Cerium-iron alloy and preparation method thereof

Abstract

The invention discloses a cerium-iron alloy and a preparation method thereof. The cerium-iron alloy consists of a cerium element, an iron element and inevitable impurities, the content of the cerium element is greater than 0 wt% and less than or equal to 30 wt%; the cerium-iron alloy is provided with a first cerium-rich phase, a second cerium-rich phase and an iron-rich phase; the content of the first cerium-rich phase is 2-40 wt%, the content of the second cerium-rich phase is 25-55 wt%, and the content of the iron-rich phase is 15-65 wt%; the first cerium-rich phase meets the condition that [Ce] / [Fe] is larger than or equal to 1 and smaller than or equal to 7, the second cerium-rich phase meets the condition that [Ce] / [Fe] is larger than or equal to 0.1 and smaller than or equal to 0.5, and the iron-rich phase meets the condition that [Fe] is larger than or equal to 93 wt%; wherein [Ce] represents the concentration of the cerium element with the unit of wt%, and [Fe] represents the concentration of the iron element with the unit of wt%. The cerium-iron alloy has excellent oxidation resistance.

Description

Technical Field

[0001] The invention relates to a ferrocerium alloy and a preparation method thereof. Background Art

[0002] Ferrocerium alloy can be added to steel as a master alloy to improve the performance of steel. However, ferrocerium alloy has relatively active chemical properties, poor oxidation resistance, and is difficult to store and transport, which restricts its efficient and stable application in steel materials.

[0003] CN103361543A discloses a ferrocerium alloy, wherein the cerium content is 0.1-15wt%, the remainder is Fe and inevitable impurities with a total amount not exceeding 1.0wt%. Metal cerium and pure iron are used as raw materials and smelted in a vacuum induction furnace. The vacuum chamber pressure during smelting is not greater than 100Pa, and the smelting temperature is controlled at 1550-1600°C. After the alloy is completely melted, it is kept in a vacuum state for 4-6 minutes, and then the vacuum is released, and cast into an ingot of a qualified size under the condition of an argon protective atmosphere.

[0004] CN106834889A discloses a ferrocerium alloy, wherein the cerium content is 0-95wt%, the balance is iron and inevitable impurities with a total amount less than 0.5wt%, and the remaining oxygen is ≤0.01wt%, carbon is ≤0.01wt%, phosphorus is ≤0.01wt%, and sulfur is ≤0.005wt%. In an electrolysis device containing a ferrocerium master alloy, cerium oxide is used as an electrolysis raw material in a fluoride molten salt electrolyte system of cerium fluoride and lithium fluoride, and direct current is passed through to electrolyze to obtain the ferrocerium master alloy. The ferrocerium master alloy and iron are used as raw materials to prepare the ferrocerium alloy by a melting method.

[0005] CN108517457A discloses a rare earth lanthanum and cerium alloy, comprising 91-96wt% of iron, 3-8wt% of rare earth lanthanum or cerium, and 0.5-1.5wt% of other impurities. Rare earth lanthanum fluoride or cerium fluoride is placed in a vacuum induction melting furnace, heated to 950-1350°C under vacuum conditions to melt, and when the rare earth lanthanum fluoride or cerium fluoride is in a molten state, excess metal calcium and Fe2O3 or pure iron filings are added, and the temperature is continued to rise to 1350-1600°C in a closed protective atmosphere, and after the iron is melted, it is stirred and kept for 20 to 120 minutes for full reduction; after the thermal reduction reaction is completed, the reaction slag is removed by casting and cooling to obtain the iron lanthanum / iron cerium alloy. The cooling method is to use water cooling at 60-100°C; the closed protective atmosphere is a vacuum induction melting furnace filled with vacuum inert gas protection; the amount of Fe2O3 or pure iron chips is based on the mass ratio of pure iron to required pure lanthanum / cerium of 100%:4-6%; the amount of the required reducing agent metal calcium is calculated according to the stoichiometric calculation of the reduction reaction.

