KR100838734B1 - Fe-based bulk crystals-amorphous composite alloy with high manganese composition - Google Patents

Abstract

An iron-based bulk amorphous alloy having high manganese composition is provided to improve toughness while maintaining glass forming ability by mixing amorphous substance and crystal substance. An iron-based bulk amorphous alloy having high manganese composition contains Mn of 18 ± 0.1 atom percent, Si of 3 ± 0.1 atom percent, Al of 3 ± 0.1 atom percent, Cr of 8 ± 0.1 atom percent, Mo of 0.5 ± 0.1 atom percent, semi-metal 4 to 21 atom percent, balance of Fe and impurity. The semi-metal includes C, B and P. The compositions of C, B and P are 8 ± 0.1 atom percent, 1 ± 0.1 atom percent and 1 ± 0.1 atom percent, respectively. The iron-based bulk amorphous alloy having high manganese composition preferably contains Mn of 16 to 20 atom percent, Si of 1.3 atom percent, Al of 1 to 3.5 atom percent, Cr of 7 to 9 atom percent, Mo of 0.4 to 2 atom percent, and semi-metal 4 to 21 atom percent.

Description

Fe-based bulk Crystals-Amorphous composite alloy with high Manganese composition

1 is a thermal analysis result graph of an amorphous alloy according to an embodiment of the present invention,

2 is a compressive stress strain graph according to the compression test of the amorphous alloy used in the experiment of the present invention,

3 is a TEM microstructure photograph of a crystalline-amorphous alloy showing coexistence of crystals and amorphous phases.

Figure 4 is a diagram showing a process of manufacturing by continuously casting a plate of 2mm thickness using the alloy of the present invention.

The present invention relates to an iron-based crystal-amorphous alloy containing manganese (Mn), and more particularly, in order to solve the problem of brittleness of the alloy system, by mixing the amorphous and crystalline appropriately to maintain the amorphous forming ability, greatly improving the toughness Iron-based crystal-amorphous alloys.

Iron-based bulk amorphous alloys began to be published in the late 2000s, when other amorphous alloys were developed in the mid-1990s, and research results on the development of alloy-based alloys were recently published in the United States and Japan. Although they are announced, most of them have brittle materials and have limitations in plate production.

Since then, a number of iron-based amorphous alloys have been developed and published in the literature in order to develop inexpensive bulk amorphous alloys. However, due to the use of expensive elements, the price of raw materials for alloying elements is increasing, limitations in the manufacturing process, and fragile destruction. Elongation has become a problem and has not been commercialized.

In addition, the conventionally developed bulk amorphous alloys have high alloy cost due to the addition of expensive elements, brittleness due to low elongation compared to high strength, and surface defects and cracks due to thermal shock when manufactured in bulk such as a plate.

The present invention has been invented to solve this problem in view of the above problems, and it contains a large amount of inexpensive manganese to improve amorphous forming ability and at the same time, it is most advantageous for high strength and high toughness and mechanical properties (compressive strength, fracture elongation, etc.). Its purpose is to provide an iron-based crystal-amorphous alloy with an optimal metallurgical composition.

The high manganese iron-based crystal-crystalline alloy composition ratio of the present invention for achieving the above object, Mn: 16-20at%, Si: 1-3at%, Al: 1-33.5at%, Cr: 7-9at%, Mo: 0.4 ~ 2at%, semi-metal element: 4 ~ 21at% The rest is composed of Fe.

And, the preferred composition ratio of the high manganese iron-based crystal-amorphous alloy of the present invention is Mn: 18 ± 0.1 at%, Si: 3 ± 0.1 at%, Al: 3 ± 0.1 at%, Cr: 8 ± 0.1 at%, Mo: 0.5 ± 0.1at%, semimetal element: 4 ~ 21at%, the rest is Fe, the semimetal element is C, B, P, the amount of their use is C: 8 ± 0.1at%, B: 1 ± 0.1at% , P: 1 ± 0.1 at%.

In the composition ratio of the present invention, at% means atomic weight ratio.

In the high manganese iron-based crystal-amorphous alloy of the present invention, manganese (Mn) is intended to exhibit nonmagnetic properties, the amount of which is used is 16 to 20at%, the use of less than or more if the purpose of the present invention It will not be able to exhibit the efficacy of the manganese (Mn) element. Therefore, the amount of Mn used was 16-20 at%. On the other hand, the most preferred amount of Mn is 18 ± 0.1 at%.

