JPS60159137A - Manufacture of cast aluminum alloy containing dispersed hyperfine ceramic particles - Google Patents

Abstract

PURPOSE:To manufacture easily the titled cast Al alloy at a low cost by adding an element for improving the wetting property of a molten Al alloy to ceramic particles to the molten Al alloy before dispersing hyperfine ceramic particles in the molten Al alloy. CONSTITUTION:The wetting property of molten Al or a molten Al alloy to ceramic particles is improved by adding 0.05-2.0atom% Zr or Nb, 0.1-3.0atom% Ti, Ca, Cr or V, or 0.2-3.0atom% Mg to the molten metal. To the molten metal are than added 1-50vol% hyperfine ceramic particles of <=5mum particle size such as carbide particles of SiC, TiC, VC or NbC, oxide particles of Al2O3, Cr2O3, ZrO2 or Y2O3, or nitride particles of Si2N4, AlN, TiN or BN, and the particles are dispersed. Thus, a large amount of dispersed particles is easily contained in the molten metal.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is directed to the use of molten aluminum or aluminum alloy containing ultrafine carbide, nitride, or oxide ceramic particles of 5 μm or less in an amount of up to 50% by volume. The present invention relates to a method for manufacturing an aluminum alloy metal having ultrafine ceramic particles dispersed therein, which is suitable for dispersing ultrafine ceramic particles.

[Background of the invention]

Conventional particle-dispersed materials are manufactured by the following method. The main method is powder metallurgy, in which metal powder and ceramic powder are mixed in a ball mill, shaped, and sintered.

Creates an oxide coating on the surface of aluminum powder, molds it,
Surface oxidation method (SAPI), which is manufactured by sintering and processing, or mechanical method, which is manufactured by embedding dispersed particles in metal matrix particles using a ball mill such as an attritor mill, and then performing molding, extrusion processing, heat treatment, etc. Alloy method (ODS). Since these all use the number of paddy grains,
This method has disadvantages in that it tends to cause uneven distribution of dispersed particles or pores in the metal substrate, and the work process is complicated, making it unsuitable for mass production. There is also an internal oxidation method in which a metal element with a greater tendency to form oxides than the matrix is added to the 71 helix to create a solid solution, and the solute elements are selectively oxidized to disperse oxide particles. However, this method cannot uniformly disperse the oxide deep inside the metal.On the other hand, methods for directly dispersing dispersed particles in the molten metal include the injection dispersion method and the compocasting method. The injection dispersion method uses a powder injection device to forcibly inject and disperse solid oxide or solid sulfide powder with a particle size of 5 x 10-'co+ or less together with Ar gas into the molten steel flow while it is being poured into a mold.
It is rapidly cooled and solidified. This method has disadvantages, such as the fact that the injection amount and content are not constant, and that a large amount of dispersed particles cannot be dispersed. On the other hand, in the compocasting method, the molten metal is kept in a semi-molten state in the solid-liquid coexistence range, and the particles are mixed while mechanically stirring, and the presence of the same phase prevents the mixed particles from floating and separating. The major drawback of this method is that the material is in a semi-molten state, resulting in poor fluidity and impossibility of general mold casting. Therefore, since solidification occurs in the crucible, nonuniform distribution of mixed particles or many casting defects occur, and the ingot cannot be used as an ingot. Therefore, a processing step for the ingot after solidification is required, which is not economical.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the conventional method, and to create a carbide-based material by directly introducing and dispersing ultrafine ceramic particles into a molten aluminum alloy at a temperature of 30°C or higher above the liquidus line, and then rapidly solidifying the dispersed molten metal by pressure solidification. It is an object of the present invention to provide an aluminum casting alloy material in which nitride-based or oxide-based ultrafine ceramic particles are dispersed at a low cost and easily.

[Summary of the invention]

In addition to conventional methods, precipitation strengthening is commonly used as a method for increasing the strength of metal materials. The precipitation strengthening method can maintain hardness or strength up to high temperatures by precipitating fine compounds by subjecting a metal material of a certain composition to a predetermined heat treatment. However, the precipitated compound decomposes and disappears at temperatures above the heat treatment temperature, resulting in a sharp decrease in hardness or strength. For this reason, in order to have hardness or strength up to higher temperatures, it is necessary to replace the precipitates with oxide-based, nitride-based, or carbide-based fine particle compounds that have a higher melting point than the matrix and are stable at high temperatures. If it can be uniformly dispersed in the matrix, it is possible to produce high-temperature materials that can withstand higher temperatures compared to heat treatment precipitation methods. According to the present invention, Ca is added to aluminum or molten aluminum alloy in advance.
Ti.

