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The present invention relates to a metal material suitable for a member for an electroacoustic
apparatus such as a speaker, a diaphragm such as a microphone, or a cantilever, or a tone arm.
The metal material of this type in the conventional example will be described, for example, for a
speaker diaphragm. Aluminum, titanium, magnesium and their alloys or ceramics as a diaphragm
metal material mainly for high-pitched speakers and middle-pitched speakers. Alternatively, a
composite of ceramic and metal is often used. On the other hand, the diaphragm material is
required to be light jl (small in density) and large in rigidity (large in specific elastic modulus),
but aluminum has a smaller Young's modulus than the density, that is, a small in specific elastic
modulus. Titanium has a very high density, magnesium has a very low density but also a low
Young's modulus, and has the disadvantages that the manufacturing process is complicated and
the cost is high and it is not suitable for mass production. . The present invention is a metal
material having a large specific elasticity that solves the drawbacks of these conventional
examples, and is a metal material composed of an aluminum-lithium-zircon alloy containing
aluminum as a main component, containing 10 wt% or less of lithium and 5 wt% of zircon. % Or
less is desirable. The physical properties of the aluminum-lithium 3 wt% -zircon 0 ° 2 wt% alloy
(sample 1) are shown in Table 1 in comparison with aluminum (sample 2), titanium (sample 3)
and magnesium (sample 4). Table 1 However, E (Young's modulus): X 10 dyn / cm ((density): g /
cm 1 E / p: X 10 dyn cm / g From the above table, the material for acoustic devices of the
present invention is superior to conventional metal materials. It turns out that it has a feature.
Also, as a result of measuring the above-mentioned physical properties by variously changing the
addition ratio of lithium and zircon to aluminum, in the metal material according to the present
invention, lithium is 10-t% or less, optimum value 2-3 vt% (density 6)減 9% decrease, Young's
modulus 12 to 18% increase), zircon 5wt% or less, optimum value 0.18 to 0.20wt% (range where
the low density characteristic of the alloy is not practically alienated) I found it to be. That is, in
the aluminum-lithium alloy, the toughness is low, and the decrease becomes larger as the
addition amount of lithium increases. In the present invention, as described above, the crystal
grains are refined by adding zircon, and the toughness is improved by setting the addition of
lithium in the above range. For example, the results of measurement and comparison of the yield
point and the elongation at yield point of the metal material of the present invention (sample 1)
and aluminum-3 wt% lithium alloy (sample 5) are shown in Table 2.
As clearly shown in Table 2, Table 2, it was found that the metal material according to the
present invention has excellent toughness. The physical properties of the above metal materials
are measured and compared as shown in Table 3. The deterioration of the properties due to the
addition of zircon is practically negligible. E, ρ and E / ρ in Table 3 are the same units as in
Table 1. Furthermore, toughness could be further increased by adding copper and / or
magnesium in addition to aluminum, lithium and zircon. As described in Table 4 and above, the
present invention is a material for electroacoustic equipment consisting of an aluminum-lithiumzircon alloy containing aluminum as a main component, and because it has a large specific elastic
modulus, it is applied to, for example, a speaker diaphragm In this case, the reproduction limit
frequency can be increased, and the reproduction band can be expanded. Patent Applicant Onkyo
Co., Ltd.