[0006] The above-mentioned ferrocerium alloy has poor oxidation resistance and is difficult to store, which limits its application. Summary of the invention

[0007] One object of the present invention is to provide a ferrocerium alloy having excellent anti-oxidation performance. Another object of the present invention is to provide a method for preparing the ferrocerium alloy.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0009] In one aspect, the present invention provides a ferrocerium alloy, which is composed of cerium, iron and inevitable impurities; the content of the cerium is greater than 0wt% and less than or equal to 30wt%;

[0010] The ferrocerium alloy has a first cerium-rich phase, a second cerium-rich phase and an iron-rich phase; the content of the first cerium-rich phase is 2-40wt%, the content of the second cerium-rich phase is 25-55wt%, and the content of the iron-rich phase is 15-65wt%;

[0011] The first cerium-rich phase satisfies 1≤[Ce] / [Fe]≤7, the second cerium-rich phase satisfies 0.1≤[Ce] / [Fe]≤0.5, and the iron-rich phase satisfies [Fe]≥93wt%; wherein [Ce] represents the concentration of cerium element, in wt%, and [Fe] represents the concentration of iron element, in wt%.

[0012] According to the iron-cerium alloy of the present invention, preferably, the first cerium-rich phase satisfies 50wt%≤[Ce]≤85wt%, 10wt%≤[Fe]≤50wt%; the second cerium-rich phase satisfies 20wt%≤[Ce]≤30wt%, 65wt%≤[Fe]≤85wt%; and the iron-rich phase satisfies [Ce]≤1.8wt%.

[0013] According to the ferrocerium alloy of the present invention, preferably, the first cerium-rich phase satisfies [O]≤13wt%, [C]≤0.5wt%; wherein [O] represents the concentration of oxygen element, and [C] represents the concentration of carbon element.

[0014] According to the iron-cerium alloy of the present invention, preferably, the first cerium-rich phase contains CeFe2 phase, and the second cerium-rich phase contains Ce2Fe 17 Mutually.

[0015] According to the iron-cerium alloy of the present invention, preferably, in any cross section, the second cerium-rich phase surrounds the outer periphery of the first cerium-rich phase, and the iron-rich phase is filled between the second cerium-rich phases.

[0016] According to the iron-cerium alloy of the present invention, preferably, the first cerium-rich phase is embedded in the second cerium-rich phase, and the second cerium-rich phase is distributed in a matrix formed by the iron-rich phase.

[0017] According to the Fe-Ce alloy of the present invention, preferably, most of the second Cerium-rich phase is distributed in the Fe-rich phase in a band-like structure, and the band-like structure is interwoven into a network.

[0018] According to the iron-cerium alloy of the present invention, preferably, the width of the band-like structure at non-intersecting portions is 1-30 μm, and the width at intersecting portions is 10-80 μm.

[0019] On the other hand, the present invention provides a method for preparing the above-mentioned ferrocerium alloy, comprising the following steps:

[0020] (1) Using cerium oxide and iron as electrolytic raw materials, cerium fluoride and lithium fluoride as electrolytes, and adopting a non-consumable cathode method to prepare ferrocerium master alloy;

[0021] (2) Smelting the ferrocerium intermediate alloy and iron to obtain ferrocerium alloy.

[0022] According to the preparation method of the present invention, preferably, in step (1), tungsten or molybdenum is used as a cathode, and a receiver formed of tungsten or molybdenum is arranged below the cathode;

[0023] In step (2), the ferrocerium master alloy and iron are placed in a container formed of alkaline earth metal oxides and / or aluminum oxides and smelted in a smelting furnace.

[0024] The ferrocerium alloy of the present invention has no obvious surface change and no cracking when placed in the air for a long time, and has excellent anti-oxidation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the SEM image of the ferrocerium alloy of Example 1.

[0026] Figure 2 for Figure 1 A partial enlarged view of .

[0027] Figure 3 for Figure 1 A partial enlarged view of .

[0028] Figure 4 This is the SEM image of the ferrocerium alloy of Example 4.

[0029] Figure 5 for Figure 4 A partial enlarged view of .

[0030] Figure 6 for Figure 4 A partial enlarged view of .

[0031] Figure 7 This is a SEM image of the ferrocerium alloy of Comparative Example 1.

[0032] Figure 8 for Figure 7 A partial enlarged view of .

[0033] Fig. 9 for Figure 7 A partial enlarged view of .

