JPH06235032A - Method for developing superplasticity of titanium carbide reinforced aluminum alloy composite material - Google Patents

Abstract

PURPOSE:To produce a composite metallic material having superplastic deformation by executing respective stages for mixing TiC particles and Al alloy powders in an org. solvent, then evaporating this solvent, sintering the mixture under pressurization and extrusion working the mixture. CONSTITUTION:The TiC particles of <=45mu grain size and Al alloy powders of 2000 system, 6000 system, 5000 system, 7000 system and 8000 system having <=45mu grain size are put into the org. solvent, such as ethanol, in such a manner that the volume content of the TiC powder attains from 0.10 to 0.30. The powders are then mixed uniformly together with plastic balls for 24 hours and thereafter, the solvent is evaporated. The powder mixture is sintered under pressurization by applying a pressure of a 200 to 500MPa range for 20 minutes thereto in a 450 to 600 deg.C range in a vacuum. Further, the powder mixture is extrusion worked at >=10 extrusion ratio in a 450 to 600 deg.C range and is rolled at need at 1.0 to 4.0 strain quantity in a 300 to 580 deg.C, by which the powder mixture is worked to the planar composite material of >=0.1mm thickness. As a result, the composite metallic material in which the superplastic deformation is developed is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy containing titanium carbide particles as a reinforcing material, which is also characterized by superplastic deformation.

[0002]

2. Description of the Related Art Ceramic whiskers or particle reinforced aluminum composite materials have a specific modulus of about 2 that of conventional metal materials.
The strength is twice as high as that of titanium alloy, and it has excellent heat resistance, wear resistance, thermal dimensional stability, and thermal conductivity. Is being applied to structures. Further, it is also expected to be applied to packages of electronic devices such as semiconductors.

In recent years, it has been found that ceramic whiskers and particle-reinforced aluminum composite materials develop superplasticity at a high strain rate of about 0.1 per second. In addition, by the efficient near net shape molding that utilizes this high-speed superplasticity phenomenon, in the aerospace field, etc., the establishment of a technology that can produce a three-dimensional structure with a complicated surface shape and a large surface area with high efficiency has been established. It has become possible.

However, the reinforcing material used in the conventionally developed superplastic ceramic whiskers or particle-reinforced aluminum composite materials is silicon carbide SiC or silicon nitride S.
i ₃ N ₄ ceramic whiskers or particles and aluminum nitride AlN particles only. The manufacturing method is S
After mixing iC or Si ₃ N ₄ and aluminum alloy powder, pressurizing and sintering, and further refine the matrix crystal grains by processing heat treatment (solution treatment-aging treatment-warm rolling-recrystallization treatment). Plasticity is developed. For example, a silicon carbide whisker reinforced 2124 aluminum composite material is formed into a plate shape by rolling after forging, and it is about 3 at about 0.2 per second.
Superplastic elongation of 50% has occurred. A silicon carbide particle reinforced 7064 aluminum composite was produced in the same manner as above, producing a superplastic elongation of about 500% at a strain rate of about 0.0001 per second. In addition, the inventors mixed fine aluminum alloy powder with a reinforcing material of silicon nitride whiskers and particles and aluminum nitride particles, and by powder metallurgy, a silicon nitride whisker and a particle-reinforced aluminum alloy composite material and an aluminum nitride particle-reinforced aluminum alloy. Alloy composite material was made. Silicon nitride whisker reinforced 2124, 606
For 1,7064 aluminum composite material, only extrusion, hot extrusion after forging, or rolling after extrusion was performed to achieve a total elongation of 250% to 600% at a strain rate of about 0.1 per second. . Then, the aluminum nitride particles AlN reinforced aluminum alloy composite material was subjected to hot extrusion and hot rolling, and found to have a total elongation of about 300% or more at a high strain rate of 0.03 to 1.0 per second. It was

Conventionally, research and development on superplasticity of an aluminum alloy composite material reinforced by SiC and Si ₃ N ₄ have been actively conducted. However, except that the inventors have found that superplasticity appears in AlN particle-reinforced aluminum alloy composite materials, there are almost no reports that show experimentally the possibility that superplasticity appears in general ceramic particle-reinforced aluminum alloy composite materials. Therefore, application of superplastic working to them was not considered.