After containing at least one line selected from Cr, Mglv, Zr, or Nb, oxide-based, nitride-based or carbide-based fine particles are added from the surface of the WJ hot water,
It has been found that a cast alloy material in which fine particles are uniformly dispersed in large quantities can be easily and inexpensively produced by solidifying a fine particle-dispersed molten metal. Furthermore, even if the cast alloy of the present invention is remelted or melted again, the dispersed particles remain in the molten metal without floating to the surface of the molten metal. The present invention will now be described in detail. The most important aspect of the method of the present invention is to disperse fine ceramic particles in the molten metal. Here, molten metal or melting means a temperature of 30° C. or higher above the liquidus line. In the usual method, even if fine particles are added from the surface of the molten metal, the introduced particles float and separate on the surface of the molten metal, making it impossible to form a dispersed molten metal. To prevent this, in the method of introducing and dispersing fine particles from the surface of the molten metal, the key point in suppressing floating separation of the additive particles is to wet the molten metal with the particles. The type of dispersed particles considered in the present invention is SiC.

T i C, VC, N b G (7) Carbide particles, AQ
20. .

Cr, O:l, ZrO, Y2O3 oxide particles, St
, N, , AIAN, TiN, and BN nitride particles.

The particle sizes are all 16 μm to 0.05 μm. As a result of various studies on methods of dispersing these particles into molten aluminum or aluminum alloy, we found that Ca was present in the molten metal in advance.

It was confirmed with good reproducibility that floating of various ceramic particles was prevented by adding at least one selected from Ti, Cr, Mg, V, Zr, and Nb. In other words, all the oxide-based, nitride-based, and carbide-based particles in the molten metal to which Ca and Zr were added were dispersed in the molten metal without floating and separating on the surface of the molten metal. Also Ti, Cr, V and Nb
Oxide and nitride particles were dispersed in the molten metal to which the molten metal was added, but carbide particles floated on the surface of the molten metal and separated into two. On the other hand, only oxide-based particles were dispersed in the Mg-added molten metal, and other carbide-based and nitride-based particles floated and separated on the surface of the molten metal.

Re-adding metal elements to disperse particles in molten aluminum and aluminum alloys is effective for Zr and N, respectively.
In the case of b, 0.05 to 2.0 at%, Ti, Ca, Cr
and 0.1-3.0 atom% for V and 0 for vMg
．． The content is preferably 2 to 3.0 at%. If the amount of each added metal element is below the lower limit, particles cannot be dispersed in the molten metal. Further, each upper limit amount is sufficient to disperse various types of dispersed particles up to 50% by volume, and if the upper limit is exceeded, the respective added metal elements and needle-like compounds of AQ will crystallize and make the material brittle. Further, the melting point of the matrix is also higher than 1000°C, which is not practical.

Although it is not necessary to pay attention to the selection of the sizes of the various particles that can be dispersed in the molten metal using the method of the present invention, in this experiment, we investigated down to the smallest available particle size of 0.05 μm and confirmed that the particles could be dispersed. In reality, the particle size and type of dispersed particles should be selected depending on the intended use of the material.

The amount of various particles that can be dispersed in the molten metal by the method of the present invention is 50% or less by volume. Even if 50% or more of the particles are introduced and dispersed in the molten metal, the dispersed molten metal has almost no fluidity, and therefore has poor castability and cannot produce a sound ingot.

In addition, the particle-dispersed molten metal obtained by the method of the present invention is subjected to a rapid solidification method.
For example, a more sound ingot can be obtained by using a water-cooled mold solidification method or a pressure solidification method.

[Embodiments of the invention]

The present invention will be explained in detail below.

Example 1 SiC particles 2 with a particle size of 1 μm were collected from the surface of 380 g of pure aluminum molten metal held at 750° C. in a graphite crucible in the atmosphere.
Using two φ6×φ8×60Q alumina protection tubes, 0 g of the SiC particles was poured into the center of the vortex while stirring the molten metal, and the dispersibility of the SiC particles was investigated. The molten metal after the study was cast into a mold while stirring the molten metal. Dispersibility can be easily determined by visual observation because the state of the molten metal dispersed during melting is almost the same as that of ordinary molten metal, and when it is not dispersed, the additive particles float and separate on the surface of the molten metal. As a result, the SiC particles added were not dispersed in the molten metal, but floated and separated on the surface of the molten metal. Similarly, T i C (2-3 μm
), VC (2-3 μm) vNbC (2-i μm
), AM203 (1pm.

