JP2750824B2 - Method of joining whisker reinforced metal base material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a whisker-reinforced metal matrix composite material. More specifically, the present invention relates to a method for firmly bonding whisker-reinforced metal base materials to each other without damaging whiskers contained as a reinforcing material.

[0002]

2. Description of the Related Art Heretofore, a fusion welding method mainly using an arc heat source and a solid-phase welding method utilizing diffusion at a contact surface have been used for joining metal materials.

In recent years, with the technical development in many industrial fields including the aerospace industry, demands for new materials having higher heat resistance, strength, elastic modulus, and hardness have been increased. Metal matrix composites containing various reinforcements have been developed. As one of them, a metal-based composite material containing a whisker as a reinforcing material is known. This is considerably improved in terms of heat resistance and strength, but is inferior in workability, especially when the materials are fused and joined, the whisker of the reinforcing material is damaged by heat, and the improved characteristics are greatly improved. Lost or high temperature at the time of joining,
The whiskers near the joint surface are decomposed, solid-solved and disappear, resulting in a state in which no reinforcing material is present near the joint surface, resulting in a decrease in joint strength. In addition, when the solid-phase bonding method utilizing diffusion is used, diffusion of whiskers at the bonding interface does not occur, so that sufficient bonding strength cannot be obtained.

[0004]

SUMMARY OF THE INVENTION According to the present invention, when processing a metal base material reinforced with whiskers, the whiskers contained as a reinforcing material are joined together by a simple operation without damaging the whiskers. It is intended to provide a method.

[0005]

The present inventors have conducted various studies on the joining of a metal base material reinforced with whiskers. As a result, the metal phase constituting the matrix can be plastically deformed, but is fluidized. By contacting the two materials and applying pressure at a moderately high temperature, the two can be unexpectedly firmly joined together, and in this way, the function of the whisker existing as the reinforcing material is almost negligible. The inventors have found that this is not the case, and have led to the present invention based on this finding.

That is, according to the present invention, in joining two whisker-reinforced metal base materials, the surfaces of the materials to be joined are brought into direct contact without pretreatment, and the metal base materials are bonded in the air. The metal base material is heated to a temperature at which the metal phase constituting the matrix can be plastically deformed but not fluidized, and 10 to 300 M from the direction perpendicular to the contact surface between the two.
It is an object of the present invention to provide a joining method characterized in that both are joined through a whisker which is not substantially damaged by applying a pressure of Pa.

As the matrix of the metal-based material of the present invention, simple metals such as copper, nickel, cobalt, iron, silver, tin and magnesium and alloys thereof are used. It is particularly preferable to use a material requiring a high temperature for bonding.

Examples of such an aluminum alloy matrix include AC8A, AC1A, and ADC12. Among them, AC1A, in which the plastic deformability gradually increases with an increase in temperature, is preferred.

Whiskers added as a reinforcing material to these metals include, for example, whiskers such as silicon carbide, silicon nitride, potassium titanate, short alumina fibers, and aluminum borate. These may be used alone or in combination of two or more.

[0010] Of these, aluminum borate whiskers having a modest aspect ratio are particularly preferred.

The amount of the whiskers to be mixed with the above-mentioned metal matrix is 10 to 40% by volume based on the whole.
Preferably, it is selected in the range of 20 to 30% by volume.

In the method of the present invention, it is necessary to join at a temperature at which the metal phase forming the matrix can be plastically deformed, but does not flow. The joining temperature depends on the type of metal matrix used, but is in the range of about 500-600C, preferably 525-575C for aluminum alloys.

In the method of the present invention, the surfaces to be joined of the two whisker-reinforced metal base materials are brought into contact with each other, and then the temperature is maintained at the above-mentioned required temperature, and pressure is applied to the joint surface from the vertical direction. is necessary. The pressure at this time is usually 10 to 300 MPa, preferably 30 to 150 MPa.
The range of MPa is used.

As described above, when the whisker-reinforced metal base material is heated to a temperature near the so-called solidus line where the metal phase constituting the matrix is plastically deformable but not fluidized, and pressure is applied thereto, the matrix of the matrix is heated. The metal phase is plastically deformed, and the contained whiskers are joined while being dragged and moved to the plastic phase that is undergoing plastic deformation without dissolving and solidifying, so the joining is completed without generating whisker-free parts .