[0034] Fig.10 is an XRD diagram; wherein, 10wt.%-CeFe represents the ferrocerium alloy of Example 1, 20wt.%-CeFe represents the ferrocerium alloy of Example 4, and 50wt.%-CeFe represents the ferrocerium alloy of Comparative Example 1.

[0035] Fig.11 This is a photograph of the ferrocerium alloy of Example 1 after being placed in air for 180 days.

[0036] Fig.12 This is a photograph of the ferrocerium alloy of Example 4 after being placed in air for 180 days.

[0037] Fig.13 This is a photograph of the ferrocerium alloy of Comparative Example 1 after being left in air for 180 days. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] <Ferrocerium alloy>

[0040] The ferrocerium alloy of the present invention is composed of cerium elements, iron elements and inevitable impurities. The ferrocerium alloy has a first cerium-rich phase, a second cerium-rich phase and an iron-rich phase. In certain embodiments, the ferrocerium alloy consists of a first cerium-rich phase, a second cerium-rich phase and an iron-rich phase. According to one embodiment of the present invention, on any cross section, the second cerium-rich phase surrounds the periphery of the first cerium-rich phase, and the iron-rich phase is filled between the second cerium-rich phases. Preferably, the second cerium-rich phase is dispersed in the matrix formed by the iron-rich phase. The so-called matrix means that the iron-rich phase is continuously distributed. The cross section can be a cross section at 0.1 to 20 μm from the surface of the ferrocerium alloy, preferably a cross section at 0.5 to 10 μm from the surface of the ferrocerium alloy, and more preferably a cross section at 1 to 5 μm from the surface of the ferrocerium alloy.

[0041] In the ferrocerium alloy of the present invention, the content of cerium is greater than 0wt% and less than or equal to 30wt%. Preferably, the content of cerium is greater than or equal to 5wt%; more preferably, the content of cerium is greater than or equal to 10wt%. In some embodiments, the content of cerium is less than or equal to 25wt%. In other embodiments, the content of cerium is less than or equal to 20wt%.

[0042] The first cerium-rich phase of the present invention satisfies 1≤[Ce] / [Fe]≤7; preferably, satisfies 1.2≤[Ce] / [Fe]≤6.5.

[0043] The first cerium-rich phase may also satisfy 50 wt % ≤ [Ce] ≤ 85 wt %; preferably, 55 wt % ≤ [Ce] ≤ 82 wt %.

[0044] The first cerium-rich phase may also satisfy 10wt%≤[Fe]≤50wt%; preferably, 13wt%≤[Fe]≤45wt%.

[0045] In the above formula, [Ce] represents the concentration of cerium in the first cerium-rich phase, and [Fe] represents the concentration of iron in the first cerium-rich phase, and both units are wt%.

[0046] The first cerium-rich phase may satisfy [T]≤15wt%; preferably, [T]≤13wt%. In some embodiments, [T] may be greater than or equal to 0.5wt%. [T] represents the concentration of elements other than cerium and iron in the first cerium-rich phase.

[0047] The first cerium-rich phase may satisfy [O]≤13 wt %; preferably, [O]≤10 wt %. [O] represents the concentration of oxygen in the first cerium-rich phase.

[0048] The first cerium-rich phase may satisfy [C]≤0.5 wt %; preferably, [C]≤0.2 wt % [C] represents the concentration of carbon in the first cerium-rich phase.

[0049] The first cerium-rich phase may satisfy [S]≤0.5 wt %; preferably, [S]≤0.1 wt % [S] represents the concentration of sulfur in the first cerium-rich phase.

[0050] The first cerium-rich phase may satisfy [Mg]≤0.5 wt %; preferably, [Mg]≤0.1 wt %. [Mg] represents the concentration of magnesium in the first cerium-rich phase.

[0051] The first cerium-rich phase contains a CeFe2 phase. In certain embodiments, the first cerium-rich phase consists of a CeFe2 phase.

