KR20030049866A - Ductile Particle Reinforced Amorphous Matrix Composite and Method for Making the Same - Google Patents

Abstract

PURPOSE: An amorphous matrix composite is provided in which ductile particles are reinforced through manufacturing process for integrating the mixed powder after mixing amorphous powder with a certain amount of ductile powder, and a method for manufacturing the same is provided. CONSTITUTION: The ductile particle reinforced amorphous matrix composite is characterized in that ductile powder is dispersed into amorphous powder so that the mixed powder is integrated, wherein the amorphous powder includes all alloy systems that can be manufactured of amorphous powder, wherein the ductile powder includes all types of material having strain stress lower than strain stress generated when forming the amorphous powder in supercooling zone, and wherein the ductile powder is contained in the composite in the range of 0.1 to 40 vol.%. The method for manufacturing the ductile particle reinforced amorphous matrix composite comprises the steps of preparing a mixed powder by mixing amorphous powder with ductile powder; obtaining a billet compacting the mixed powder in the state that the mixed powder is sealed in a container; and integrating the mixed powder by processing the billet at a temperature of amorphous supercooling zone, wherein the amorphous powder includes all alloy systems that can be manufactured of amorphous powder, wherein the alloy system is any one alloy system of Ni-matrix, Ti-matrix, Zr-matrix, Al-matrix, Fe-matrix, La-matrix, Cu-matrix, or Mg-matrix, wherein the ductile powder includes all types of material having strain stress lower than strain stress generated when forming the amorphous powder in supercooling zone, wherein the ductile powder is contained in the composite in the range of 0.1 to 40 vol.%, and wherein the integration step of the mixed powder is performed by hot extrusion or hot forging.

Description

Ductile Particle Reinforced Amorphous Matrix Composite and Method for Making the Same

The present invention reduces the formation of fine pores by incorporating a certain amount of ductile powder to amorphous metal powder by integrating the powder through hot extrusion and hot forging, and improves the fracture toughness by improving the elongation of the manufactured composite material, The present invention relates to an amorphous matrix composite reinforced with soft particles which can be enlarged and diversified in an amorphous material, thereby making a large-scale high-quality, high-strength product, and a manufacturing method thereof.

Amorphous materials exhibit high strength mechanical properties below the amorphous transition temperature. For example, in the case of amorphous Ni-, Ti-, and Zr-based bases, the fracture strength is about 2 GPa, and in the case of Al-bases, it is about 1 GPa. This high strength property is due to the unusual atomic structure of the amorphous material, and therefore the possibility of application to high quality structural materials is endless.

However, the above-mentioned alloys having excellent amorphous formability are limited in the size that can be produced. That is, these alloys can be obtained by cooling the molten metal to obtain an amorphous structure even under relatively low cooling conditions (1-250 K / s), but the diameter is about 10 mm in size. In addition, the amorphous material is hardly ductile at or below the amorphous transition temperature, and even though it is ductile, a shear strain band is formed and strain hardening does not occur and is suddenly broken (A. Inoue, Prog. Mat. Sci., 43 (1998) 365).

First, a method of preparing amorphous powder and integrating it by hot extrusion as a method for solving the problem of size is disclosed in US Pat. No. 4,523,621. The preceding patent manufactures a powder under quenching conditions by a gas atomization method, and selects only amorphous powder, which is contained in a Cu container and sealed, and then extruded or forged at a temperature above an amorphous transition temperature. It is a method of making an integrated amorphous material without limiting the size.

In this method, it is difficult to bond between powders under conditions where the amorphous phase is not crystallized. In other words, in order to prevent the crystallization of the amorphous phase during powder production, the extrusion ratio cannot be increased, and in general, an oxide film is formed on the surface of the amorphous powder. The pores are present between the particles.

In order to prevent this oxide film formation, manufacturing costs increase because all the manufacturing processes must be performed in a special atmosphere such as Ar gas or vacuum. In addition, the specimen should be quenched after extrusion to prevent the phase change due to heat (ie, crystallization) as much as possible.

Next, whether it is manufactured by integrating the powder or by quenching the molten metal, all of the amorphous materials exhibit sudden breakdown as mentioned above. Is required.

