JPS61190042A - Spectral reflectivity variable alloy and recording material - Google Patents

Abstract

PURPOSE:To provide a spectral reflectance variable alloy suitable for a recording medium by adding the selected third element at a specific ratio to a binary system of Fe-Zn or Fe-Al and cooling quickly the same from a molten metal. CONSTITUTION:The spectral reflectance variable alloy consists of one of 15-45wt% Fe and Zn and 35-50% Al and <=15% >=1 kinds selected from groups of IA, IIA, IVA, VA, VIA, VIIA, VIII, IB, IIB, IIIB, IVB, VB and rare earths. This alloy has the crystal structure different at the 1st temp. higher than a room temp. and the 2nd temp. lower than said temp. in a solid soln. state. More specifically, the alloy has the crystal structure different from the crystal structure by non-quick cooling at the low temp. when the alloy is quickly cooled from the high temp. The alloy has >=2 kinds of spectral reflectances at the same temp. and can be reversibly changed in the spectral rate when subjected to a heating treatment in a solid phase state. The alloy is used for the recording material by cooling quickly and solidifying the material from a vapor phase or directly from the liquid phase and forming the same into a non-bulk state, etc.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a novel alloy with variable spectral reflectance and a recording material, and in particular to a novel alloy with variable spectral reflectance and a recording material, and in particular, the spectral reflectance of the alloy changes as the crystal structure of the alloy changes due to the application of light and thermal energy. This invention relates to alloys that can be used as media for information recording, display, sensors, etc. that utilize change.

(Background of the Invention) In recent years, as the density of information recording has become higher and digitalization has progressed, various information recording and reproducing methods have been developed.In particular, information recording using laser light energy has been progressing.

The optical disc used for erasing and playing is made of industrial rare metal Na.
80, 1983 (Optical Disks and Materials), it is possible to achieve higher recording density than magnetic disks, and will be a promising method for information recording in the future. this house,
The laser playback device is a compact disc (CD)
It has been put into practical use as

On the other hand, recordable methods can be broadly divided into two types: write-once type and rewritable type. The former allows writing only once and cannot be erased, while the latter allows repeated recording and erasing. In the write-once type recording method, a laser beam is used to destroy or shape the recording portion of the medium to create unevenness, and for reproduction, a change in the amount of light reflected due to the interference of the laser beam at the uneven portion is used for reproduction. For this recording medium, it is generally known that Te or its alloy is used to form irregularities by melting and sublimating Te. This type of medium has some problems such as toxicity. Magneto-optical materials are the mainstream as rewritable recording media. This method uses optical energy to invert and record the local magnetic anisotropy of the medium near the Curie point or the compensation point temperature, and the polarization plane of the polarized incident light at that part is caused by the magnetic Faraday effect and magnetic Kerr effect. Play with the amount of rotation. This method is considered to be the most promising rewritable method, and active research and development is underway with the aim of putting it into practical use in the next few years. However, there is currently no material with a large amount of rotation of the plane of polarization, and even with various measures such as multilayer film formation, there is a big problem that output levels such as S/N and C/N are low.

Other rewritable systems include non-Go and Sn-doped alloys of recording media.

However, this method has a major problem in that the crystallization portion of the amorphous phase is low, and the instability of the phase at room temperature affects the reliability of the disk.

On the other hand, as an alloy utilizing one color tone change, JP-A-57-1
There is an alloy described in Japanese Patent No. 40845. This alloy (12
-15) wt%AQ-(1-5) This is an alloy consisting of wt%Ni-remaining Cu, which utilizes the fact that it reversibly changes from red to golden color at the martensitic transformation temperature. Martensitic transformation is a transformation that inevitably occurs as the temperature decreases, so the color tone obtained when maintained above the martensitic transformation temperature cannot be brought below the martensitic modulation temperature, and conversely, martensitic transformation If a color tone that can be obtained at a temperature below this temperature is raised above the martensitic transformation temperature, it will undergo transformation and change to a different color tone.Therefore, it is impossible to obtain two color tones that occur above and below the martensitic transformation at the same time at the same temperature. Therefore, this principle cannot be applied as a recording material.