Chromium (Cr) and molybdenum (Mo) are used to improve the corrosion resistance, the amount of use is Cr: 7 to 9 at%, Mo: 0.4 to 2 at%, the use of the following or more if the purpose of the present invention Corrosion resistance will not be able to achieve the target value. Therefore, the amount of Cr and Mo used was 7-9 at% and 0.5 ± 0.1 at%, respectively. On the other hand, the most preferable amounts of Cr and Mo are Cr: 8 ± 0.1at% and Mo: 0.5 ± 0.1at%.

Silicon (Si) is used to improve the casting property, the amount of use is Si: 1 to 3 at%, when using less or more, the castability aimed at in the present invention can achieve the target value. There is a problem that is missing or exceeded. Therefore, the usage-amount of Si was 1-3 at%. On the other hand, the most preferable usage of Si is 3 W 0.1at%.

Aluminum (Al), semimetal elements {(carbon (C), boron (B), phosphorus (P)}) is used to improve the amorphous forming ability, the amount of Al used is 1 ~ 3.5at%, semimetal element If the amount of used is 4 ~ 21 at% or less or more than that if the use of the target forming ability in the present invention will not achieve the target value. The most preferred amount of Al is 3 ± 0.1at%, the amount of semimetal element, C, is 8 ± 0.1at%, B is 1 ± 0.1at%, P is 1 ± 0.1at %to be.

Hereinafter, the present invention will be described in detail with reference to Examples.

EXAMPLE

The specimens were prepared in the form of rods with a diameter of 2 mm using vacuum arc melting, and the bulk amorphous specimens were crystallized through XRD (X-ray Diffraction) analysis and DSC (Differential Scanning Calorie meter) analysis. Temperature (Tx), amorphous temperature (Tg), alloy melting temperature (Tm), etc. were measured, and the corrected amorphous transition temperature Trg (= Tg / Tm), which is an indication of amorphous stability, can be used as an index of amorphous stability. The crystal-amorphous temperature difference ΔT (= Tx-Tg) was calculated.

In addition, the diameter of the specimen was processed to 2mm, 3mm height rod-shaped compression specimens through the compression test to measure the mechanical properties of the material (compressive strength, elongation at break, etc.) and the results are shown in Table 1 below.

To summarize the results in Table 1, 18 ± 0.1 at% and 3 ± 0.1 at% Mn and Al were added for the purpose of improving the amorphous forming ability based on the Fe element, maximizing mechanical properties and amorphous alloy properties To do this, 7 to 9 at% and 0.5 to 2 at% of Cr and Mo were added.

Some alloys showed no amorphous properties, and alloys of specific composition showed amorphous properties. Thermal crystallization resulted in clear crystallization peaks due to amorphous formation.

Based on this, crystallization temperature (T _x ), amorphous transition temperature (T _g ), alloy melting temperature (T _m ), etc. were measured, and the corrected amorphous transition temperature, T _rg (= T _g / T _m ) measurement results showed that it has a high amorphous forming ability of 0.48 ~ 0.57.

In addition, the crystal-amorphous temperature difference ΔT (= T _x -T _g ), which is an index of amorphous stability, represented 47 to 131 ° C. In the Cr and Mo change experiments, it was confirmed that the optimum composition was Cr ₈ Mo _0.5 by comparing the amorphous forming ability and the mechanical properties.

In this basic alloy system (Fe _64.5 -Cr ₈ -Mn ₁₈ -Mo _0.5 -Si ₃ -B ₃ ), the amorphous formability and mechanical properties change greatly depending on the semimetal elements (C, B, P). Based on the alloy system, the composition of the alloy system was analyzed by changing the composition of the total sum of semimetal elements to 4 ~ 21at%.

The ease of amorphous formation can be assessed by the critical cooling rate R _c , but it is difficult to formulate or directly measure it theoretically, so it is indirectly evaluated for ease of formation through various other factors.

Representative factors for evaluating the ease of amorphous formation include the subcooled liquid zone ΔT _x (T _x -T _g ), which is represented _{by the difference} between the crystallization temperature T _x and the glass transition temperature T _g , and T _rg (T _g / T _l ) There is a value.

In this experiment, the amorphous forming ability was evaluated through the above factors. In this experiment, the amorphous forming ability (T _rg : 0.58 to 0.65) was shown to be higher than 10%, and ΔT _x was 30 to 110 ° C. It was.

Fe-Cr-Mo-CBP-based alloys, which are known to have excellent amorphous forming ability, vary in the order of atomic radius between constituent atoms in the order of Mo> Cr> Fe> P> B> C and ETM (Early Transition Metal) and Fe In the LTM (Late Transition Metal) element, there is a tremor employment relationship between Fe-Cr and Cr-Mo with negative mixed heat between ETM-LTM, ETM-B and LTM-B pair.