[0052] The first cerium-rich phase is randomly dispersed in the second cerium-rich phase. The shape of the first cerium-rich phase is irregular. Taking the irregular strip structure as an example, the width of the first cerium-rich phase is ≤40μm. In some embodiments, the width of the first cerium-rich phase is ≤30μm; in other embodiments, the width of the first cerium-rich phase is ≤20μm; in some further embodiments, the width of the first cerium-rich phase is ≤10μm. In some embodiments, the width of the first cerium-rich phase is ≥0.5μm; in other embodiments, the width of the first cerium-rich phase is ≥1μm; in some further embodiments, the width of the first cerium-rich phase is ≥5μm. This helps to improve the oxidation resistance of ferrocerium alloys.

[0053] The content of the first cerium-rich phase may be 2-40 wt%, preferably 5-30 wt%, and more preferably 8-26 wt%. Controlling the first cerium-rich phase of the present invention within the above content range is helpful to improve the oxidation resistance of the ferrocerium alloy.

[0054] The second cerium-rich phase of the present invention satisfies 0.1≤[Ce] / [Fe]≤0.5; preferably, satisfies 0.2≤[Ce] / [Fe]≤0.4; more preferably, satisfies 0.25≤[Ce] / [Fe]≤0.35.

[0055] The second cerium-rich phase may also satisfy 20wt%≤[Ce]≤30wt%; preferably, 22wt%≤[Ce]≤25wt%.

[0056] The second cerium-rich phase may also satisfy 65wt%≤[Fe]≤85wt%; preferably, 72wt%≤[Fe]≤80wt%.

[0057] In the above formula, [Ce] represents the concentration of cerium in the second cerium-rich phase, and [Fe] represents the concentration of iron in the second cerium-rich phase, and both units are wt%.

[0058] The second cerium-rich phase may satisfy [T]≤5wt%; preferably, [T]≤2wt%. In some embodiments, [T] may be greater than or equal to 0.1wt%. [T] represents the concentration of elements other than cerium and iron in the second cerium-rich phase.

[0059] The second cerium-rich phase may satisfy [O]≤0.5 wt %; preferably, [O]≤0.1 wt % [O] represents the concentration of oxygen in the second cerium-rich phase.

[0060] The second cerium-rich phase may satisfy [C]≤0.5 wt %; preferably, [C]≤0.1 wt % [C] represents the concentration of carbon in the second cerium-rich phase.

[0061] The second cerium-rich phase may satisfy [S]≤0.5 wt %; preferably, [S]≤0.1 wt % [S] represents the concentration of sulfur in the second cerium-rich phase.

[0062] The second cerium-rich phase may satisfy [Mg]≤0.5 wt %; preferably, [Mg]≤0.1 wt % [Mg] represents the concentration of magnesium in the second cerium-rich phase.

[0063] The second cerium-rich phase contains Ce2Fe 17 In certain embodiments, the second cerium-rich phase is composed of Ce2Fe 17 Phase composition.

[0064] Most of the second cerium-rich phase is distributed in the iron-rich phase in a banded structure. A small amount of the second cerium-rich phase is an irregular structure, scattered in the iron-rich phase. The banded structure accounts for more than 90% of the second cerium-rich phase, preferably more than 95%, and more preferably more than 98%. The above proportions are calculated based on the area. The banded structure is interwoven into a network. This helps to improve the oxidation resistance of ferrocerium alloys. In some embodiments, the width of the banded structure at the non-intersecting parts is 1 to 30 μm, preferably 2 to 25 μm, and more preferably 5 to 20 μm. In some embodiments, the width of the banded structure at the intersection is 10 to 80 μm, preferably 15 to 60 μm, and more preferably 35 to 50 μm. This is more helpful to improve the oxidation resistance of ferrocerium alloys.

[0065] In the present invention, the second cerium-rich phase surrounds the periphery of the first cerium-rich phase. In certain embodiments, the first cerium-rich phase is embedded in the second cerium-rich phase. Preferably, more than 90% of the first cerium-rich phase is embedded in the second cerium-rich phase. More preferably, more than 95% of the first cerium-rich phase is embedded in the second cerium-rich phase. Most preferably, 100% of the first cerium-rich phase is embedded in the second cerium-rich phase. The above ratios are calculated based on the area.

[0066] The content of the second cerium-rich phase is 25-55wt%, preferably 30-50wt%. The content of the second cerium-rich phase is greater than that of the first cerium-rich phase. Controlling the second cerium-rich phase within the above content range is helpful to improve the oxidation resistance of the ferrocerium alloy.