[Purpose of the invention]

An object of the present invention is to provide a variable spectral reflectance alloy and a recording material that can maintain partially different spectral reflectances at the same temperature.

[Summary of the invention]

The present invention combines iron, one of the following: 15-45% by weight of zinc and 35-50% by weight of aluminum, and one of the five elements of the periodic table IA, n
A, IVA, VA, VIA, VIA, VI!
[.

The variable spectral reflectance alloy is characterized by comprising at least 15% by weight of at least one third component selected from IB, JIB, mB, IVB, VB groups, and a third component consisting of rare earth elements.

That is, the present invention provides a first temperature higher than room temperature (
An alloy having different crystal structures at a temperature lower than the first temperature (high temperature) and at a temperature lower than the first temperature (low temperature), characterized in that the alloy has a crystal structure that differs from the crystal structure obtained by quenching from the high temperature to the crystal structure obtained by non-quenching at the low temperature. It is an alloy with variable spectral reflectance.

The alloy of the present invention is heated and cooled in the same phase state.

It has at least two types of spectral reflectance at the same temperature.

This allows the spectral reflectance to be changed reversibly.

That is, the alloy according to the present invention has at least 2
It has phases with different crystal structures in two temperature regions, and among them, the spectral reflectance is different between the quenched state of the high temperature phase and the low temperature phase state of the non-quenched standard state. By heating and cooling in the low phase temperature region, the spectral reflectance changes reversibly due to the formation of irregularities due to crystal differences or volume changes.

The principle of reversible change in reflectance of the alloy of the present invention will be explained with reference to FIG. 1. FIG. 0 is a phase diagram of the AB binary alloy.

An AB engineered metal alloy is assumed to be an AB binary alloy having the phase diagram shown in the figure. There are three phase states in the temperature range in the solid state of the alloy with this composition.

In other words, there are b single phase, (b+a) phase, and (a+c) phase.The crystal structure is different for each single phase state of a, b, and Q.Therefore, it is natural for these alone, but also for a mixed phase of these. It is thought that these optical characteristics also change. The spectral reflectance will be explained as a difference in optical properties due to the difference in crystal structure.++ Since the alloy is in the Cr1ch (a + C) phase in the equilibrium state at T1, the spectral reflectance of the alloy is close to that of C.

When this is heated to T4 and rapidly cooled, the b-phase is appropriately cooled to T1, and at T1, the alloy changes to the spectral reflectance of the b-phase. Further, when this appropriately cooled phase is heated and cooled to T2 higher than T1, the b phase changes to an (a + c) phase, and Ti can reversibly change the spectral reflectance to a value close to that of the initial C phase. By repeating such two heating and cooling processes, it is possible to reversibly change the 1-spectral reflectance.

Figure 2 shows the temperature during the heating and quenching process of the alloy.

It is a relationship diagram with recording or erasing.

(Alloy Composition) The alloy of the present invention must have different crystal structures at high and low temperatures, and the rapidly cooled crystal structure must be formed by rapid cooling from a high temperature.
The phase formed by this rapid cooling must be able to change into a crystalline structure at a low temperature by heating at a predetermined temperature.

From these viewpoints, it is preferable to consist of an alloy of iron, 15 to 45% by weight of zinc, 35 to 50% by weight of aluminum, and 15% by weight or less of a third component.

The third component is included because the high-temperature intermetallic compound is stable and the temperature at which the spectral reflectance changes, that is, the solid phase transformation point, can be arbitrarily controlled depending on the application. Specifically, IA, IIA, rVA of the periodic table of elements.

VA, VIA, ■A, ■, I B, UB, II [B, I
VB.

Contains one or more of VB group and rare earth elements.

Group IA elements include lithium, Group IIA elements include magnesium and calcium, Group rVA elements include titanium, zirconium, and hafnium, and Group VA elements include vanadium, niobium, tantalum, and V.
Group IA is chromium, molybdenum, and tungsten, Group ■A is manganese, and Group ■ is cobalt.

Rhodium, iridium, ruthenium, osmium.

Nickel, palladium, platinum, and the UB group are steel and silver.

