JP3485720B2 - Manufacturing method of metal matrix composite material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based composite material in which a second-phase particle is dispersed in a first-phase matrix made of a metal or an alloy. The present invention relates to a method of manufacturing by a casting method. [0002] Metal Matrix Composite (MMC)
As a typical example of Composite, there is known a matrix in which reinforcing particles such as ceramics are dispersed as a second phase in a matrix (first phase or base material) made of a metal or an alloy. As the shape of the second phase particles such as reinforcing particles, granular,
Whiskers, fibers and the like are used. In particular, aluminum-based and magnesium-based metal-based composite materials are excellent in light weight, specific strength, specific rigidity, and the like. [0003] Typical production methods for metal matrix composite materials include thermal spraying, casting, sintering, and plating. Among them, particularly, the casting method has already been known for many practical applications since high productivity can be obtained (for example, see the magazine “Metal”, May, 1992, pages 48 to 55). In the casting method, a liquid phase process in which second phase particles such as reinforcing particles are dispersed in a molten metal or alloy to be cast (hereinafter abbreviated as “metal molten metal”) involves uniformly dispersing the second phase particles in a matrix. It is particularly important in making Typical examples of the liquid phase process include an infiltration method and a vortex stirring method.In particular, when particles having low wettability to a molten metal, such as ceramic particles, are used as the second phase particles, in any case, However, special equipment, treatment or adjustment of the alloy composition is required. That is, the infiltration method requires a large-scale facility for applying a high pressure necessary to compensate for low wettability. In addition, in the vortex stirring method, not only long time stirring is required to disperse the particles, but even if stirring is performed for a long time, it is extremely difficult to uniformly disperse the fine particles. For example, as one parameter indicating the wettability of ceramic particles to molten aluminum, there is a balance between gravity (settling force due to volume) acting on ceramic particles and surface tension (lifting force due to surface area). Indeed, the effect of the surface area on the volume increases, making it difficult to transfer fine particles into the molten metal. [0005] As described above, in uniformly dispersing the second phase particles in the matrix, low wettability between the two is a major obstacle. Therefore, conventionally, for the purpose of improving the wettability, a coating treatment is performed on the particle surface, or the temperature of the molten metal is increased, or Mg, Li, Ca, as an alloy element for improving the wettability in the molten metal, Sr, T
The method of adding i, Cu, etc. has been adopted. SUMMARY OF THE INVENTION The present invention relates to a method for producing a second phase particle, which is a particle having a low wettability with a molten metal such as a ceramic particle, or a submicron class particle. Can be evenly dispersed in the matrix,
An object of the present invention is to provide a method for producing a metal matrix composite material by a casting method using vortex stirring. SUMMARY OF THE INVENTION According to the present invention, there is provided, in accordance with the present invention, a method of dispersing second phase particles of Al ₂ O ₃ in a first phase matrix of an Al- ₅ mass % Mg alloy. In the method for producing the metal-based composite material by a casting method using vortex stirring, the above-mentioned second phase particles are added to the above-mentioned molten metal of Al-5 mass % Mg alloy, This is achieved by a method for producing a metal-based composite material, which comprises performing vortex stirring. In the present invention, vibration having a frequency of 20 kHz or more is generally used as the ultrasonic vibration. FIG. 1 shows an ultrasonic vortex stirrer for dispersing and mixing second phase particles in a molten metal by a method of the present invention when a metal matrix composite material is manufactured by a casting method. An example of the configuration will be described. This apparatus includes an ultrasonic vibration system in which an ultrasonic vibrator 1, an ultrasonic horn 2, and an ultrasonic vibration plate 3 are connected in this order. Ultrasonic vibration generated by the ultrasonic vibrator 1 is transmitted from the ultrasonic vibration plate 3 to the molten metal 13 in the crucible 14 via the horn 2. Ultrasonic transducer 1
Is connected to an oscillation section 4 composed of an ultrasonic signal generator and a high-frequency amplifier, and a resonance frequency tracking circuit 5.
The tracking circuit 5 sets the resonance frequency to a predetermined frequency (for example, 20
(kHz). [0009] A predetermined metal or alloy is charged into a crucible 14 and heated by a heating means 15 to form a molten metal 13.
