JP2010144245A - Zr BASED METAL GLASS ALLOY - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Zr based metal glass alloy in which the formability of an amorphous phase is high, and which has high strength and a low Young's modulus, and can be economically produced as well. <P>SOLUTION: The Zr based metal glass alloy is composed of a raw material containing, by atom%, 50 to 70% zirconium (Zr), 15 to 30% copper (Cu), 5 to 15% aluminum (Al), 2 to 20% iron (Fe) and >0.01 to 0.2% nitrogen (N) as the main components, and comprising one or more kinds selected from hydrogen (H), oxygen (O) and carbon (C) as inevitable impurities. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Zr-based metallic glass alloy having a high ability to form an amorphous phase and having a high strength and a low Young's modulus.

  The metal glass alloy is obtained by rapidly cooling an alloy in a molten state, and means an amorphous metal having no regular arrangement of elements and showing a wide supercooled liquid region like glass. Metallic glass alloys have features such as high coefficient of restitution, high strength, excellent castability, and excellent corrosion resistance, such as golf clubs, mobile phone frames, watch casings, pressure sensors, spring materials, and The range of applications is expanding to gears.

  By the way, as a metallic glass alloy whose application development is progressing, a quaternary metallic glass alloy (Zr-based metallic glass alloy) of Zr—Cu—Al—Ni can be cited. Therefore, in order to further develop the application, there is a demand for a new alloy composition that can produce a metallic glass alloy having physical properties equivalent to or higher than those of the alloy at a lower cost.

As a metallic glass alloy composition satisfying such needs, a quaternary metallic glass alloy of Zr—Cu—Al—Fe has been proposed (for example, see Patent Document 1). According to such an alloy composition, since expensive Ni is replaced by cheap Fe, a Zr-based metallic glass alloy can be provided at a lower cost.
JP-A-9-20968

  However, in the Zr-based alloy composition in which Ni having high amorphous forming ability is replaced with Fe having poor amorphous forming ability, the forming ability of the amorphous phase of the whole alloy (that is, metallic glass forming ability) is lowered. In reality, only fine particles and ribbons with a high cooling efficiency can be obtained as alloy shapes, and bulks with large diameters (for example, diameters exceeding 20 mm), which are important for promoting application development, are directly used. Could not be manufactured.

  The present invention has been made in view of such problems, and the main problems thereof are a Zr-based metal that has a high ability to form an amorphous phase, has high strength, a low Young's modulus, and can be produced economically. It is to provide a glass alloy.

  The invention described in claim 1 is “atomic ratio, 50% to 70% zirconium (Zr), 15% to 30% copper (Cu), 5% to 15% aluminum (Al), 2% or more and 20% or less of iron (Fe) and more than 0.01% and 0.2% or less of nitrogen (N) are the main components, and any of hydrogen (H), oxygen (O), and carbon (C) Or a Zr-based metallic glass alloy made of a raw material containing one or more kinds as inevitable impurities.

  Further, the invention described in claim 2 further limits the Zr-based metallic glass alloy described in claim 1, “50% or more and 70% or less of zirconium (Zr), 15% or more and 30 or more in atomic ratio. % Copper (Cu), 5% to 15% aluminum (Al), 2% to 20% iron (Fe), and more than 0.01% to 0.2% nitrogen (N) The main component is a raw material containing at least one of hydrogen (H), oxygen (O), and carbon (C) as an inevitable impurity, and contains an amorphous phase in a volume ratio of 50% or more. "Zr-based metallic glass alloy".

  In these inventions, in addition to a predetermined amount of metal elements such as Zr, Cu, Al, and Fe as main components, the amorphous forming ability of the alloy composition is added by adding more than 0.01% and 0.2% or less N. Can be improved.

  Although the mechanism by which the amorphous forming ability of the alloy composition is improved by blending a predetermined amount of N in this way is not clear, N having a high affinity with Zr, which is probably the matrix (base material), This is presumably because Zr is bonded to crystallization promoting atoms such as H, O, and C, and these crystallization promoting atoms and Zr are bonded to each other to inhibit crystallization.