Various methods have been proposed to solve this problem of fracture toughness. For example, an amorphous matrix composite material (RD R Conner, RB Dandliker and WLJohnson, Acta Mater., 46 (1998) 6089) in which ceramic or metal particles are mixed and quenched in a melt to disperse particles, Composites prepared by permeating cooling the molten wire after arranging the stern wires (see US Patent No. 6,010,580), by adjusting the rate of solidification, a material in which a soft phase is first formed during solidification and the rest becomes amorphous (CC Hays, CP Kim and WL Johnson, Proc. ISMANAM.ISMANAM-99, Mater. Sci.Forum, Dresden, Germany, 2000). However, in the above case, although the elongation can be improved, there is a size limitation because it forms amorphous when the molten metal solidifies.

Therefore, the present invention has been proposed to solve the problems of the size, shape, fracture toughness, manufacturing process of the above, the object is to mix the soft powder with the amorphous powder particles in an appropriate ratio and then mix the mixture to seal the amorphous transition temperature As described above, the present invention provides a composite material in which a certain amount of amorphous metals and soft powders are deformed in a predetermined amount by extrusion or forging in a temperature condition below the crystallization temperature (i.e., a supercooling zone) so that the soft metal particles are dispersed in an amorphous base in a predetermined amount, and a manufacturing method thereof There is.

The present invention provides a selection of a soft powder according to an amorphous material, a mixing ratio of an amorphous powder and a soft powder, a production method for integrating these, and a manufacturing condition.

1 is an X-ray diffraction graph of 10, 45, 75, 106 and 150 μm sized amorphous particles and ribbon shaped samples obtained from Ni ₅₉ Zr ₂₀ Ti ₁₆ Si ₂ Sn ₃ ;

FIG. 2 is a graph of thermal properties of powders of 10 μm and 45 μm in the powder of FIG. 1;

3A and 3B are tissue photographs of a cross section and an extrusion direction surface of the amorphous matrix matrix sample of Example 1 each containing 10 vol.% Of copper particles,

4 is an X-ray diffraction graph of the composite of Example 1 (10 vol.% Cu) and Example 3 (30 vol.% Cu),

5 is a graph showing the stress-strain relationship of the compression test results of the composite samples of Examples 1 to 3.

6 is an electron scanning (SEM) photograph of the fracture surface of the composite sample according to the present invention.

In order to achieve the above object, the present invention provides an amorphous matrix composite, characterized in that the soft powder is dispersed and integrated in the amorphous powder.

Amorphous alloys used in the composite include all alloy systems from which amorphous powders can be produced, for example Ni-, Ti-, Zr-, Al-, Fe-, La-, Cu-, Mg-based Alloy systems such as these may be used.

The soft powder is mixed with all kinds of materials having a lower strain stress than that of the amorphous powder when molded in the supercooled zone, that is, the amorphous particles do not crystallize when the amorphous particles are extruded and forged in the supercooled zone, It is set as a material that is more deformed than the amorphous particles to assist in the integration of all the particles.

The reason why the soft powder is set to a material having a lower strain stress than that of the amorphous powder is that the amorphous material deforms the viscose when the amorphous powder is deformed in the supercooled zone. The same or more variations should be made.

In this case, of course, this purpose can be achieved only if the deformation stress of the soft powder is lower than the flow stress of the amorphous powder. If the deformation stress of the powder is high, the soft powder is not deformed. Maintaining the shape as it is, or deformed much less than the amorphous powder, the bonding strength of the interface between the soft powder particles and the amorphous particles, or the pores are formed between the interfaces adversely affect the mechanical properties of the material.

The content of the ductile powder should be set as a range capable of improving the elongation without significantly reducing the strength compared to that produced only with amorphous powder after the preparation of the composite.

In order to achieve this object, the content of the soft powder is preferably set in the range of 0.1vol.% To 40vol.% Where the contact between the soft component powder does not occur, or even if the contact is not severe and less affect the mechanical properties.

First, when the content of the soft powder is 50 vol.% Or more, the content of the soft powder should be less than 50 vol.% Because it becomes a soft powder-based base rather than an amorphous base.

In general, when the content of the powder is more than 30% (which is a general characteristic when the powder is mixed), agglomeration phenomenon occurs between the soft particles, which makes it difficult to achieve the desired purpose. That is, each of the soft particles added may be separated and dispersed in the amorphous matrix to obtain the maximum effect.

However, in the present invention, the upper limit content of the soft powder is set to 40 vol.%, Even if the content is 30 vol.%, As shown in FIG. 5 to be described later. This is because the phenomenon of aggregation depends on the mixing technology of the powder particles. The reason why the lower limit content of the soft powder is set to 0.1 vol.% Is because the effect of mixing is hardly exhibited when it is less than 0.1 vol.%.