Gold, and zinc for Group IIB (excluding cases containing zinc).

Cadmium and the UB group include boron, aluminum (except when aluminum is included), and gallium.

Indium (except when indium is essential), IVB group is carbon, silicon, germanium, tin, lead, VB group is phosphorus, antimony, bismuth, rare earths are yttrium, lanthanum, cerium, samarium, gadolinium ,terbium.

Dysprosium and ruthenium are particularly preferred.

(Non-bulk and manufacturing method thereof) In order to obtain reflectance variability, the alloy of the present invention must be able to form a supercooled phase by heating and rapidly cooling the material. In order to create and store information at high speed, it is desirable to use a non-bulk material with a high rapid heating and cooling effect and a small heat capacity. In other words, it is desirable to be a non-bulk material having a volume that allows substantially only a desired area portion to change to a crystal structure different from the standard crystal structure throughout the depth by energy input to a desired minute area. To produce high-density information in a desired micro area, it is desirable to use non-bulk materials such as foils, films, thin wires, or powders with low heat capacity. 0.01-0.2 for information production
It is preferable to have a film thickness of μm. In general, intermetallic compounds are difficult to plastically work.

Therefore, it is effective to directly rapidly cool and solidify the material from the gas phase or liquid phase to form it into a predetermined shape as a method for producing foil, film, thin wire, or powder. These methods include a PVD method (vapor deposition, sputtering method, etc.), a CVD method, and a member having high thermal conductivity that rotates molten tin at high speed. In particular, there are molten metal quenching methods in which molten metal is poured onto the circumferential surface of a metal roll and rapidly solidified, electroplating methods, chemical plating methods, and the like. When using a film or powder material, it is effective to form it directly on the substrate or to apply it and adhere it to the substrate. When applying, a binder that does not cause any reaction even when the powder is heated is preferred. In addition, to prevent oxidation of the material due to heating,
It is also effective to coat the surface of a material, a film formed on a substrate, or a coating layer.

It is preferably formed by quenching a molten metal of foil or thin wire, and preferably has a thickness or diameter of 0.1 m or less.

In particular, a thickness or diameter of 0.05 mm or less is preferred for producing foil or thin wire with a crystal grain size of 0.1 μm or less.

The powder is preferably formed by a Gaia atomization method in which molten metal is atomized together with a gaseous or liquid refrigerant and then poured into water to be rapidly cooled. Its particle size is 0.1 wn
The following are preferable, and ultrafine powder with a particle size of 1 μm or less is particularly preferable.

The film can be formed by vapor deposition, sputtering, CVD medium plating, chemical plating, etc. as described above.

In particular, sputtering is preferable to form a film with a thickness of 0.1 μm or less, and sputtering allows easy control of the target overall composition.

(Structure) The alloy of the present invention has different crystal structures at high and low temperatures, and must have a composition of an undercooled phase that maintains the crystal structure at high temperature at low temperature by rapid cooling from high temperature. At high temperatures, it has an irregular lattice crystal structure, but
The quenching phase is preferably an intermetallic compound having a regular lattice, for example. As the alloy of the present invention can greatly change optical properties, it is preferable to use an alloy that mainly forms this intermetallic compound, and it is particularly preferable that the entire alloy forms an intermetallic compound. 3/2 electron compounds (average outer shell electron concentration e /
An alloy composition in the vicinity of a=3/2) is good.

Further, the alloy of the present invention preferably has an alloy composition having solid phase transformation, particularly eutectoid transformation or enveloping transformation, and the alloy can be obtained with a large difference in spectral reflectance by quenching from high temperature and non-quenching.

The alloy of the present invention preferably has ultrafine crystal grains, and the grain size is particularly preferably 0.1 μm or less.

That is, the crystal grains are preferably smaller than the wavelength of visible light, but may be smaller than the wavelength of semiconductor laser light.

In addition, since the heat capacity of the film formed on the substrate is reduced, the film can be divided into the minimum size of the recording unit by etching or the like.