  Moreover, since expensive Fe is not used as an alloy composition but inexpensive Ni is used, a Zr-based metallic glass alloy can be provided at a lower cost.

  According to the present invention, by adding a predetermined amount of N as a main component to the quaternary alloy composition of Zr—Cu—Al—Fe, the amorphous phase can be formed with high ability, high strength, and low Young's modulus. A Zr-based metallic glass alloy that can be produced economically can be provided. Further, if such an alloy composition is used, a metallic glass can be formed even when the molten alloy composition is cooled at a relatively low speed, and a large-diameter bulk having a diameter of 20 mm or more and up to about 30 mm can be directly formed. Can be obtained.

  The Zr-based metallic glass alloy according to the present invention has an atomic ratio of 50% to 70% Zr, 15% to 30% Cu, 5% to 15% Al, 2% to 20% Fe. And a raw material containing more than 0.01% and not more than 0.2% N as a main component and any one or more of H, O, and C as inevitable impurities, and then cooled at a critical cooling rate or higher Can be obtained.

  In the Zr-based metallic glass alloy of the present invention, each element group blended at the above ratio has an excellent amorphous forming ability (that is, metallic glass forming ability) and has a supercooled liquid region of 50K or more. It is considered that each element contributes to the following characteristics.

  The supercooled liquid region is defined by the difference between the glass transition point of the alloy obtained by performing differential scanning calorimetry (DSC) at a heating rate of 40 ° C. per minute and the crystallization start temperature. The temperature width ΔTx is expressed by an equation: ΔTx = Tx−Tg (where Tx is a crystallization start temperature and Tg is a glass transition point).

  1) Zr: an element that is a base of the alloy, has an effect of expanding the temperature range ΔTx of the supercooled liquid region, and facilitates formation of an amorphous phase Moreover, it is an element which gives corrosion resistance to the alloy by forming an oxide film in the air.

  2) Cu: has an effect of improving the mechanical properties of the alloy. As described above, the mixing ratio of Cu in the entire alloy of the present invention needs to be 15 atomic% or more and 30 atomic% or less. If the Cu content is less than 15 atomic% or exceeds 30 atomic%, the amorphous forming ability of the alloy is lowered and the strength of the alloy cannot be increased to 1400 MPa or more which is practically required. It is.

  3) Al: Effective in improving the corrosion resistance of the alloy. As described above, the Al content in the entire alloy of the present invention needs to be 5 atomic% or more and 15 atomic% or less. This is because if the Al content is less than 5 atomic% or exceeds 15 atomic%, the amorphous forming ability of the alloy is lowered.

  4) Like Fe: Zr, it has the effect of expanding the temperature range ΔTx of the supercooled liquid region. As described above, the temperature range ΔTx of the supercooled liquid region can be widened by setting the mixing ratio of Fe in the whole alloy in the range of 2 atomic% or more and 20 atomic% or less.

  5) N: There is an effect of improving the amorphous forming ability of the alloy composition. The mechanism by which the amorphous forming ability of the alloy composition is improved is not clear, but N having higher affinity with Zr, which is a matrix (base material), is probably more than the crystallization promoting atoms such as H, O, and C described later. This is presumably because it is bonded to Zr first, and these crystallization promoting atoms and Zr are bonded to each other to prevent crystallization from occurring. In order to exert such an effect, as described above, the mixing ratio of N in the entire alloy of the present invention needs to be more than 0.01 atomic% and not more than 0.2 atomic%, more preferably 0.05 atomic% or more and 0.15 atomic% or less. This will be described in detail later.

  6) H, O, C: Since these elements are “crystallization promoting atoms” that promote crystallization of the alloy, they are preferably not included in the alloy. It is virtually difficult to completely exclude these included crystallization promoting atoms. Therefore, in the alloy of the present invention, these elements are allowed to be included in the alloy as inevitable impurities.