Accordingly, there is no damage to the whisker itself, and the joining is performed via the undamaged whisker, that is, without generating a portion where no whisker exists, and a strong joint can be formed.

[0016]

According to the present invention, a metal base material reinforced with whiskers can be joined without decomposing or dissolving the whiskers, and there is no whisker-free portion at the joint. A good bond can be formed.

[0017]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 An aluminum borate whisker [Albolex M12 manufactured by Shikoku Chemicals Co., Ltd.] was used as a surfactant with TX-1 as a surfactant.
00, a slurry containing polyvinyl alcohol and colloidal silica added as a binder was dehydrated under pressure to form a columnar preform containing 25% by volume of whiskers, and then ADC12 alloy was press-fitted into the preform by a melt forging method. A composite was made. The conditions for the forging of the molten metal are as follows: the preheating temperature is 700 ° C. for the preform and the ADC 12;
C., pressure 100 MPa, pressurization time 3 minutes. An uncomposite part around the obtained composite was scraped off with a lathe to obtain an original billet. This original billet was further divided into two parts in the horizontal direction with respect to the cylinder and subjected to a joining experiment. 10 for joining
Using a 0-ton hydraulic material testing machine, the billet was heated in a mold at a predetermined temperature for 30 minutes, pressurized with upper and lower punches, held at a predetermined pressure for 3 minutes, and then slowly unloaded and allowed to cool. A tensile test piece including the joint was cut out from the obtained joint pair, and a tensile test was performed. Table 1 shows the results. When the temperature was 500 ° C. or 575 ° C., the fracture occurred at the joint when the test piece was prepared, but when the temperature was 550 ° C., the strength was 298 MPa. This corresponds to a joint efficiency (relative value to the strength of the original billet) of 87%, indicating that a bond having sufficient strength was formed.

The attached drawings are optical micrographs showing the cross-sectional structure of the above-mentioned test piece at the joint at 575 ° C., FIG. 2 at the joint at 550 ° C., and FIG.
This is the junction at 25 ° C.

In FIG. 1, the temperature is too high, so that the matrix oozes out due to fluidization, and a band-like region without whiskers is observed.
3 and FIG. 3, it can be seen that there is no whisker-free portion in the joint portion, whiskers that are not substantially damaged are uniformly dispersed, and a strong joint is formed through the whisker. You.

[0021]

[Table 1]

Example 2 A preform having a whisker content of 25% by volume was prepared in the same manner as in Example 1, and was subjected to melt forging using an AC1A alloy and an Al-Zn alloy having the chemical composition shown in Table 2 by a melt forging method. A composite was produced by the method. A joining experiment was performed in the same manner as in Example 1 except that the temperature was set to 575 ° C. Table 3 shows the tensile strength of the bonding pair. The matrix is Al-Zn
The joint efficiency is 87% for the alloy and 78% for AC1A.

[0023]

[Table 2]

[0024]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a micrograph showing a metal structure of a cross section of a joint having a whisker-free portion.

FIG. 2 is a micrograph showing a metal structure of a cross section of a joint obtained by the method of the present invention.

FIG. 3 is a micrograph showing a metal structure of a cross section of a joint obtained at a temperature different from that in FIG. 2;

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-192883 (JP, A) JP-A-62-199276 (JP, A) JP-A-63-30189 (JP, A) JP-A-57-1987 11788 (JP, A) JP-A-58-159987 (JP, A) JP-A-4-9287 (JP, A) JP-A-6-277854 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 20/00-20/26

Claims (3)

(57) [Claims] When joining two whisker-reinforced metal base materials, the surfaces of the materials to be joined are brought into direct contact without any pretreatment to form a matrix of the metal base material in the air. The metal base material is heated to a temperature at which the metal phase can be plastically deformed but does not flow, and a pressure of 10 to 300 MPa is applied from a vertical direction to a contact surface between the two, so that the metal base material and the whisker are substantially not damaged. A joining method characterized by joining. 2. The joining method according to claim 1, wherein the metal phase constituting the matrix is an aluminum alloy. 3. The joining method according to claim 1, wherein the whisker-reinforced metal base material contains 10 to 40% by volume of whiskers.