[0067] The iron-rich phase of the present invention satisfies [Fe]≥93wt%; preferably, satisfies [Fe]≥95wt%. [Fe] represents the concentration of the iron element in the iron-rich phase.

[0068] The iron-rich phase may satisfy [Ce]≤1.8 wt %, preferably, [Ce]≤1.5 wt %, and more preferably, [Ce]≤1.4 wt %. [Ce] represents the concentration of cerium in the iron-rich phase.

[0069] The iron-rich phase may also satisfy [T]≤5wt%; preferably, [T]≤3.5wt%. In some embodiments, [T] may be greater than or equal to 0.1wt%. In other embodiments, [T] may be greater than or equal to 0.5wt%. [T] represents the concentration of elements other than cerium and iron in the iron-rich phase.

[0070] The iron-rich phase may satisfy [O]≤0.5wt%; preferably, [O]≤0.1wt%. [O] represents the concentration of oxygen in the iron-rich phase.

[0071] The iron-rich phase may satisfy [C]≤0.3wt%; preferably, [C]≤0.05wt%. [C] represents the concentration of carbon in the iron-rich phase.

[0072] The iron-rich phase may satisfy [S]≤0.5wt%; preferably, [S]≤0.1wt%. [S] represents the concentration of sulfur in the iron-rich phase.

[0073] The iron-rich phase may satisfy [Mg]≤0.5wt%; preferably, [Mg]≤0.1wt%; more preferably, [Mg]≤0.05wt%. [Mg] represents the concentration of magnesium in the iron-rich phase.

[0074] The iron-rich phase of the present invention surrounds the periphery of the second cerium-rich phase. The iron-rich phase is distributed in a lamellar shape. The iron-rich phase is filled between the second cerium-rich phases. In certain embodiments, the second cerium-rich phase is distributed in a matrix formed by the iron-rich phase.

[0075] The content of the iron-rich phase is 15-65 wt %, preferably 25-61 wt %. Controlling the content of the iron-rich phase in the present invention within the above range is helpful to improve the oxidation resistance of the ferrocerium alloy.

[0076] <Method for preparing ferrocerium alloy>

[0077] The method for preparing the ferrocerium alloy of the present invention comprises the following steps: (1) preparing the ferrocerium master alloy; and (2) preparing the ferrocerium alloy.

[0078] Steps for preparing ferrocerium master alloy

[0079] The invention uses cerium oxide and iron as electrolytic raw materials, cerium fluoride and lithium fluoride as electrolytes, and adopts a non-consumable cathode method to prepare a ferrocerium intermediate alloy.

[0080] The anode of the present invention may be graphite, for example, a graphite plate.

[0081] The cathode of the present invention may be selected from tungsten or molybdenum. Preferably, the cathode is molybdenum.

[0082] The present invention provides a receiver formed of tungsten or molybdenum below the cathode. Preferably, the receiver is formed of molybdenum. Under the action of electrolysis, the ferrocerium master alloy is enriched on the cathode and falls into the receiver after melting.

[0083] The mass ratio of cerium fluoride to lithium fluoride may be (63-90):(10-37); preferably (70-85):(15-30); more preferably (75-85):(15-25).

[0084] The present invention uses direct current to electrolyze the raw materials cerium oxide and iron. The electrolysis voltage can be 7V to 15V; preferably 8V to 12V; more preferably 8.5V to 11.5V. The electrolysis current can be 3000 to 50000A; preferably 8000 to 30000A; more preferably 10000 to 20000A. The cathode current density can be 5 to 20A / cm 3 ; preferably 7 to 18 A / cm 3 ; More preferably 9 to 15 A / cm 3 The anode current density can be 0.1 to 5 A / cm 3 ; preferably 0.2~4A / cm 3 More preferably, 0.3 to 2 A / cm 3 The electrolysis temperature may be 900 to 1100°C, preferably 930 to 1050°C, and more preferably 950 to 1000°C.

[0085] The cerium content in the ferrocerium master alloy is greater than or equal to 50 wt %, preferably, the cerium content is greater than or equal to 60 wt %, and in some embodiments, the cerium content is 70-90 wt %.