(Characteristics) The variable spectral reflectance alloy and recording material of the present invention can form at least two types of spectral reflectance in the visible light region at the same temperature. That is, it is necessary that the spectral reflectance of a material having a crystal structure (structure) formed by rapid cooling from a high temperature is different from that of a material having a crystal structure (structure) formed by non-quenching.

Further, the difference in spectral reflectance obtained by quenching and non-quenching is preferably 5% or more, particularly preferably 10% or more. If the difference in spectral reflectance is large, it is easy to visually identify the color, and this has a significant effect in various uses described later.

As a light source for spectrally reflecting, electromagnetic waves other than visible light can be used, and infrared rays, ultraviolet rays, etc. can also be used.

Other properties of the alloy of the present invention include electrical resistivity.

The refractive index of light, the polarization rate of light, and the transmittance of light can also be changed reversibly in the same way as spectral reflectance.

It can be used as a means for recording, reproducing, erasing, displaying various information such as characters, figures, symbols, etc., reproducing sensors, etc., and detecting means.

Since the spectral reflectance is related to the surface roughness of the alloy, it is preferable that at least the intended portion has a mirror surface so as to have 10% or more in the visible light region as described above.

(Applications) The alloy of the present invention has an optical reflectance of electromagnetic waves due to a partial or total change in crystal structure due to heating and rapid cooling.

Physical or electrical properties such as electrical resistivity, refractive index, polarization index, transmittance, etc. can be changed, and changes in these properties can be used for use in elements such as recording, display, and sensors.

As a means of recording information, etc., electrical energy in the form of electricity and current, electromagnetic waves (visible light, radiant heat) are used.

Infrared rays, ultraviolet rays, photographic flash lamp light, electron beams,
Laser beams such as proton beam argon laser, semiconductor laser, etc.
In particular, it is preferable to utilize the change in spectral reflectance caused by irradiation in the recording medium of an optical disk. Optical discs include digital audio discs (DAD or compact discs), video discs, memory discs, and the like, and can be used for these. By using the alloy of the present invention in the recording medium of an optical disc, it can be used in read-only type, additional recording type, and rewritable type disc devices, and is particularly effective in rewritable type disc devices.

An example of the principle of recording and reproduction when the alloy of the present invention is used in an optical disk type recording medium is as follows. First, the recording medium is locally heated and then rapidly cooled to maintain the crystal structure in the high temperature region in the low temperature region to record predetermined information, or the high temperature phase is used as a base to locally heat the recording medium. Information can be reproduced by recording locally in a low-temperature phase during a high-temperature phase, and by irradiating the recorded portion with light and detecting the difference in optical characteristics between the heated portion and the non-heated portion. Furthermore, the recorded information can be erased by heating the portion recorded as information at a temperature lower or higher than the heating temperature at the time of recording. The light is preferably a laser beam, and particularly preferably a short wavelength laser.1 The reflectance between the heated part and the non-heated part of the present invention is 50.
Since it is largest at a wavelength near 0 nm or 800 nm, it is preferable to use a laser beam having such a wavelength for reproduction.The same laser source is used for recording and reproduction,
For erasing, it is preferable to irradiate another laser beam with a lower energy density than that for recording.

Further, a disk using the alloy of the present invention as a recording medium has a great advantage in that it can be visually determined whether information is recorded or not.

As a display, it is possible to partially change the spectral reflectance in visible light, so characters, shapes, symbols, etc. can be recorded without using paint, and these displays can be visually identified. . Furthermore, this information can be erased, and in addition to being used repeatedly by recording and erasing, it is also possible to store it permanently. Examples of its applications include clock faces and accessories.

As a sensor, there is a temperature sensor that utilizes changes in spectral reflectance, especially in visible light. Approximate temperature detection can be made by holding a sensor using the alloy of the present invention, whose temperature at which it changes to a high temperature phase is known in advance, in the temperature range to be measured, and maintaining the appropriate cool phase by cooling it appropriately.

