, V, Cr raw materials.
g ZrO. IMn1.4■o. 2 Cro. They were weighed so that there were 4 parts, and the total amount was 1ky.

In this case, the raw material is sponge-like or plate-like, and each side is 1
A material with a purity of 99.5% or more was used with a fine shape of less than 0 resistance.

The weighed raw materials were mixed appropriately and placed in an airtight magnesia crucible (outer diameter 807n7ILφ, inner diameter 68mmφ, height 2ooms), which was a melting crucible, and the outer surface was further protected by a double-walled alumina crucible. It had a crucible structure and was set in a high-frequency induction heating melting furnace.

After vacuum degassing, the inside of the furnace was replaced with high-purity argon gas to bring the pressure to approximately 1 atm.

Then, induction heating of the sample was started. At this time, the temperature was raised to the melting temperature while controlling the heating speed to about 500 C/min.

The melting temperature is TiMnl. 5 is 1450°C1 or 'I
” i0.g zrO.IMn,.4■o.2Cro.
4 was adjusted to 1500°C and dissolved for 20 minutes.

Note that the output frequency used for this melting was 40 KHz.

During the melting process, I was able to observe through the observation window of the furnace body that the sample in the crucible had been successfully melted into a uniform molten metal.

When melting was completed, the heating power was turned off, and the molten alloy was immediately poured into a cast iron mold while maintaining the inert atmosphere.

The melt flow during casting was good and casting was easy.

The cooling speed during casting was approximately 300°C/min in a temperature range of 500°C or higher.

TiMn1.5 and Tt. gZ
As a result of analyzing two types of alloys, r6.1 Mn 1.4 Vo, 2 CrO, 4, by powder X-ray diffraction method, it was confirmed that both were single alloy phases of Mg Z n 2-type Rava phase. .

Figure 1 shows TiMn1.5, Figure 2 shows TlO. G? r. I
Mn1,4vo. 2C rO. The X-ray diffraction pattern of No. 4 is shown.

In the figure, the mark * indicates the diffraction line of the Mg Z n type 2 larvae phase.

It can be seen from the figure that these alloys obtained according to the present invention are single-phase and have very good homogeneity.

These facts were also confirmed by microstructural observation and elemental analysis of the alloy.

Next, the results of examining the properties of the alloy obtained by the production method of the present invention as a hydrogen storage material will be described.

TiMn1.5 obtained by the present invention and T I (1.
g ZrO, I Mn,, 4vo. 2crO. As a conventional example, we selected an alloy with the same strength as the two alloys in No. 4 and obtained by the non-consumable electrode type arc melting method, which has traditionally been considered the best method in terms of homogeneity in the production of Ti-Mn alloys. A table comparing the characteristics of each hydrogen storage material is shown below.

Note that for T+Mn1.5, both were heat-treated at 1100° C. for 20 hours in an argon gas atmosphere.

All measured values are values at 20° C., and the values are shown after repeating hydrogen absorption and release more than 10 times.

In this table, the characteristics as a hydrogen storage material are represented by the amount of absorbed hydrogen and the amount of released hydrogen.

From the table, the properties of the alloy obtained by the method according to the invention are T
iMn and T l O. g Z ro. I M
n 1.4 v, 2CrO. 415, it can be seen that the properties are the same or even slightly improved when compared to alloys obtained by arc melting, which is the best method to date.

In addition, as a result of comparing and considering other properties as a hydrogen storage material, we found that, for example, The properties of the alloy were similar to those of the alloy obtained by conventional arc melting in terms of plateau pressure uniformity, reaction speed with hydrogen, and life test using hydrogen storage and desorption cycles.

In addition to the above examples, M g Z
As a result of examining the n2-type larvae phase Ti-Mn alloy for binary, ternary, quaternary, and quinary systems in the same manner as in the above example, it was possible to obtain a desired alloy with high homogeneity. It was possible to obtain properties of these alloys as hydrogen storage materials that were equivalent to or better than those of alloys obtained by conventional arc melting methods.

As shown in the above embodiments, the present invention utilizes induction heating melting, which is a very practical manufacturing method, to produce a MgZn2 type larvous phase alloy among Ti-Mn alloys containing Ti and pigeon as main components. The disadvantage of the non-consumable electrode arc melting method, which has traditionally been the best method in terms of homogeneity, is that it is not possible to melt in large quantities (conventionally, it is impossible to obtain a homogeneous product). Although it depends on the equipment used, generally the amount dissolved is 0.3 kg.

) and the complicated manufacturing process (the number of melting steps was increased to improve the degree of homogeneity), could be solved all at once by the present invention.

In the production method of the present invention, there is no limit to the dissolution ability, for example,
It is fully possible to melt 1000 kg/time, and the manufacturing equipment,
Mg is very practical in terms of manufacturing conditions, manufacturing costs, etc.
This is a method for producing a Z n 2 type larvae phase Ti-Mn alloy.

In addition, the MgZn type 2 larvae phase Ti-Mn alloy obtained by this manufacturing method is an extremely homogeneous alloy and has excellent properties as a hydrogen storage material, which is the main use of this alloy. be.

[Brief explanation of the drawing]

The drawings show the X-ray diffraction patterns of the alloys obtained by the manufacturing method of the present invention.
5. Figure 2 shows T I. g Z r . I Mn 1
, 4 VO. This is shown for 2Cr6.4.

Claims (1)

[Claims] 1. A method for producing an alloy in which the alloy phase is essentially a MgZn type 2 larvae phase among Ti-Mn alloys mainly containing titanium and manganese, the alloy raw material having an apparent porosity of 1φ or less using a metal oxide crucible of 0.1-2
Temperature increase speed 100℃ under ATM inert gas atmosphere
1. A method for producing a titanium-manganese alloy, which comprises induction heating melting at a melting temperature of 1,400 to 1,600° C. and casting.