[0086] Steps for preparing ferrocerium alloy

[0087] The invention smelts the ferrocerium intermediate alloy and iron to obtain the ferrocerium alloy.

[0088] Preferably, the ferrocerium master alloy and iron are placed in a container formed of alkaline earth metal oxides and / or aluminum oxides and smelted in a smelting furnace. The alkaline earth metal oxides are selected from one or more of beryllium oxides, magnesium oxides, calcium oxides, strontium oxides, and barium oxides. Preferably, the alkaline earth metal oxides are selected from magnesium oxides and / or calcium oxides. The smelting furnace can be a medium frequency induction furnace.

[0089] The smelting temperature may be 1400-1750°C, preferably 1450-1700°C, and more preferably 1500-1650°C.

[0090] After the ferrocerium master alloy and iron are completely melted, the ferrocerium alloy solution can be obtained by heat preservation. The heat preservation time can be 1 to 10 minutes, preferably 3 to 8 minutes, and more preferably 5 to 6 minutes.

[0091] In certain embodiments, the method further comprises the following steps: casting the ferrocerium alloy solution into a cast iron ingot mold, and then cooling the mold naturally to obtain the ferrocerium alloy.

[0092] Here is the test method:

[0093] The instruments used in the following test methods are as follows: SEM (field emission scanning electron microscope): Zeiss, Sigma500; EDS (energy dispersive spectrometer): Bruker, Xflash6|60.

[0094] SEM test method:

[0095] Sample mounting: Place the ferrocerium alloy sample (size 20mm×20mm×10mm) into the mounting slot of the hot mounting machine. Add mounting material powder into the mounting slot to fill the space other than the space occupied by the ferrocerium alloy sample. Heat the hot mounting machine to 100℃ and keep it warm for 10 minutes to make the mounting material powder completely melt and tightly wrap the ferrocerium alloy sample. After the insulation is completed, take out the sample and cool it to room temperature to obtain the ferrocerium alloy mounting sample.

[0096] Sample grinding and polishing: First, use 200-mesh coarse sandpaper to roughly grind the ferrocerium alloy inlaid sample, and then gradually use finer sandpaper (400 mesh - 800 mesh - 1200 mesh - 1600 mesh - 2000 mesh) to finely grind the sample to gradually improve the surface smoothness of the sample, and finally use polishing cloth to polish the sample until the required surface flatness is achieved.

[0097] Scanning electron microscope test: The flat surface of the ground and polished ferrocerium alloy sample (the distance between the test surface and the original surface of the ferrocerium alloy sample is about 1 to 5 mm) is pasted with conductive glue and observed under a scanning electron microscope. The appropriate working mode and magnification are selected to scan and image the sample.

[0098] Phase content: The sample is first electropolished, and then the grain orientation is analyzed by EBSD scanning. Grains with different orientations are marked with different colors, and their areas are counted to calculate their proportion.

[0099] Element concentration: During the SEM test, EDS analysis can be performed on a specific point to obtain the element content of that point.

[0100] Phase width: obtained from SEM images.

[0101] Examples 1 to 4 and Comparative Example 1

[0102] Cerium oxide, electrolyte and iron are loaded into the electrolytic cell, with a graphite plate as the anode and molybdenum as the cathode. A molybdenum crucible is set under the cathode as a receiver. The electrolyte is cerium fluoride and lithium fluoride with a mass ratio of 83:17. Direct current is passed through cerium oxide, electrolyte and iron for electrolysis. The cerium-iron intermediate alloy is enriched and melted on the cathode and falls into the receiver to obtain a cerium-iron intermediate alloy with a cerium content of 80wt%. The specific electrolysis conditions are: the electrolysis temperature is 950-1000℃, the cathode current density is 10A / cm 2 , electrolysis voltage is 9.5±0.5V, anode current density is 1.1A / cm 2 .

[0103] The ferrocerium master alloy and iron are placed in a magnesium oxide crucible and smelted in a medium frequency induction furnace; after the ferrocerium master alloy and iron are completely melted, they are kept warm for 5 minutes to obtain a ferrocerium alloy solution. The smelting temperature is 1580℃±50℃. The amount of ferrocerium master alloy and iron is determined according to the composition of the ferrocerium alloy. The ferrocerium alloy solution is cast in a cast iron ingot mold and cooled naturally to obtain a ferrocerium alloy.