[0006]

Silicon carbide SiC or silicon nitride Si is used as a reinforcing material for aluminum-based composite materials.
_{In addition to 3} N ₄ whiskers and particles, aluminum nitride AlN particles, titanium carbide TiC particles, alumina particles, boride TiB ₂ particles and the like are used. Among them, TiC particles are extremely hard as inferior to SiC, stable even at high temperature, and have high electric insulation. TiC particle reinforced composite materials are said to have high specific elastic modulus and high temperature strength. Therefore, it is expected that a high-strength composite material comparable to SiC, Si ₃ N ₄ whiskers, and particle-reinforced composite materials can be manufactured.
However, it was thought that the TiC particles react with molten aluminum to easily form brittle Al ₃ C ₄ , and superplasticity does not easily develop.

In order to develop superplasticity in these composite materials, at the superplasticity temperature, if slip deformation does not occur on the interface between the reinforcing material and the aluminum matrix, cracks will occur at this interface and large elongation cannot occur. become. Therefore, it is important for superplasticity expression that the crystal grains of the matrix are fine and that an interface that allows slip deformation at this interface is formed.

[0008]

In order to solve the above problems, therefore, in the present invention, in the process of producing an aluminum composite material containing titanium carbide particles as a reinforcing material, fragile Al at the interface between the TiC particles and the aluminum matrix. _The aluminum alloy is pressure-sintered in the solid state so as not to generate ₄ C ₃ . In the superplasticity development process of rolling after extrusion, the processing time was shortened as much as possible so that reaction products were not generated at the interface. Even if TiC particles do not form brittle Al ₄ C ₃ at the interface, they are the same carbides as silicon carbide whiskers and particles, so the chemical conditions under which the solid solution with low solidus temperature that allows sliding deformation at the interface can be formed. It is considered to be equipped. or,
It is considered that a thermo-mechanical treatment method combining extrusion and rolling gives mechanical conditions for forming a thin phase of an aluminum solid solution having a high concentration of magnesium Mg at the interface of the composite material. It is known that titanium carbide particles produce a reaction product such as Al ₄ C ₃ with an aluminum matrix. However, when aluminum is in a solid state,
Also, if the contact time with aluminum in a semi-molten state is short, a clean interface can be formed.

At the superplasticity temperature, the solid phase temperature of this solid solution is lower than that of the ground matrix, so that the matrix easily becomes a liquid phase even in a solid or semi-molten state. Slips easily occur. Further, the TiC particles suppress the coarsening of crystal grains at a high temperature, and the crystal grains of the matrix become fine. Due to these two effects, superplasticity is developed at high speed in this composite material. The superplasticity temperature is higher than the solidus line at which the liquid phase is generated at the interface between the TiC particles and the aluminum matrix, but since superplasticity is developed at a high strain rate, the aluminum solid solution in the liquid state at the interface and the TiC It is considered that the contact time with the particles is short and the generation of reaction products at the interface can be suppressed.

[0010]

EXAMPLES Examples of the present invention will be described below.

Example 1 Coarse TiC particles having an average particle size of 45 μm or less and 2124
The aluminum alloy powder has a TiC particle volume content of 0.
Diameter of 40 mixed by powder metallurgy
mm extruded from titanium carbide particles reinforced 2124 aluminum composite material at 500 ° C for 6 mm
Then, the material is wrapped in a stainless steel plate and a tube, heated in a temperature range of 500 ° C. to 580 ° C., and rolled at a small reduction rate such that the strain amount is about 0.1 or less. This is repeated and rolling is performed until the thickness becomes about 1 mm.

FIG. 1 shows the relationship between the deformation resistance and strain rate of this composite material. The tensile test temperature is 545 ° C. From FIG. 1, the strain rate sensitivity index of the deformation resistance of the titanium carbide particle reinforced 2124 aluminum composite material subjected to the rolling process after the extrusion process, the m value was 0.5 when the strain rate was 1.0 per second. Since the m value is 0.3 or more, this indicates that the composite material has undergone superplastic deformation.