In addition, since the soft powder is set as a material having a lower strain stress than that of the amorphous powder at the time of molding, regardless of whether the initial soft powder particles are fiber or spherical, the size is also initial amorphous. As long as it can be mixed with the powder, it does not matter, so it is not limited by the size or shape of the particles.

According to another feature of the present invention, the present invention provides a method for producing an integrated amorphous matrix composite wherein the soft powder is dispersed in the amorphous powder.

The method for producing an amorphous matrix composite of the present invention comprises the steps of dispersing and mixing a predetermined amount of soft particles into the amorphous particles selected as described above, and compressing the soft mixed powder in a sealed state in a container to obtain a billet. And the step of integrating the billet by processing at the temperature of the amorphous subcooling zone.

The billet described above can be integrated of all particles, for example by a hot extrusion or forging process, in which case the amorphous particles must not crystallize and remain in the amorphous phase.

The amorphous matrix composite obtained by the above method is produced as a final product through a process such as forming, for example, in machining, discharging or subcooling.

As described above, the amorphous matrix composite prepared according to the present invention can reduce fine pore formation generated in the process of integrating only amorphous powder because it contains soft particles, compared with conventional amorphous materials made only of amorphous powder. Soft particles act as the starting point of shear deformation, and can prevent crack propagation, thereby improving elongation at room temperature, thereby improving fracture toughness, which has been a problem in the conventional amorphous powder only material.

In addition, in the present invention, compared to the conventional hardened amorphous material, molten amorphous mixed base material prepared by mixing the particles in the molten metal and then the size limitation can be removed to increase the size and diversification, large-scale high-quality, high-strength product It can be widely used to make

If the present invention will be described in detail based on the examples as follows, the present invention is not limited to the examples.

<Examples 1 to 3>

Ni-based alloys (Ni ₅₉ Zr ₂₀ Ti ₁₆ Si ₂ Sn ₃ , atomic%) having excellent amorphous forming ability were induced and dissolved in argon atmosphere to prepare a master alloy and solidify it, and then in a gas atomization furnace. After dissolution, powder was prepared through a 3.2 mm diameter nozzle. At this time, the pressure was about 2.8MPa and the temperature of the liquid phase was about 1623K. The powders were sorted at intervals of about 10 μm because they exhibit a range of sizes ranging from less than 10 μm to more than 150 μm.

FIG. 1 shows the results of diffracting X-rays of 10, 45, 75, 106 and 150 μm sized amorphous particles and ribbon-shaped samples obtained from Ni ₅₉ Zr ₂₀ Ti ₁₆ Si ₂ Sn ₃ . It can be seen that crystallization occurred in powder having a size of 45 μm or more. Therefore, only powders up to 45 μm in size were used in subsequent tests.

Next, the thermal characteristics of the powders of the 10μm and 45μm size of the powders obtained by using a thermal analyzer (DSC: differential scanning calorimetry) is shown in FIG. The thermal characteristic graph is obtained by continuously heating the powder at a heating rate of 30 K / min using a thermal analyzer. The graph shows that the amorphous transition temperature (Tg) is 815K and the crystallization temperature (Tx) is 878K. Therefore, the interval of integrating the powder is set between the two temperatures, that is, the subcooling temperature of 848 K. When the ram speed is 0.48 cm / sec during extrusion at this temperature, the strain stress of the amorphous powder alone is 510 MPa through experiments. there was.

Accordingly, the selection of the soft powder selected a copper (Cu) powder having a very low strain stress than the amorphous powder in these manufacturing conditions. Copper powder having a size similar to that of the amorphous particles was contained in the amorphous powder by 10 vol.%, 20 vol.%, And 30 vol%, respectively, and then mixed with the amorphous powder to prepare a mixed powder of Examples 1 to 3. Thereafter, the powder mixture of Examples 1 to 3 was separately charged into a copper pipe having an internal diameter of 125 mm, and then compacted by applying pressure at room temperature in a vacuum sealed state to obtain three billets. Thereafter, the billets were rapidly heated to an extrusion temperature of 848 K, and then cooled in air after extrusion under conditions of a ram speed of 0.48 cm / sec and an extrusion ratio of 5 to prepare samples of Examples 1 to 3. The prepared amorphous matrix composites of Examples 1 to 3 are 25 mm in diameter and 100 mm in length.