[0104] The cerium content in the ferrocerium alloy and the contents of the first cerium-rich phase, the second cerium-rich phase and the iron-rich phase are shown in Table 1.

[0105] Table 1

[0106]

[0107] Figure 1-3 is a SEM image of the ferrocerium alloy of Example 1; wherein, Figure 2-3 for Figure 1 A partial enlarged view of Figures 1 to 3 As shown, the second cerium-rich phase surrounds the periphery of the first cerium-rich phase, and more than 90% of the first cerium-rich phase is embedded in the second cerium-rich phase. The first cerium-rich phase is randomly distributed in the second cerium-rich phase, and the shape of the first cerium-rich phase is irregular, wherein the width of the strip-shaped first cerium-rich phase is 1.2 to 15 μm. The iron-rich phase is filled between the second cerium-rich phases, and the second cerium-rich phase is distributed in the matrix formed by the iron-rich phase. Most of the second cerium-rich phase is distributed in the iron-rich phase in a band-like structure, which is interwoven into a network. The width of the band-like structure at the non-intersecting parts is 2 to 20 μm, and the width at the intersecting parts is 20 to 70 μm. A small amount of the second cerium-rich phase is an irregular structure, which is sporadically dispersed in the iron-rich phase. The band-like structure accounts for more than 95% of the second cerium-rich phase. Figure 1 The first cerium-rich phase point C 101 , the second cerium-rich phase point R 101 and iron-rich phase F 101 .exist Figure 2 The first cerium-rich phase point C 102 and C 103 , the second cerium-rich phase point R102 and iron-rich phase F 102 .exist Figure 3 The first cerium-rich phase point C 104 , C 105 and C 106 , the second cerium-rich phase point R 103 and iron-rich phase F 103 .

[0108] Figure 4-6 is a SEM image of the ferrocerium alloy of Example 4; wherein, Figure 5-6 for Figure 4 A partial enlarged view of Figures 4 to 6 As shown, the second cerium-rich phase surrounds the periphery of the first cerium-rich phase, and more than 95% of the first cerium-rich phase is embedded in the second cerium-rich phase. The first cerium-rich phase is randomly distributed in the second cerium-rich phase, and the shape of the first cerium-rich phase is irregular, wherein the width of the strip-shaped first cerium-rich phase is 1.5 to 20 μm. The iron-rich phase is filled between the second cerium-rich phases, and the second cerium-rich phase is distributed in the matrix formed by the iron-rich phase. Most of the second cerium-rich phase is distributed in the iron-rich phase in a band-like structure, which is interwoven into a network. The width of the band-like structure at the non-intersecting parts is 5 to 25 μm, and the width at the intersecting parts is 20 to 80 μm. A small amount of the second cerium-rich phase is an irregular structure, which is sporadically dispersed in the iron-rich phase. The band-like structure accounts for more than 98% of the second cerium-rich phase. Figure 4 The first cerium-rich phase point C 201 , the second cerium-rich phase point R 201 and iron-rich phase F 201 .exist Figure 5 The first cerium-rich phase point C 202 , the second cerium-rich phase point R 202 and iron-rich phase F 202 .exist Figure 6 The first cerium-rich phase point C 203 and C 204 , the second cerium-rich phase point R 203 and iron-rich phase F 203 .

[0109] Figure 7-9 is a SEM image of the ferrocerium alloy of Comparative Example 1; wherein, Figure 8-9 for Figure 7 A partial enlarged view of Figures 7 to 9 As shown, most of the iron-rich phase is embedded in the second cerium-rich phase. The iron-rich phase is irregular in shape and dispersed. The second cerium-rich phase is distributed in the matrix formed by the first cerium-rich phase. The second cerium-rich phase is distributed in an irregular flake shape. Figure 7 The first cerium-rich phase point C 501 , the second cerium-rich phase point R 501 and iron-rich phase F 501 .exist Figure 8The first cerium-rich phase point C 502 and C 503 , the second cerium-rich phase point R 502 and iron-rich phase F 502 .exist Fig. 9 The first cerium-rich phase point C 504 , the second cerium-rich phase point R 503 and iron-rich phase F 503 .

