JPH05320785A - Method for degassing from al alloy powder - Google Patents

Abstract

PURPOSE:To provide the method for degassing from Al allay powder in which the removal of a hydrogen gas and the suppression of the destruction of the fine structure caused by rapid solidification are enabled. CONSTITUTION:As for the method for degassing from Al alloy powder, Al allay powder having an amorphous phase whose crystallization temp. is defined as Tx is subjected to primary degassing treatment under the condition in which the temp. T1 satisfies Tx-100K<=T1<=Tx+150K to change the amorphous phase into a crystalline phase. Next, this Al alloy powder is subjected to secondary degassing treatment under the condition in which the temp. T2 satisfies Ti+50K<=T2<=T1+150K. A stable crystalline structure can be obtd. by the primary degassing treatment, and degassing can efficiently be executed by the secondary degassing treatment. At this time, because the crystalline structure of the Al allay powder is stable, the diffusion of atoms at a high temp. can be suppressed to prevent the coarsening of the structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for degassing Al alloy powder, particularly Al alloy powder having an amorphous phase.

[0002]

2. Description of the Related Art An Al alloy powder having an amorphous phase contains hydrogen gas due to its manufacturing method. This hydrogen gas should be removed because it remains in the molded body and causes a decrease in strength when the molded body is manufactured by performing compression molding, hot extrusion processing or the like from the Al alloy powder. ..

Conventionally, in order to efficiently perform the degassing treatment of Al alloy powder, the temperature during the degassing treatment is set to the crystallization temperature of the amorphous phase Tx + 150K to Tx + 300K (however, T
(It depends on x).

[0004]

However, if the temperature of the degassing process is too high, the amount of residual hydrogen in the Al alloy powder decreases, but on the other hand, the fine structure is destroyed by the rapid solidification, so that the structure is effectively removed. It becomes impossible to obtain a high-strength molded product that is used.

In view of the above, it is an object of the present invention to provide the degassing method capable of removing hydrogen gas and suppressing the destruction of the fine structure by rapid solidification by dividing the degassing process into two stages. ..

[0006]

Degassing method of the Al alloy powder according to the present invention SUMMARY OF THE INVENTION may, in Al alloy powder having an amorphous phase crystallization temperature is Tx, the temperature T ₁ is Tx-100K ≦ T ₁
≦ Tx + 150K said subjected to primary degassing treatment under conditions of an amorphous phase is a phase change in the crystalline phase, and then the Al alloy powder, temperature T ₂ is _{T 1 + 50K ≦ T 2 ≦} T 1 +15
It is characterized in that the secondary degassing treatment is performed under the condition of 0K.

[0007]

In the primary degassing process, if the temperature T ₁ is set relatively low as described above, degassing is performed slowly, but a fine and stable crystal structure can be obtained from the fine structure produced by rapid solidification. ..

Since the temperature T ₂ is set relatively high in the secondary degassing process, degassing can be performed efficiently. In this case, since the crystal structure of the Al alloy powder is stable, the diffusion of atoms at a high temperature is suppressed and the coarsening of the structure is prevented.

In the primary degassing process, when the temperature T ₁ is T ₁ <Tx-100, the crystallization of the Al alloy powder is not completed within a practical range, while when T ₁ > Tx + 150K, a rapid phase change occurs. Along with that, the fine structure is destroyed by the rapid solidification. In the secondary degassing process, the temperature T ₂ is T ₂
When <T ₁ + 50K, non-uniformity of the structure occurs in the primary degassing process, it cannot be removed during the secondary degassing process, while when T ₂ > T ₁ + 150K, the primary degassing process occurs. Stabilization of the structure due to the treatment is not effectively utilized in the secondary degassing treatment, resulting in lower strength of the molded body.

[0010]

EXAMPLES Example 1 A molten metal having a composition of Al ₉₀ Fe ₇ Y ₃ (numerical value is atomic%) was prepared, and then, using an ultrasonic gas atomizer, under a He gas pressure of 100 kgf / cm ² . An Al alloy powder was produced. Then, the Al alloy powder was subjected to classification treatment to adjust its particle size to 22 μm or less.

The Al alloy powder was subjected to X-ray diffraction and differential calorimetric analysis (DSC), and the structure thereof was examined. As a result, it was found that the structure was a mixed phase structure composed of a crystalline phase and an amorphous phase, and that of the amorphous phase. The crystallization temperature Tx was found to be 653K.