(11 Manufacturing Method) The present invention provides a first temperature higher than room temperature in a solid state and a first temperature higher than room temperature in a solid state.
A part of the surface of the alloy having the chemical composition described above, which has a crystal structure different from that at the second temperature lower than the temperature, is rapidly cooled from the first temperature to form a crystal structure different from the crystal structure at the second temperature. and forming a region having a crystal structure formed by the rapid cooling and forming a different spectral reflectance between the region having the crystal structure formed by the rapid cooling and the region having the crystal structure at the second temperature. It is in the manufacturing method of the alloy.

Furthermore, the present invention provides a method for applying the first temperature to the entire surface of the alloy having the chemical composition described above, which has a different crystal structure at a first temperature higher than room temperature and a second temperature lower than the first temperature in a solid state. 5. Then, a part of the alloy surface is heated to the second temperature to form a region having the crystal structure at the second temperature. and forming different spectral reflectances in the region having the crystal structure formed by the rapid cooling and the region having the crystal structure at the second temperature. be.

The cooling rate from the first temperature is preferably 102° C./second or more, more preferably 103° C./second or more.

[Embodiments of the invention]

Example 1 A Fe-Zn alloy was formed into a foil by a molten metal quenching method, and its color tone change, 2-spectral reflectance, etc. were investigated.

Various alloys containing Fe and 10 to 50 wt% Zn were melted in a high shoulder wave furnace in an argon atmosphere, solidified into a rod shape with a diameter of about 4 m, and cut into pieces with a weight of about 5 to Log to prepare a master alloy for quenching molten metal. .

The molten metal quenching method uses a generally known single-roll type device.1 The master alloy is charged into a quartz nozzle, remelted, and poured onto the outer periphery of a roll (300 mφ) rotating at high speed to a thickness of about 50 mm.
A ribbon-shaped foil with a width of 5ffi and a thickness of μm was produced. Heat this foil in an electric furnace for 2 minutes at each temperature and cool it with water to change the color of the foil! I guessed it. The color of the foils was clearly different between those heat-treated at temperatures above about 650°C and those heat-treated below. Those at room temperature and high temperature were black red, and those at lower temperatures were grayish white. A sufficient difference in spectral reflectance from visible light to near-infrared light was observed between the high-temperature color and the low-temperature color. Furthermore, when a foil that has changed color by rapid cooling from a high temperature range (650°C or higher) is heat treated at a relatively high temperature (350°C or higher) of 650°C or lower, the color changes to the low temperature color. Thereafter, by repeating rapid cooling from a high temperature and heating and cooling at a low temperature, the color of the foil at room temperature changed reversibly. It was also confirmed that by locally heating a part of the foil with a lighter or burner, it is possible to make two colors coexist, and that it can also be used as a display element.

Example 2 An alloy melted and solidified in the same manner as in Example 1 was molded into powder by machining. When this powder was subjected to the same heat treatment as in Example 1, almost the same reversible color change was obtained, and the powder also showed the same phenomenon as the foil.

Example 3 An ingot with a thickness of 5 ms was melted in the same manner as in Example 1 and solidified into a cylindrical shape of approximately 120 mmφ.

A disk with a diameter of Loom was cut out and used as a target for sputter deposition.

A DC-magnetron type sputter deposition method was used, and a hard glass disk with a diameter of about 26 m and a thickness of 1.21 cm was used as the substrate. Substrate temperature 200”C, sputter power 150
Sputter deposition was performed under conditions of W and gas (Ar) partial pressure of 20 mTorr to produce a thin film with a thickness of about 1100 nm. In addition, RF-X Pattani) JA12. O,
or Sin, was deposited to a thickness of about 50 nm.

This alloy thin film was subjected to the same heat treatment as in Example 1. As a result, the color of the thin film at room temperature showed a reversible change similar to that in Example 1 depending on the heating and quenching conditions, and the spectral reflectance from visible light to near-infrared light also changed accordingly. Therefore, it was found that even in such a thin film, there is a reversible change in color tone and spectral reflectance.