  The alloy composition (mother alloy) composed of the above element composition has a temperature width ΔTx of the supercooled liquid region of 50K or more. As described above, the alloy composition having the temperature range ΔTx of the supercooled liquid region of 50K or more has a wide supercooled liquid region of 50K or more on the low temperature side of the crystallization start temperature Tx when cooled from the molten state. Without passing, after passing the temperature range ΔTx of the supercooled liquid region as the temperature drops, the glass transition point Tg is reached and an amorphous so-called metallic glass alloy is formed. Since the temperature range ΔTx of the supercooled liquid region is as wide as 50K or more, an amorphous solid can be obtained without quenching like a conventionally known amorphous alloy. It becomes possible to mold a block body having a gap.

  When forming a metallic glass alloy using such an alloy composition, the ratio of the amorphous phase to the whole alloy is preferably 50% or more by volume. By doing so, mechanical properties such as tensile strength and elastic properties of the alloy can be dramatically improved.

  When producing the Zr-based metallic glass alloy of the present invention, it is necessary to cool and solidify the melt of the composition (mother alloy) comprising the above elements while maintaining the supercooled liquid state. There are two methods for producing a metallic glass alloy, namely, a rapid cooling method and a slow cooling method, in which the melt cooling rate is different. Specific examples of the rapid cooling method include, for example, a single roll method and a twin roll method in which a ribbon-like product is obtained, a spinning method in a rotating liquid from which a filament-like product is obtained, an atomizing method in which a granular material is obtained, and the like Is mentioned.

  Among these, in the single roll method, first, elemental elemental powders of each component are mixed so as to have the above composition ratio, and then this mixed powder is melted in a melting apparatus such as a crucible in an Ar gas atmosphere to obtain a molten alloy. . Next, the molten metal is sprayed on a rotating metal roll for cooling and rapidly cooled at a critical cooling rate or higher to obtain a ribbon-like metallic glass alloy.

  On the other hand, specific examples of the slow cooling method include a forging method in which molten metal is pressed into a predetermined shape, a rolling method in which molten metal is rolled into a predetermined shape, and a casting method in which molten metal is cast into a predetermined shape. It is done.

  Among these, the casting method is to install the elemental element powder of each component in water-cooled copper hearth so as to have the above composition ratio, melt the metal material by arc discharge or the like in an Ar gas atmosphere, and then mold In this method, the molten metal is cast into the molten metal, and the molten metal is cooled at a critical cooling rate or more to form a metallic glass alloy into a predetermined shape.

  Here, in the metallic glass alloy of the present invention, a predetermined amount of N is an essential main component. For this reason, in both the rapid cooling method and the slow cooling method, a step of blending N into the molten metal is required. Specifically, a predetermined amount of N is mixed with Ar gas that forms an Ar gas atmosphere when the metal material is melted, and the N is brought into contact with the molten metal and blended, or N gas is directly blown into the molten metal. The method of mix | blending etc. is mentioned.

  As described above, the Zr-based metallic glass alloy of the present invention has a high ability to form an amorphous phase because a predetermined amount of N is added as a main component to the Zr—Cu—Al—Fe quaternary alloy composition. A metallic glass alloy having high strength and low Young's modulus can be produced economically. Further, if such an alloy composition is used, a metallic glass can be formed even when the molten alloy composition is cooled at a relatively low speed, and a large-diameter bulk having a diameter of 20 mm or more and up to about 30 mm can be directly formed. Can be obtained.

  Hereinafter, although the experimental result supporting the reason which made predetermined amount N the essential main component in this invention is demonstrated as an Example, this invention is not limited to this example.

1. In order to obtain a metallic glass alloy to be subjected to a relationship experiment between the N compounding ratio in the mother alloy and the metallic glass forming ability and mechanical strength , Zr is 60 atomic%, Cu is 25 atomic%, Al is 10 atomic%, and Fe is A large number of master alloys (see Table 1) in which the compounding ratio of N is changed to 0 to 0.30 atomic% in a metal material adjusted to a composition ratio of 5 atomic% are prepared, and a copper mold inclined casting method is used. This mother alloy was formed into a bulk material having a diameter of 20 mm and a length of 50 mm or more.