Next, using the Al alloy powder, various compacts were manufactured through the following steps. That is, a step of producing a green compact by subjecting the Al alloy powder to cold isostatic pressing (CIP) under the condition of 4000 kgf / cm ² , a step of degassing the green compact, and an extrusion temperature of the green compact. This is a step of performing hot extrusion under the condition of 673K.

The degassing process was carried out in a vacuum of 10 ^-3 Torr or less in two steps, a primary degassing process and a secondary degassing process.

Table 1 shows the degassing conditions and the characteristics of various molded products.

[0015]

[Table 1]In Table 1, the molded bodies (3) to (5) are the primary degassing treatments.
Reason temperature T₁Is Tx-100K ≦ T₁≤Tx + 150K
And the temperature T of the secondary degassing process ₂Is T₁
-50K≤T₂≤T₁Meets the condition of + 150K
So it has high strength.

Since the temperature T ₁ of the degassing process is too high, the molded body (1) becomes low in strength because the fine structure due to rapid solidification is destroyed. The molded body (2) has a temperature T _{1 of the} primary degassing process.
If the difference between the temperature T ₂ of the second degassing process has a low strength because it is too small. Since the difference between the temperature T ₁ of the primary degassing treatment and the temperature T ₂ of the secondary degassing treatment is too large in the formed bodies (6) and (7), the stabilization of the structure by the primary degassing treatment is 2 It is not effectively used in the subsequent degassing process and has low strength. The molded bodies (8) and (9) are the temperature T of the primary degassing process.
_{Since 1} is relatively low and the time is short, the crystallization of the amorphous phase is not completed, and as a result, a rapid phase change occurs in the secondary degassing process, resulting in low strength.

Table 2 shows another molded article (1
The degassing conditions and characteristics for a) to (10a) are shown. The composition of each of the molded bodies (1a) to (10a) and the manufacturing method thereof are the same as those in Table 1.

[0018]

[Table 2] In Table 2, the molded body (4a) ~ (6a), the temperature T ₁ of the primary degassing process _{Tx-100K ≦ T 1 ≦ Tx} + 15
Satisfies the condition of 0K, also the temperature T ₂ of the second degassing process satisfies the condition of _{T 1 -50K ≦ T 2 ≦ T} 1 + 150K, a high strength.

The molded body (3a) is a fine structure by rapid solidification because the temperature T ₁ of the primary degassing process is too high to come into low-strength destroyed. The formed bodies (9a) and (10a) did not complete the crystallization of the amorphous phase because the temperature T ₁ of the primary degassing process was too low, and as a result, a rapid phase change occurred in the secondary degassing process. Results in low strength.

Next, using the above Al alloy powder, the degassing time was changed and the temperatures T ₁ and 2 of the primary degassing were changed.
Various molded products were manufactured by setting the difference from the temperature T _{2 in the} subsequent degassing treatment to 50 K and 150 K, respectively, and setting other conditions to the same as above.

Table 3 shows the degassing treatment conditions and the characteristics of various molded products when the temperature difference was set to 50K, and Table 4 shows the degassing treatment conditions and various molded products when the temperature difference was set to 150K. Shows the characteristics of.

[0022]

[Table 3]

[0023]

[Table 4] In Tables 3 and 4, the molded bodies (12) to (18) and (22) to (28) have high strength. From this, 1
It can be seen that the time of the subsequent degassing treatment should be set to exceed 0.2 hours.

When the time of the primary degassing treatment is 0.2 hours or less, the structure of the Al alloy powder is not stabilized, and the remaining solid solution atoms diffuse in the secondary degassing treatment.
The strength becomes low as in 0), (11) and (20), (21).

On the other hand, when the time of the secondary degassing treatment exceeds 4 hours, the diffusion of atoms, which has been suppressed until then, occurs, so that the strength becomes low like the molded bodies (19) and (29).

FIG. 1 shows the relationship between the time and strength of the secondary degassing process. The line a indicates that the temperature T ₁ of the primary degassing process is 723K.
In the case of, the line b shows that the temperature T ₁ of the primary degassing treatment is 62.
It corresponds to the case of 3K respectively. Each code (15) to (1
9) and (25) to (29) are molded bodies (15) to (1).
9) and (25) to (29), respectively.

As is clear from Tables 3 and 4, and FIG.
The time of the secondary degassing treatment is preferably set to 4 hours or less. The lower limit of the time is 0.5 from the degassing effect.
Set in time.