Example 4 A sputter-deposited alloy film produced in the same manner as in Example 3 was subjected to recording, reproduction, and erasing using a laser beam. As the laser light, a semiconductor laser (wavelength: 830 nm) or an Ar laser (wavelength: 488 nm) was used. The thin film after the low-temperature heat treatment was irradiated with laser light at a film surface power of 10 to 50 mW and a beam diameter of about 2 to 10 μm. As a result, the irradiated area changed to a color corresponding to when it was heated and rapidly cooled to a high temperature (650° C. or higher). As a result of scanning a line with a laser beam in this way, scanning a low-power laser across the line, and converting the change in reflectance into a DC voltage, an electrical change corresponding to the line was observed. We confirmed that electrical regeneration is possible.

The lines drawn in this way disappeared when the entire film was heated to about 350° C. or when it was irradiated with a laser beam of low power density.

From the above, it was confirmed that this alloy thin film could be recorded, reproduced, and erased by laser light.

Example 5 A Fe-Aα alloy was formed into a foil shape by a molten metal quenching method, and its color tone change, 2-spectral reflectance, etc. were investigated.

Various alloys containing Fe and 30 to 55 w, t% of At are melted in a high-frequency furnace in an argon atmosphere, solidified into rods with a diameter of about 4 cm, and cut into pieces with a weight of about 5 to Log to prepare a matrix for quenching the molten metal. It was made into an alloy.

A commonly known single roll type device was used for the molten metal quenching method. The master alloy is charged into a quartz nozzle, remelted, and poured onto the outer periphery of a roll (300 x φ) rotating at high speed to a thickness of about 50 mm.
A ribbon-shaped foil with a diameter of 5 m and a width of 5 m was produced. The color of the foil was observed by heating it in an electric furnace for 2 minutes at each temperature and cooling it with water.

The color of the foils was clearly different between those heat-treated at temperatures above about 1100°C and those heat-treated below. Those at room temperature and high temperature were black-purple, and those at lower temperatures were grayish-white. A sufficient difference in spectral reflectance from visible light to near-infrared light was observed between the high-temperature color and the low-temperature color. In addition, foil that has been rapidly cooled to change color from a high temperature range (1100°C or higher) can be heated to a relatively high temperature below 1100°C (600°C or higher).
When heat treated at , the color changes to the low temperature color. Thereafter, by repeating rapid cooling from a high temperature and heating and cooling at a low temperature, the color of the foil at room temperature changed reversibly. Furthermore, it was confirmed that when a part of the foil is locally heated with a lighter or burner, the two colors coexist, making it possible to apply it as a single display element.

Example 6 An alloy melted and solidified in the same manner as in Example 5 was molded into powder by machining. When this powder was subjected to the same heat treatment as in Example 5, almost the same reversible color change was obtained, and the powder also showed the same phenomenon as the foil.

Example 7 A 5IIIl thick ingot was melted in the same manner as in Example 5 and solidified into a cylindrical shape of about 120-φ.

A disk with a diameter of 100 cm was cut out and used as a target for sputter deposition.

A DC-magnetron type sputter deposition method was used, and a hard glass disk with a diameter of about 2611 Il and a thickness of 1.2 + m was used as the substrate. Sputter deposition was performed under the conditions of a substrate temperature of 200° C., a sputtering power of 150 W, and a gas (Ar) partial pressure of 20 mTorr to produce a thin film with a thickness of about 1100 nm. In addition, AQ was applied to the film surface by RF sputtering as a protective film.
,0. Or, Sin was deposited to a thickness of about 50 nm.

This alloy thin film was subjected to the same heat treatment as in Example 5. As a result, the color of the thin film at room temperature showed a reversible change similar to that in Example 5 depending on the heating and quenching conditions, and the spectral reflectance from visible light to near-infrared light also changed accordingly. Therefore, it was found that even in such a thin film, there is a reversible change in color tone and spectral reflectance.

Example 8 A sputter-deposited alloy film produced in the same manner as in Example 7 was subjected to recording, reproduction, and erasing using a laser beam. As the laser light, a semiconductor laser (wavelength: 830 nm) or an Ar laser (wavelength: 488 nm) was used. The thin film after the low-temperature heat treatment was irradiated with laser light at a film surface power of 10 to 50 mW and a beam diameter of about 2 to 10 μm. As a result, the irradiated area changed to a color corresponding to when it was heated and rapidly cooled to a high temperature (1100° C. or higher). In this way, we fixedly scanned the laser beam to draw a line, scanned it with a low-power laser across it, and converted the change in reflectance into DC voltage. As a result, we observed a voltage change corresponding to the line. It was confirmed that electrical regeneration is possible.