3A and 3B are tissue photographs of the cross-section and extrusion direction surface of the amorphous matrix composite sample of Example 1, each containing 10 vol.% Of copper particles, in which copper particles are dispersed in the amorphous matrix at regular intervals (FIG. 3A). At first, spherical copper particles are deformed and distributed in the extrusion direction (Fig. 3b).

FIG. 4 shows the results of diffraction of the composites of Example 1 (10 vol.% Cu) and Example 3 (30 vol.% Cu) on X-rays. Shows that there is. In addition, here, "Monolithic" is also shown as a result produced only with amorphous powder. The same trend was observed for other 20 vol .-% copper composites.

In FIG. 5, the compressive test results of the composite samples of Examples 1 to 3 are shown in a stress-strain relationship. Here, "Monolithic" is also shown as a result produced only with amorphous powder. In the case of amorphous powder only, it exhibits a breaking strength of about 2.0 GPa, which is almost similar to that of the quench solidified amorphous powder (2.2GPa).

Referring to FIG. 5, as the amount of copper is increased, the stress tends to decrease slightly as expected, but the plastic strain causes the elongation to increase. This plastic deformation, i.e., an increase in elongation, is a very important factor that makes it possible to use an amorphous material as a structural material, which is a property that hardly appears in the case of an amorphous material manufactured by integrating powder until now. In the absence of plastic deformation, it is generally impossible to predict under what conditions the material will break, and it is difficult to apply structural materials.

However, if the high-strength amorphous material contains a ductile metal phase therein as in the present invention, the plastic phase of the material may cause plastic deformation in various places because the metal phase may act simultaneously as a starting point of shear deformation or as an obstacle to propagation of shear deformation. Plastic deformation as a whole, and thus fracture toughness is improved.

Finally, FIG. 6 is an electron scanning microscope (SEM) of the fracture surface of the composite sample according to the present invention, wherein the amorphous pattern of the fracture pattern (vein pattern) is observed in various places, and also the powder particles It shows the shape broken apart. That is, in the composite according to the present invention, it is judged that the ductile fracture and the brittle fracture are combined.

In the above embodiment, only the Ni-based alloy has been described as an example. However, the embodiment was manufactured using viscose flow in a subcooled zone, which is a basic characteristic of amorphous material. Since it is an inherent characteristic to appear, it is similarly applied to other alloy systems.

As described above, in the present invention, a composite having no size limitation can be obtained through a method of manufacturing hot extrusion or forging in which soft particles are dispersed in an amorphous powder to integrate all particles, thereby rapidly cooling a conventional molten metal and preparing the same. It solved the problem of size limitation which was a problem.

In addition, the present invention can improve the toughness of the amorphous material with almost no decrease in strength due to the addition of the soft phase to the problem of the toughness, which was a problem when manufacturing only the amorphous powder, and can be used as various high strength and high quality structural materials. It is effective to make it possible.

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments and is not limited to the spirit of the present invention. Various changes and modifications can be made by those who have

Claims (10)

An amorphous matrix composite reinforced with soft particles, wherein the soft powder is dispersed and integrated in the amorphous powder. 2. The amorphous matrix composite of claim 1, wherein the amorphous powder comprises all alloy systems that can be made of amorphous powder. 2. The amorphous matrix composite of claim 1, wherein the ductile powder comprises all kinds of materials in which the amorphous powder is lower than the strain stress upon molding in the subcooled zone. The amorphous matrix composite according to any one of claims 1 to 3, wherein the soft powder contained in the composite is included in the range of 0.1 vol.% To 40 vol.%. Preparing a mixed powder by mixing the amorphous powder and the soft powder, Compressing the mixed powder in a sealed state in a container to obtain a billet; And processing the billet at the temperature of the amorphous subcooling zone to integrate the mixed powder. 6. The method of claim 5, wherein the amorphous powder comprises all alloy systems that can be made of amorphous powder. The method of claim 6, wherein the alloy system is any one of Ni-, Ti-, Zr-, Al-, Fe-, La-, Cu-, and Mg-based alloys. . 6. The method of claim 5, wherein the soft powder comprises all kinds of materials in which the amorphous powder is lower than the strain stress upon molding in the subcooled zone. The method according to any one of claims 5 to 8, wherein the soft powder contained in the composite material is included in the range of 0.1 vol.% To 40 vol.%. The method of claim 5, wherein the integrating of the mixed powder is performed by hot extrusion or hot forging.