2 types of 0.05pm) r Car2ox (1~2pm
) Z r O, (1-2 p m ), Y 20.
(2-3 μm)+S i, N4 (0.5-0.3.
um), AQN (4.9-4.5 μm), T
i N (4.9-4.0 μm) and BN (1-0.
As a result of adding various particles (5 μm), none of the particles were dispersed in the molten metal, but floated and separated on the surface of the molten metal.

Example 2 After melting pure aluminum using a graphite crucible in the atmosphere,
380g of metal Ca added to 1.0 atomic%
The molten metal is maintained at 750°C. 20 g of SiC particles with a particle size of 1 μm were added to the surface of the retained molten metal in the same manner as in Example 1, and the dispersibility of the SIC particles was examined. As a result, the added SiC particles were dispersed into the molten metal without floating to the surface of the molten metal. Similarly, TiCtVC
tNbC, An, 03 (2 types), Cr2O,, ZrO.

Y201 p S 1 a N4 p AQN? T
The effect of adding Ca to each particle of iN and BN was investigated. As a result, all particles were dispersed in the molten metal. Therefore, we investigated the effects of added metal elements on the dispersibility of various particles. Additional metal elements are tvlg, Ti, and Cr.

Z r p V v P t M r+ HS i and Nb. Note that metal elements other than Mg, P, and St are AQ.
A mother alloy was used. Further, the amounts of added metals are each constant at 1.0 atomic %. The experimental method was the same as in Example 1. Table 1
is a summary of the results including Example 1.

In the table, the x mark indicates floating separation on the surface of the molten metal, and the ○ mark indicates dispersion into the molten metal. As can be seen from Table 1, all particles float and separate in pure aluminum molten metal. Also, P, Si,
It can be seen that each metal element of Mn also has no effect on dispersion. On the other hand, it can be seen that addition of Ca and Zr into the molten metal is effective for oxide-based, nitride-based, and carbide-based particles. However, it can be seen that Ti, V and Nb-added molten metals are effective in dispersing oxide and nitride particles, but are not effective in dispersing carbide particles. Moreover, Mg-added molten metal is effective for oxide particles, but is not suitable for dispersing nitride and carbide particles.

Example 3 In Example 3, the influence of the dispersed particle size on the maximum amount of dispersion was investigated. The particle size is 0.5 to 16 μm for SiC particles, 0.5 to 16 μm.
05 μm is AΩ, and the 0-dispersion molten metal composition studied using 03 particles is AQ-3, 0 atomic % Ca. The experimental method involved melting pure aluminum in a graphite crucible in the atmosphere, and then holding 400 g of molten metal at 750° C. to which metallic Ca was added at 3.0 at%. The retained molten metal is φG×φsr
; Stir using two alumina protection tubes turned on, and add 1.0 g of particles of various particle sizes to the center of the vortex so that they are densely packed.
Hold for a minute and observe dispersion. By repeating this process, the maximum amount of dispersion was determined. The maximum amount of dispersion was defined as the time immediately before the dispersed molten metal could not be cast. Figure 1 summarizes the results converted into volume percentages.

As can be seen from FIG. 1, the amount of dispersion is approximately constant at 48% for particles with a particle size of 3 μm or more as a boundary, and as the particle size becomes finer, the amount of dispersion decreases to 36% at 0.05 μm.

Example 4 In Example 4, the influence of the matrix on dispersibility was investigated. The dispersed particles are SiC with a particle size of 0.5 μm. The matrix is A Q -12S i -3Cu -0, 3M
g series, AQ-8Sn-2Cu-0,5Mg series.

AQ-4Cu-1,5Mg 4Pb-based JIS standard C-based ADC-based and AJ-based alloys. Further, Zr is used as an additive element for particle dispersion, and the amount added is 1.0 atomic %. The experimental method was to melt various matrices in the atmosphere using a graphite crucible, and then melt Zr using AQ-9, 8% Zr master alloy.
360 g of molten metal added so that the amount of molten metal is 1.0 at% is maintained at 800°C. The held molten metal is φ6×φ8×6
Using two 0Q alumina protection tubes, 40 g of SiC particles were poured into the center of the vortex while stirring, and the dispersibility of the SiC particles in each matrix was examined. As a result, the SiC particles in each matrix were dispersed in the molten metal without floating and dispersing.