In addition, since Cr / Mo composition ratio affects amorphous forming ability and mechanical properties, experiments were carried out by changing Cr and Mo compositions to 7-9 at% and 0.5-2 at%, respectively, and showed optimum amorphous forming ability (0.48) and mechanical properties. this composition represents the (compressive strength:: 2.29GPa, fracture elongation: 40%) was identified as Cr ₈ Mo _{0 .5.}

 In addition, the experiment was conducted while varying the range of 5at% to 21at% while maintaining the Fe composition of 60at% or more in order to analyze the effect of semimetal elements (C, B, P), which are known to be advantageous for improving amorphous forming ability.

In the alloy system, 3 ± 0.1at% of Si and 3 ± 0.1at% of Al, which is known to improve the amorphous forming ability, were added to improve the fluidity of the alloy during suction casting, and their composition was fixed.

In the alloy system with the total composition of semimetal elements less than 5at%, DSC and XRD analysis showed almost no amorphous properties and the microstructures were mostly crystalline.

On the other hand, when the sum of the semimetal elements is 10%, the amorphous properties (T _rg : 0.53 to 0.65) and the mechanical properties (compressive strength: 1.88 to 2.8 GPa and breaking elongation: 14.8 to 30%) are excellent only in specific compositions. .

Alloy systems containing 21 at% of a semimetal element generally showed excellent amorphous properties (T _rg : 0.58 to 0.63), but mechanical properties (compressive strength: 1.19 to 2.87 GPa and elongation at break: 4.5 to 9%) were relatively high. It was a low level.

The RIBA503 alloy, which has a crystal-amorphous composite structure with the best amorphous forming ability and mechanical properties, was easy to cast stripcast using twin rolls.

In the iron-based amorphous base alloy (FeMn ₁₈ Cr ₈ Mo _0.5 CBPSi ₃ Al ₃ ) used in this experiment, when the sum of the composition of the semimetal elements was less than 5at%, the amorphous property was hardly exhibited. (RIBa503) is a composite structure in which crystal and amorphous phases coexist and shows elastic and inelastic regions in compression test results. Therefore, due to the coexistence of the crystalline phase and the amorphous phase showed excellent amorphous and mechanical properties.

However, when the semi-metallic element was added up to 21at%, most of the tissues were composed of amorphous material, which showed excellent amorphous forming ability, but the mechanical properties were relatively low due to the decrease in elongation due to the absence of crystal phase.

In addition, the present invention has no problem in continuously producing an alloy system having a composition ratio of the present invention in a strip casting process so as to be commercially available in a plate shape of 0.5 to 2 mm in thickness and 100 to 150 mm in width.

The above amorphous alloys (Fe ₅₉ -Cr ₈ -Mn ₁₈ -Mo _0.5 -Si ₃ -B ₃ -C ₈ P ₁ Al ₃ -RIBA503) have amorphous forming ability and mechanical properties (compressive strength: 2.8 GPa, fracture elongation: 30%). As an excellent composite material, it has been able to overcome the weak ductility of most amorphous materials as well as the properties of amorphous high strength, excellent corrosion resistance and excellent elasticity.

In particular, the above-mentioned alloys (RIBA501 ~ 505) can be produced in a plate by using a different purpose depending on the purpose, such as amorphous forming ability, amorphous stabilizing ability, compressive strength, fracture elongation.

Among the alloys, the RIBA 503 alloy, which exhibits crystal-amorphous composite properties, exhibits almost no brittleness, which is typical of amorphous materials, and is also excellent in castability, and is applied to strip casting when applied to a strip casting process. In addition to overcoming brittleness, which is the biggest disadvantage of iron-based alloys reported in the paper, through the amorphous-crystal composite structure, it was possible to manufacture low-cost bulk amorphous alloys with excellent strength and castability.

Claims (5)

delete Mn: 18 ± 0.1at%, Si: 3 ± 0.1at%, Al: 3 ± 0.1at%, Cr: 8 ± 0.1at%, Mo: 0.5 ± 0.1at%, semimetal element: 4 ~ 21at%, rest Has a composition ratio of Fe and indispensable impurities, The semi-metallic elements are C, B, P, and their addition amount is C: 8 ± 0.1 at%, B: 1 ± 0.1 at%, P: 1 ± 0.1 at% high manganese iron-based crystal-amorphous alloy. delete The high-manganese iron-based crystal-amorphous alloy, characterized in that the alloy having a composition ratio of claim 2 is produced in a plate shape of 0.5 ~ 2mm in thickness, 100 ~ 150mm in width by applying to the strip casting process. An alloy system having the composition ratio of claim 2 is manufactured in a rod shape having a diameter of 2 mm through a suction casting process. High manganese iron-based crystal-amorphous alloy.

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