FIG. 2 shows the relationship between total elongation and strain rate for the same composite material. From FIG. 2, the total elongation of the titanium carbide particle-reinforced 2124 aluminum composite material subjected to extrusion and rolling was 200% at a strain rate of 1.0 per second. It shows that the total elongation that can be practically used is generated. Example 2

Fine titanium carbide TiC having an average particle diameter of about 1 μm and 2014 aluminum alloy powder were prepared by pressure sintering, and extruded under the same conditions as in Example 1, and then rolled at 818K to obtain about 1 mm. A plate-shaped composite material having a thickness of. FIG. 3 shows the result of a tensile test conducted at a strain rate of 0.01 to 1.5 S ^-1 at a temperature of 818K.

FIG. 3 shows the relationship between strain rate and total elongation of a TiC particle reinforced 2014 aluminum alloy composite material. The total elongation is 350% at a strain rate of 1.3 S ^-1 , which indicates that superplasticity has occurred. Example 3

Coarse TiC particles having an average particle diameter of 45 μm or less and 6061 aluminum alloy powder were used for powder metallurgical production, and extruded at a temperature of 500 ° C. and an extrusion ratio of 44 to form a 6 mm bar, and then a temperature of 853 K ( (580 ° C)
Then, rolling was performed so that the thickness was 1 mm or less. FIG. 4 shows the relationship between the total elongation and the strain rate when the plate-shaped composite material was subjected to a tensile test at a temperature of 873K (600 ° C). This composite material also produced a total elongation of 200% or more at 1.5 per second, demonstrating that the TiC particle reinforced aluminum alloy composite material exhibits superplasticity at a significantly high strain rate.

[0017]

INDUSTRIAL APPLICABILITY In the present invention described above, the thin plate composite material is subjected to a tensile test at 545 ° C. to 600 ° C., and at a significantly high strain rate of 0.3 to 1.5 S ⁻¹ , 160% to 30%.
It was found that superplasticity with a high total elongation of 0% or more was developed. Therefore, a near net that efficiently molds a large structure in the aerospace field by superplastically forming a titanium carbide particle reinforced aluminum alloy composite material, which is expected to have high specific strength and high specific elastic modulus, at high speed. It is considered possible to establish shape molding technology.

[0018]

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between deformation resistance and strain rate when a tensile test is performed on a titanium carbide particle reinforced 2124 aluminum composite material at a temperature of 818K (545 ° C.).

FIG. 2 is a graph showing the relationship between total elongation and strain rate when a tensile test is performed on a titanium carbide particle reinforced 2124 aluminum composite material at a temperature of 818K (545 ° C.).

FIG. 3 is a graph showing the relationship between total elongation and strain rate when a tensile test is performed on a titanium carbide particle reinforced 2014 aluminum alloy composite material at a temperature of 818K (545 ° C.).

FIG. 4 is a graph showing the relationship between total elongation and strain rate when a tensile test is performed on a titanium carbide particle reinforced 6061 aluminum alloy composite material at a temperature of 600 ° C.

Claims (3)

[Claims] 1. Titanium carbide TiC particles having a particle size of 45 μm or less and 2000 series, 6000 series, 50 having a particle size of 45 μm or less.
00 series, 7000 series and 8000 series aluminum alloy powders were placed in an organic solvent such as ethanol so that the volume content of TiC particles was from 0.10 to 0.30, and mixed uniformly with plastic balls for 24 hours or more. After evaporating the solvent and applying a pressure of 200 MPa to 500 MPa to the mixed powder in vacuum at a temperature of 450 ° C. to 600 ° C. for 20 minutes and pressure sintering, the temperature is 450 ° C. to 600 ° C.
A method for producing a superplastic composite material, which has been extruded at an extrusion ratio of 10 or more at the temperature. 2. The composite material is rolled at a temperature of 300 ° C. to 580 ° C. with a strain amount of 1.0 to 4.0 to obtain 0.1 m
A method for manufacturing a superplastic composite material processed into a plate-shaped composite material having a thickness of m or more. 3. A superplasticity developing condition that causes a total elongation of 200% or more when a tensile test is performed on the composite material at a temperature of 450 to 600 ° C. at a strain rate of 0.03 to 1.5 per second or more.