The present invention is not applicable as a method for degassing an Al alloy powder which shows a heat generation of 10 J / g or more in differential calorimetric analysis after the primary degassing treatment.

Example 2 A molten metal having a composition of Al ₈₉ Ni ₈ Mm ₃ (Mm is misch metal, numerical values are atomic%) was prepared, and then Al alloy powder was produced by the same method as in Example 1, Then, the same classification treatment as in Example 1 was performed.

The Al alloy powder was subjected to X-ray diffraction and differential calorimetric analysis (DSC), and its structure was examined. As a result, it was a mixed phase structure composed of a crystalline phase and an amorphous phase, and an amorphous phase. The crystallization temperature Tx was found to be 623K.

Next, various molded products were manufactured by using the Al alloy powder in the same manner as in Example 1.

Table 5 shows the degassing conditions and the characteristics of various molded products.

[0033]

[Table 5] In Table 5, molded bodies (32), (34) to (36),
In (39), (40), (42), and (45), the temperature T ₁ of the primary degassing process is Tx-100K ≦ T ₁ ≦ Tx + 15.
Satisfies the condition of 0K, also a high strength because the temperature T ₂ of the second degassing process satisfies the condition of _{T 1 -50K ≦ T 2 ≦ T} 1 + 150K.

The molded body (31) is the molded body (1) of Example 1.
Similarly, it has low strength. The temperature difference between the temperature T ₁ of the primary degassing treatment and the temperature T ₂ of the secondary degassing treatment is too small in the molded body (31), and the primary degassing is performed in the molded bodies (33) and (45). The treatment time is too short, and the molded bodies (37) and (38) are not sufficiently crystallized by the primary degassing treatment. In the molded bodies (41) and (43), the time for the secondary degassing treatment is too long.

The present invention is also applicable to an Al alloy powder having an amorphous single phase structure.

[0036]

According to the present invention, the degassing process is divided into two stages and the temperature in each process is specified, whereby the removal of hydrogen gas and the suppression of the destruction of the fine structure by rapid solidification can be achieved. This makes it possible to obtain a high-strength molded product.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the time of secondary degassing treatment and tensile strength.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

[0015]

[Table 1]In Table 1, the molded bodies (3) to (5) are the primary degassing treatments.
Reason temperature T₁Is Tx-100K ≦ T₁≤Tx + 150K
And the temperature T of the secondary degassing process ₂ButT ₁
+ 50K ≦ T ₂ ≦ T ₁ + 150KMeets the conditions of
So it has high strength.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

[Table 2] In Table 2, the molded body (4a) ~ (6a), the temperature T ₁ of the primary degassing process _{Tx-100K ≦ T 1 ≦ Tx} + 15
The temperature T ₂ of the secondary degassing process satisfies the condition of 0K.
Since the condition of T ₁ + 50K ≦ T ₂ ≦ T ₁ + 150K is satisfied, the strength is high.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0033

[Correction method] Change

[Correction content]

[0033]

[Table 5] In Table 5, molded bodies (32), (34) to (36),
In (39), (40), (42), and (45), the temperature T ₁ of the primary degassing process is Tx-100K ≦ T ₁ ≦ Tx + 15.
The temperature T ₂ of the secondary degassing process satisfies the condition of 0K.
Satisfies the condition of T ₁ + 50K ≦ T ₂ ≦ T ₁ + 150K ,
Further, the primary and secondary degassing treatment times also satisfy the above-mentioned conditions, so that the strength is high.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

The molded body ( 30 ) is the molded body (1) of Example 1.
Similarly, it has low strength. In the molded body (31), the temperature difference between the temperature T ₁ of the primary degassing treatment and the temperature T ₂ of the secondary degassing treatment is too small, and in the molded bodies (33) and ( 44 ) the primary degassing short time of processing or too, further moldings
In ( 38), the temperature T ₂ of the secondary degassing process is high.
Squeeze. Adult form (41), the time of the secondary degassing process too long in (43).

Claims (1)

[Claims] 1. An Al alloy powder having an amorphous phase whose crystallization temperature is Tx has a temperature T ₁ of Tx-100K ≦ T ₁ ≦
A primary degassing treatment is performed under the condition of Tx + 150K to change the phase of the amorphous phase into a crystalline phase, and then the Al alloy powder having a temperature T ₂ of T ₁ + 50K ≦ T ₂ ≦ T ₁ +150.
Secondary degassing treatment is performed under the condition of K. A
Degassing of alloy powder.