Further, as a result of observing the distribution state of SiC particles in the ingot using an electron microscope, no difference was observed depending on the matrix.

Example 5 Example 5 shows the AQ-L dispersed in the molten metal in Example 2.
The state of SiC particles during remelting using an O atomic % Ca-5% SiC ingot and the effect of pressure solidification using the same molten metal were investigated. As a result, the state of the SiC particles at the time of remelting was such that even after remelting, the SiC particles in the molten metal did not float and separate and remained in the molten metal. The same result was obtained even when the mixture was re-dissolved. On the other hand, the remelted molten metal was solidified under pressure, and the distribution of SiC particles in the ingot and the soundness of the ingot were examined. In the pressure solidification method, the dispersed molten metal was cast into a split mold preheated to 300° C. while stirring, and solidified while being pressurized at 600 kg/cj from the top of the split mold with a plunger. As a result of observing the cross section of the ingot, the distribution state of SiC particles was almost uniformly distributed over the entire surface of the ingot, and no casting defects were observed.

As is clear from the examples below, as a method for dispersing oxide-based, nitride-based, and carbide-based fine particles into aluminum and aluminum alloy ingots, Ca, Tt,
It has been found that this can be achieved by adding at least one selected from Cr, Mg, V, 'Nb, Mg and Zr.

〔Effect of the invention〕

According to the present invention, since it can be manufactured using a general casting method, complicated processes can be omitted compared to powder metallurgy methods or internal oxidation methods, and complex shapes and large shapes can be easily produced, and it is suitable for mass production. ing. Further, since a large amount of dispersed particles can be dispersed, various properties are improved, and the product can be manufactured at low cost.

[Brief explanation of drawings]

Claims (1)

[Claims] (1) In a method of dispersing oxide-based, nitride-based, and carbide-based ultrafine ceramic particles of 5 μm or less in a range of 1 to 50 volume % into a molten aluminum or aluminum alloy. , Ca and Ti are added to the molten metal before adding the various ceramic particles. Ultrafine ceramic particles selected from Cr, Mg+v, Zr and Nb and containing at least one element that causes wetting of the molten metal and the ceramic particles before adding and dispersing the ceramic particles. Method for producing dispersed aluminum casting alloys. 2. Scope of the Claims In FIG. 1, the molten aluminum or aluminum alloy contains 0.05-3.
0 at% of Ca, Ti, Cr+ Mg+V, Zr and N
Ultrafine ceramic particle dispersion, characterized by dispersing the above-mentioned ultrafine ceramic in a molten metal containing at least one selected from b, and casting the particle-dispersed molten metal in a temperature range of 50 to 200°C above the liquidus line. Method of manufacturing aluminum casting alloy. 3. In claim 1, after containing at least one selected from Ca or Zr in the aluminum or molten aluminum alloy, SiC, VC
,Tic,NbC,AQz 01°Cr2O3,Zr
O,, Y, O,, Si3N4+AflN, TiN and B
A method for producing an aluminum casting alloy in which ultrafine ceramic particles are dispersed, characterized by adding and dispersing ultrafine particles of N. 4. In claim 1, the aluminum or aluminum alloy molten metal contains Ti. AQz Ox , Cr2o, ZrO, after containing at least one selected from Cr, V, and Nb. Adding and dispersing ultrafine particles of Y2O5t Si3N4 yΔQN, TiN, and BN; -1 Adding and dispersing VC particles into the molten metal containing V and NbC particles into the molten metal containing Nb other than the ceramic particles. A method for producing an aluminum ram casting alloy containing ultrafine ceramic particles dispersed therein. 5. In claim 1, after Mg is included in the aluminum or molten aluminum alloy, Af120. , Cr=o, , ZrO3°Y20B A method for producing an aluminum casting alloy containing dispersed ultrafine ceramic particles, characterized by adding and dispersing ultrafine particles of ZrO3°Y20B. 6. In claim 1, Cu, Sm. A method for producing an aluminum casting alloy containing ultrafine ceramic particles dispersed therein, characterized in that the above-mentioned ceramic is dispersed by cutting into an aluminum alloy containing at least one of PB and Si. 7. A method for manufacturing an aluminum alloy alloy in which ultrafine ceramic particles are dispersed, characterized in that the ceramic dispersed molten metal is solidified while being pressurized at 200 to 1,000 kg/cn.