JPS629176B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a metal diaphragm with high characteristics, that is, a small density ρ, a high Young's modulus E, and a high loss ΔW/W. This invention relates to metal diaphragms used for diaphragms for players such as turntables, bass absorption panels, etc. Traditionally, the metal materials for acoustic diaphragms, particularly for speaker diaphragms that require high characteristics, are B (boron), Be (beryllium), Ti (titanium),
Duralumin, aluminum (Al), etc. have been used, but each has advantages and disadvantages. Table 1 shows the properties of these metals.

【table】

[Table] Mg is light (small ρ) and has a suitable E.
The speed of sound traveling through the diaphragm v=√ is 51×10 ²
(m/s), which is not bad, but due to the high oxidizability peculiar to the metal, it is difficult to make it thin and use it as a diaphragm in the air.B is ρ. E.
√ However, it has a very high melting point Tm of 2225℃ and is hard, so it is difficult to process it into a thin plate.Until now, it has been used as a cantilever pipe for pickups in stereo players. CVD (Chemical Vapor)
It has been used only as a coating on pipes made of other metal materials using the Deposition method. Be, which has excellent properties, has been put to practical use in some speakers, but Be has a problem in that it is toxic to the human body, and it is difficult to say that it is an optimal metal material for manufacturing and use. Regarding Ti, √ is the same as duralumin, Al, etc., but since ρ is large, when using it as a speaker diaphragm, there is a problem that the reproduction efficiency decreases, and the auditory sense is become poorer.”
There is a drawback. Also, the price is higher than aluminum etc. Duralumin and Al are superior in terms of ease of processing and cost, but their properties, especially E.
is not very high, and √ is also (50~52
×10 ² m/s), there is a problem that the frequency characteristics are somewhat poor. The present invention is a metal material that solves the drawbacks, problems, etc. of the above-mentioned metal materials, and its structure is as follows:
In Al-B system, B is 0.1 to 30 atomic% (at%)
This is a metal diaphragm whose main component is the area of . Furthermore,
This metal diaphragm is characterized in that, in this Al--B alloy, a crystal phase of AlB ₂ is finely and uniformly dispersed in the Al matrix. The effects of the present invention will be explained using the Al--B binary alloy phase diagram shown in FIG. 1 (excerpted from "Metal Data Book (Maruzen)"). Al-B alloy is the first
As can be seen from the phase diagram shown in the figure, as the at% of B increases, the liquidus line of the alloy moves to the high temperature side, and the liquid metal that was on the high temperature side of the liquidus line becomes Al during cooling.
and AlB ₂ are separated and precipitated. In the present invention, different ratios of Al and B (B: 0 to 50 at%) are melted by high-frequency induction heating to give different compositions, and the melted molten metal is cast into a mold to obtain a master alloy. As mentioned above, this mother alloy consists of Al and AlB ₂ , and AlB ₂ is contained in the Al mother crystal.
is precipitated. Then, as a result of measuring the density ρ and Young's modulus E of this master alloy, it was found that the density ρ and the Young's modulus E were 0 to
It has been found that remarkable properties are exhibited in the 30 at% B region. The results are shown in FIG. 2, where the horizontal axis shows at% of B, and the vertical axis shows ρ and E. As shown in Fig. 2, ρ decreases with the concentration of B, and E also decreases with B at 30at.
%, four times that of Al. However, as the concentration of B increases, the toughness and toughness of the entire master alloy decrease, making it brittle.If the concentration exceeds 30 at%, it becomes difficult to dissolve B, and furthermore, it becomes difficult to process and to make it thin for use as a diaphragm. Summer. From measurements of E of master alloys with different compositions, it was found that B increases the Young's modulus E in this way from 0.1 at% or more, as shown in FIG. Therefore, the present invention provides Al
- In the B system, it can be applied to metal diaphragms whose main component is B in the range of 0.1 to 30 at%. Furthermore, in order to improve the properties of the Al-B alloy of the present invention as a diaphragm, the metal structure of the alloy was observed, and the manufacturing and processing methods of the mother alloy were studied. The crystalline phase of AlB ₂ precipitates in the alloy, and we have discovered that fine and homogeneous dispersion of this precipitated phase is effective in reducing the strength of the alloy, reducing variations in Young's modulus, and improving toughness. Therefore, an attempt was made to use liquid super-quenching technology to spray molten metal directly onto a rotating metallic roller, or by spraying and rolling it into a gap between a pair of metallic rollers to form a thin metal strip. ρ of the band.