In order to vortex the molten metal 13, the motor 7 is controlled and driven by the motor driver 6, and the rotor 8 attached to the tip of the shaft of the motor 7 is rotated at a constant speed of about 300 to 1000 rpm. The second phase particles 9 such as reinforced particles stored in the hopper 12 are supplied onto the molten metal 13 after passing through a preheating furnace 11 by a carrier gas (for example, nitrogen) from a cylinder 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus shown in FIG.
l or Al-5mass% Mg alloy as matrix
to produce a metal matrix composite material to strengthen particles l ₂ O _3.
The diameter of the Al ₂ O ₃ particles is 50 μm, 3 μm, 0.1 μm.
m. For comparison, a conventional method using only vortex agitation without operating the ultrasonic vibration system shown in FIG. 1 was performed. For the method of the present invention and the comparative method, the process conditions used, the molten metal, and the diameter of the Al ₂ O ₃ reinforcing particles are shown together. [Table 1] First, Al or Al-5 mass% Mg alloy in the form of granules or fragments was charged into the crucible 14 and heated and melted to 1023 K in a nitrogen gas atmosphere by the heating device 15. The vibrating plate 3 was ultrasonically vibrated at a resonance frequency of 20 kHz by an ultrasonic vibration system while vortexing and stirring the stirrer 8 at a constant speed of 300 rpm in the molten metal 13 formed in the crucible 13. However, no ultrasonic vibration was performed in the comparative method. Casting was performed after various stirring times to obtain Examples 1 to 4 according to the present invention and Comparative Examples 5 to 8 according to the conventional method. FIG. 2 shows the relationship between the stirring time and the volume fraction of Al ₂ O ₃ particles for each of the obtained samples. In each case, the filled plot is the data of the sample of the example according to the present invention, and the white plot is the data of the sample of the comparative example according to the conventional method. Here, the relationship between the Al ₂ O ₃ particle volume ratio and the Vickers hardness shown in FIG. 3 was obtained in advance, and the particle volume ratio was converted from the measured value of the Vickers hardness for each sample. First, Al ₂ having a diameter of 50 μm was placed in an Al melt.
Sample 1 of the present invention when O ₃ particles were added
And Sample 5 of Comparative Example are compared. Comparative example sample 5 in which only vortex agitation was performed without applying ultrasonic vibration as before.
In the plot (△ plot in FIG. 2 (the same applies hereinafter)), the volume ratio of Al ₂ O ₃ particles is 0 vol% even after stirring for 1800 seconds, and the Al ₂ O ₃ particles are dispersed in the Al matrix. Not complexed. On the other hand, according to the present invention, sample 1 of the embodiment in which vortex agitation is performed while applying ultrasonic vibration (▲).
In the above, a volume ratio of about 2.5 vol% has already been obtained with a stirring time of 900 seconds, and the volume ratio increases with increasing stirring time, and a volume ratio of about 5 vol% is obtained with a stirring time of 1800 seconds. ing. Next, a 50 μm, 3 μm, or 0.1 μm diameter Al ₂ was added into the Al-5 mass% Mg alloy melt.
In the case where O ₃ particles were added, Sample 2 of the present invention was used.
4 and Comparative Examples 6 to 8 are compared. In the case of a particle diameter of 50 μm, even in the comparative sample 6 (）) in which only vortexing was performed as in the past, the volume ratio of Al ₂ O ₃ particles was about 5 vol% to 7.000 for a stirring time of 300 seconds to 1800 seconds. About 5 vol% is obtained. In contrast, in Example 2 (●) in which vortex stirring was performed while applying ultrasonic vibration according to the present invention, a volume ratio of 9 vol% to 10 vol% was obtained for the same range of stirring time. It can be seen that the volume ratio of Al ₂ O ₃ particles is remarkably improved. When the particle diameters are 3 μm and 0.1 μm,
Comparative samples 7 (□) and 8 in which only vortex stirring was performed
In (◇), no compound was formed by vortex stirring up to 1800 seconds. On the other hand, in the sample samples 3 (お よ び) and 4 (◆) in which vortex stirring was performed while applying ultrasonic vibration according to the present invention, each of the samples was 7 vowels with a stirring time of 1800 seconds.