[0110] The element concentration (wt %) of each selected point is shown in Table 2.

[0111] Table 2

[0112]

[0113]

[0114] Note: “—” means the content is too low to be detected.

[0115] Experimental example

[0116] The ferrocerium alloys obtained in Examples 1-4 and Comparative Example 1 were placed in air for 180 days to observe whether cracks appeared on their surfaces. The results are as follows: Figures 11 to 13 And as shown in Table 3.

[0117] Table 3

[0118] Is there any cracking? Example 1 no Example 2 no Example 3 no Example 4 no Comparative Example 1 yes

[0119] After the ferrocerium alloy of the present invention is placed in the air for 180 days, no surface change or cracks occur on the surface, indicating that the ferrocerium alloy has excellent oxidation resistance.

[0120] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A ferrocerium alloy, characterized in that: The ferrocerium alloy is composed of cerium, iron and inevitable impurities; the content of the cerium is greater than 0wt% and less than or equal to 30wt%; The ferrocerium alloy has a first cerium-rich phase, a second cerium-rich phase and an iron-rich phase; the content of the first cerium-rich phase is 2-40wt%, the content of the second cerium-rich phase is 25-55wt%, and the content of the iron-rich phase is 15-65wt%; The first cerium-rich phase satisfies 1≤[Ce] / [Fe]≤7, the second cerium-rich phase satisfies 0.1≤[Ce] / [Fe]≤0.5, and the iron-rich phase satisfies [Fe]≥93wt%; wherein [Ce] represents the concentration of cerium element, in wt%, and [Fe] represents the concentration of iron element, in wt%.

2. The ferrocerium alloy according to claim 1, characterized in that: The first cerium-rich phase satisfies 50wt%≤[Ce]≤85wt%, 10wt%≤[Fe]≤50wt%; the second cerium-rich phase satisfies 20wt%≤[Ce]≤30wt%, 65wt%≤[Fe]≤85wt%; and the iron-rich phase satisfies [Ce]≤1.8wt%.

3. The ferrocerium alloy according to claim 1, characterized in that: The first cerium-rich phase satisfies [O]≤13wt%, [C]≤0.5wt%; wherein [O] represents the concentration of oxygen element, and [C] represents the concentration of carbon element.

4. The ferrocerium alloy according to claim 1, characterized in that: The first cerium-rich phase contains CeFe2 phase, and the second cerium-rich phase contains Ce2Fe 17 Mutually.

5. The ferrocerium alloy according to claim 1, characterized in that: In any cross section, the second cerium-rich phase surrounds the outer periphery of the first cerium-rich phase, and the iron-rich phase is filled between the second cerium-rich phases.

6. The ferrocerium alloy according to claim 5, characterized in that: The first cerium-rich phase is embedded in the second cerium-rich phase, and the second cerium-rich phase is distributed in a matrix formed by the iron-rich phase.

7. The ferrocerium alloy according to claim 5, characterized in that: Most of the second cerium-rich phase is distributed in the iron-rich phase in a band-like structure, and the band-like structure is interwoven into a network.

8. The ferrocerium alloy according to claim 7, characterized in that: The width of the band-like structure at non-intersecting parts is 1 to 30 μm, and the width at intersecting parts is 10 to 80 μm.

9. The method for preparing ferrocerium alloy according to any one of claims 1 to 8, characterized in that: The steps include: (1) Using cerium oxide and iron as electrolytic raw materials, cerium fluoride and lithium fluoride as electrolytes, and adopting a non-consumable cathode method to prepare ferrocerium master alloy; (2) Smelting the ferrocerium intermediate alloy and iron to obtain ferrocerium alloy.

10. The preparation method according to claim 9, characterized in that: In step (1), tungsten or molybdenum is used as a cathode, and a receiver formed of tungsten or molybdenum is arranged below the cathode; In step (2), the ferrocerium master alloy and iron are placed in a container formed of alkaline earth metal oxides and / or aluminum oxides and smelted in a smelting furnace.

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