E was measured, the metal structure was observed, and the Vickers hardness (Hv) was measured. As a result, since the ultra-quenched metal thin body has a high cooling rate of ~10 ⁶ °C/sec, AlB ₂ is finely distributed uniformly within the matrix, the variation in Young's modulus is reduced, and Hv is 10~10 °C/sec. It was found that the amount increased by 30%. The ultra-quenching of the Al--B alloy of the present invention was not limited to the liquid ultra-quenching method, but also other ultra-quenching methods (sputtering method, vapor deposition method, etc.) were found to have an effect on the properties of the obtained thin body. Therefore, the present invention provides Al-B
This is a metal diaphragm made of a (B: 0.1 to 30 at%) alloy in which AlB ₂ crystalline phases are finely and uniformly dispersed in an Al matrix. In addition, the vibration damping capacity ΔW/W≒ of the obtained metal
As a result of measuring (a _o ² - _{a o} ² +1)/a _o ² (a _o is the amplitude intensity of the n-th vibration), it was found that it was more than 50% higher than ΔW/W of Al and duralumin. . This is considered to be due to the high loss and high damping ability of this alloy due to the occurrence of viscous flow at the interface between the parent phase and the second phase in its metallographic structure. Table 1 shows the characteristic values of typical compositions of Al ₉₈ B ₂ and Al ₈₀ B ₂₀ of the present invention. The melting point Tm is
The numbers in parentheses indicate the temperature at which the entire alloy system melts. As can be seen from this table, the Al-B alloy of the present invention has a small ρ and
E is large, and as a result, √ is 60 to 100×10 ²
(m/s), which is between Al, Ti, and B, Be.It is an excellent diaphragm material that has contradictory properties such as high loss and high damping ability, and has excellent processability and cost. It is an extremely suitable material for diaphragms because it can be mass-produced at low cost. Cu, Ti, and Mg are added to the Al-B alloy of the present invention to improve mechanical workability.
There is no problem in adding other third elements such as, and it is also desirable from the point of view of improving characteristics. Next, examples of the present invention will be described. Example 1 Granules with a purity of 99.99% to have a composition ratio of Al ₉₆ B ₄
1.5 g of Al2 and 3.70 g of crystallized granular B (purity 99.9%) are placed in an alumina crucible, the pressure is reduced, the substitution is made with Ar (argon), and high frequency (30 kHz) is applied under an Ar pressure of 68 cmHg.
Al was melted by induction heating to a temperature of about 1400°C, and B was dissolved therein to create a homogeneous Al-B molten metal, which was cast into an iron mold. After cooling to room temperature, it was taken out into the atmosphere and the properties of this master alloy were measured. The density was measured using the Archimedes method, ρ = 2.7 (g/cm ³ ), and the Young's modulus was measured using the flexural vibration method with one end fixed on a sample cut into a strip, E = 1.1×10 ¹² (dyn/cm ² ). I got it. From this value, √ was calculated to be 63×10 ² (m/s). Example 2 As in Example-1, a master alloy adjusted to have a composition ratio of Al ₈₀ B ₂₀ was produced by melting and casting using high-frequency induction heating. Several grams of this master alloy was put into a quartz nozzle with a slit of 0.2 mm width and 10 mm length at one end, and melted at a temperature of 1500°C under an Ar atmosphere. This has a diameter of 300mm and a width of 30mm.
By rapidly adding Ar gas from the other end of a quartz nozzle to the circumference of a copper roller rotating at 1600 rpm and spraying the molten metal, liquid ultra-quenching is performed to obtain a metal ribbon with a width of 10 mm and a thickness of 50 um. Ta. When this thin metal strip is etched and observed under a microscope,
AlB ₂ crystal phases with a size of several μm were uniformly dispersed in the Al matrix. The ρ and E of this metal ribbon were measured, and ρ=2.66 (g/cm ³ ), E=2.5×10 ¹² (dyn/
cm ² ) values were obtained. From this value √=97×10 ²
(m/s).

[Brief explanation of the drawing]

Figure 1 is a phase diagram of the Al-B system, Figure 2 is Al-B
Figure 3 shows the relationship between the B concentration (at%), density ρ, and Young's modulus E in the Al-B system.
%) and Young's modulus E.

Claims (1)

[Claims] 1 Al— consisting of 0.1 to 30 atomic% B and the rest Al—
A metal diaphragm made of B alloy, characterized in that a crystalline phase of AlB ₂ is finely and uniformly dispersed in a matrix of Al.