Al ₂ O ₃ particle volume ratios of about 1% and 2.5 vol% were obtained, and it can be seen that particles having a small diameter, which could not be compounded conventionally, were also compounded. The cross section of each sample was observed under a microscope to examine the composite state of the Al ₂ O ₃ particles. Al-5ma
ss% Mg matrix, Al ₂ O ₃ particle diameter 50 μm,
FIGS. 4A and 4B show the cross-sectional structures when the stirring time is 900 seconds for Comparative Sample 6 and Example Sample 2, respectively. As shown in FIG. 4A, in Comparative Sample 6 in which only vortex stirring was performed as in the conventional case, A
Since the l ₂ O ₃ particles were not completely wetted by the molten metal, a large number of defective portions (black portions that were not spherical) were recognized as cavities. On the other hand, as shown in FIG. 4B, in the sample 2 of the present invention in which the vortex agitation is performed while applying the ultrasonic vibration according to the present invention, the Al ₂ O ₃ particles are completely in the molten metal. Defects are not recognized at all by getting wet,
Al ₂ O ₃ particles are uniformly dispersed in an Al- ₅ mass% Mg matrix. As described above, according to the method of the present invention in which vortex stirring is performed while applying ultrasonic vibration to a molten metal, a shorter time is required as compared with the conventional method using only vortex stirring. By the stirring, a metal matrix composite material in which the second phase particles are uniformly dispersed at a high volume ratio can be manufactured. Further, according to the present invention, even fine particles having a size of several μm or less, which were conventionally extremely difficult to be composited, can be easily composited.
Further, the surface of the second phase particles is completely wetted by the application of the ultrasonic vibration, and no defect occurs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout diagram showing a configuration example of an ultrasonic vortex stirrer for performing a method for producing a metal matrix composite material according to the present invention. FIG. 2 is a diagram showing A in an Al-based or Al-5 mass% Mg alloy-based metal-based composite material manufactured using the apparatus of FIG. 1;
the relationship between l ₂ O ₃ particle volume ratio and stirring time is a graph showing comparison with a comparative example according to the conventional method. FIG. 3 is a graph showing the relationship between Al ₂ O ₃ particle volume ratio and hardness. FIG. 4 shows A and A produced by the present invention and the conventional method.
It is a microscope picture which shows the metal structure of a 1-5 mass% Mg alloy base composite material. [Description of Signs] 1 ... Ultrasonic vibrator 2 ... Ultrasonic horn 3 ... Ultrasonic vibrating plate 4 ... Oscillator 5 ... Resonance frequency tracking circuit 6 ... Motor driver 7 ... Motor 8 ... Rotator 9 ... Second phase particle 10 ... cylinder 11 ... preheating furnace 12 ... hopper 13 ... molten metal 14 ... crucible 15 ... heating means

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshika Tsuruma 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshiki Tsunekawa 2-5-8 Ryumi Minami, Okazaki City, Aichi Prefecture (72 Inventor Naotake Mohri 661-51 Yagoto Ishizaka, Tempaku-ku, Nagoya City, Aichi Prefecture (72) Inventor Masahiro Okumiya 3785, Kuroishi, Shimada, Tenjiro-cho, Tenpaku-ku, Nagoya City, Aichi Prefecture 3391 (72) Inventor Yuko Tanada, Nagoya City, Aichi Prefecture 2-12 Hisakata, Tenpaku-ku Toyota Technological Institute (56) References JP-A-2-197536 (JP, A) JP-A-5-65564 (JP, A) JP 3-46533 (JP, B2) Kohei 6-13721 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 1/10 B22D 19/00 B22D 19/14

Claims (1)

(57) [Claim 1] Vortex stirring of a metal matrix composite material in which second phase particles made of Al ₂ O ₃ are dispersed in a first phase matrix made of an Al- ₅ mass % Mg alloy. Wherein the second phase particles are added to a molten metal of the Al-5 mass % Mg alloy, and the vortex stirring is performed while applying ultrasonic vibration to the molten metal. A method for producing a metal matrix composite material.