The lines drawn in this way disappeared when the entire film was heated to about 600° C. or when it was irradiated with a laser beam of low power density. Changes in reflectance are also caused by unevenness due to volume changes.

From the above, it was confirmed that this alloy thin film could be recorded, reproduced, and erased by laser light.

〔Effect of the invention〕

According to the present invention, a novel recording material that utilizes a reversible change in color or reflectance due to crystal-crystal phase transition can be obtained.

[Brief explanation of drawings]

Figure 1 is a binary alloy phase diagram shown to explain the reversible phase change of the correlation between different types of crystals. Figure 2 is an explanation showing the relationship between temperature and recording or erasing during the heating and cooling process of the alloy. It is a diagram.

Claims (1)

[Claims] 1. Iron, 15-45% by weight of zinc and 35% by weight of aluminum
~50% by weight of one of the Periodic Table of Elements I A, IIA, IV
A, VA, VIA, VIIA, VIII, I B, IIB, IIIB,
A variable spectral reflectance alloy comprising at least 15% by weight of one or more selected from IVB, VB groups, and rare earth elements. 2. A part of the alloy surface having a different crystal structure at a first temperature higher than room temperature and a second temperature lower than the first temperature in the solid state is formed by rapid cooling from the first temperature. having a crystal structure different from the crystal structure at the second temperature,
2. The variable spectral reflectance alloy according to claim 1, wherein the other alloy has a crystal structure at the second temperature and has a spectral reflectance different from that of the rapidly cooled crystal structure. 3. The variable light spectral reflectance alloy according to claim 1 or 2, wherein the alloy contains an intermetallic compound. 4. The variable spectral reflectance alloy according to any one of claims 1 to 3, wherein the first temperature is higher than a solid phase transformation point. 5. The difference between the spectral reflectance of the material having a crystal structure formed by the rapid cooling and the spectral reflectance of the material having the crystal structure at the low temperature formed by non-quenching is 5% or more. Claims 1 to 4, which are
The variable spectral reflectance alloy according to any one of the items. 6. Claim 1, characterized in that the spectral reflectance of the alloy is 10% or more in the wavelength range of 400 to 1000 nm.
The variable spectral reflectance alloy according to any one of Items 1 to 5. 7. The variable spectral reflectance alloy according to any one of claims 1 to 6, wherein the alloy is a non-bulk material. 8. Any one of claims 1 to 7, wherein the alloy has a crystal grain size of 0.1 μm or less.
The variable spectral reflectance alloy described in . 9. The variable spectral reflectance alloy according to any one of claims 1 to 8, wherein the alloy is any one of a thin film, foil, strip, powder, and thin wire. 10. Iron, 15-45% by weight of zinc and 35% aluminum
~50% by weight of one of the Periodic Table of Elements I A, IIA, IV
A, VA, VIA, VIIA, VIII, I B, IIB, IIIB,
A recording material comprising an alloy containing one or more and 15% by weight or less of a third component selected from Group IVB, Group VB, and rare earth elements. 11. An alloy having different crystal structures in a solid state at a first temperature higher than room temperature and a second temperature lower than the first temperature, wherein at least a part of the alloy surface is at the first temperature. 11. The recording material according to claim 10, wherein the recording material has an alloy composition that forms a crystal structure different from the crystal structure at the second temperature when quenched from the temperature. 12. The foil or thin wire obtained by pouring the molten metal of the alloy onto the circumferential surface of a rotating roll made of a highly thermally conductive member and solidifying it.Claim 10 or 11 Recording materials listed in Section. 13. The recording material according to claim 10 or 11, characterized in that it is a thin film obtained by depositing the alloy by vapor deposition or sputtering. 14. The recording material according to claim 10 or 11, characterized in that it is made of a powder obtained by spraying the molten metal of the alloy using a liquid or gaseous cooling medium.