  And the metallic glass formation ability and mechanical strength of the obtained bulk material were determined with the following method.

a) Metal glass forming ability: A 20 mm diameter bulk material obtained as described above was cut at a position 30 mm away from the molding start side tip (this part has the fastest cooling rate) at a plane orthogonal to the axial direction. The area of the crystal portion of the cut surface was measured, and the crystal content coefficient k was determined based on the following equation. If the crystal content coefficient k is 10 or more (k ≧ 10), it can be determined that the metal glass forming ability is good.
k = 1 / (area of crystal part / 314)

  b) Breaking brittleness: The bulk material obtained as described above was hit with a free-falling hammer, the strength against impact force and the state of the pattern of the fractured surface were relatively evaluated, and the fracture brittleness was determined as “◎ = resistance to impact force. The machine is classified into four levels: “very high resistance”, “○ = high resistance to impact force”, “△ = slightly resistance to impact force”, and “× = low resistance to impact force”. It was used as an index of the strength of the target.

  Table 1 shows the determination results of the metallic glass forming ability and fracture brittleness in the metallic glass alloys in which the blending ratio of N is changed. In addition, each number in the alloy composition of Table 1 is atomic%.

  As shown in Table 1, when the compounding ratio of N in the metal glass master alloy is less than 0.01 atomic% and more than 0.20 atomic%, the metal glass forming ability becomes inferior, but the mixing ratio of N is 0. It can be seen that those having a concentration of .01 atomic% or more and 0.2 atomic% or less have good metallic glass forming ability. In particular, when the mixing ratio of N in the metallic glass alloy is 0.05 atomic% or more and 0.15 atomic% or less, it can be seen that the metallic glass forming ability is extremely good.

  Further, when the compounding ratio of N in the metallic glass master alloy is 0.01 atomic% or less and 0.25 atomic% or more, the mechanical strength (breaking brittleness) becomes inferior. When the content exceeds 01 atomic% and is 0.2 atomic% or less, it can be seen that the film has good mechanical strength.

  Therefore, from these results, when the compounding ratio of N with respect to the whole master alloy exceeds 0.01 atomic% and is 0.2 atomic% or less, the amorphous forming ability of the alloy composition can be improved. As a result, it was possible to provide a Zr-based metallic glass alloy having excellent mechanical strength.

2. Changes in physical properties depending on the presence or absence of N in the mother alloy The differential scanning calorimetry (DSC) was carried out at a heating rate of 40 ° C. per minute for the bulk material obtained in (1) and for the material containing no N and 0.1 atomic% of N. The results are shown in FIG.

  As shown in FIG. 1, there is no difference in the glass transition point (Tg) in both alloys, but with regard to the crystallization start temperature (Tx), a compound containing N at 0.1 atomic% is an unmixed compound. Compared to this, there is a tendency to slightly shift to the high temperature side. This is considered to suggest that by adding a predetermined amount of N to the master alloy, the temperature range ΔTx of the supercooled liquid region is expanded, and the metal glass forming ability is improved.

It is a graph which shows the differential scanning calorimetry (DSC) result of this invention alloy (N addition) and a comparative example alloy (N no addition).

Claims (2)

In terms of atomic ratio, zirconium (Zr) of 50% to 70%, copper (Cu) of 15% to 30%, aluminum (Al) of 5% to 15%, iron of 2% to 20% (Fe) ), And nitrogen (N) exceeding 0.01% and 0.2% or less as a main component,
A Zr-based metallic glass alloy comprising a raw material containing one or more of hydrogen (H), oxygen (O), and carbon (C) as an inevitable impurity. In terms of atomic ratio, zirconium (Zr) of 50% to 70%, copper (Cu) of 15% to 30%, aluminum (Al) of 5% to 15%, iron of 2% to 20% (Fe) ), And nitrogen (N) exceeding 0.01% and 0.2% or less as a main component,
A raw material containing at least one of hydrogen (H), oxygen (O), and carbon (C) as an inevitable impurity;
A Zr-based metallic glass alloy containing an amorphous phase in a volume ratio of 50% or more.

Images