CN110804710B

CN110804710B - Mo-Tb-Dy alloy material and preparation method thereof

Info

Publication number: CN110804710B
Application number: CN201911300504.4A
Authority: CN
Inventors: 姚茂海; 王选理; 罗天纵; 吕晶; 李�杰; 张晓梅; 杨瑞芳
Original assignee: HUNAN RARE-EARTH METAL RESEARCH INSTITUTE
Current assignee: HUNAN RARE-EARTH METAL RESEARCH INSTITUTE
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2021-04-09
Anticipated expiration: 2039-12-17
Also published as: CN110804710A

Abstract

The invention discloses a Mo-Tb-Dy alloy material, which comprises the following components in parts by weight of 85.4-87.4: 9-10: 3.6-4.6 of Mo, Tb and Dy, wherein the tensile strength Rm of the Mo-Tb-Dy alloy can reach 173.3Mpa at 800 ℃, and the invention also discloses a preparation method of the Mo-Tb-Dy alloy, which comprises the following steps: introducing inert gas for protection, mixing three metal powders of Mo, Tb and Dy, and carrying out ball milling and mixing; carrying out charging and filling on the Mo-RE powder subjected to ball milling and mixing, and carrying out powder preforming by utilizing a cold isostatic pressing process; and (4) sintering the preformed material in vacuum at high temperature. According to the Mo-Tb-Dy alloy material prepared by the invention, due to the addition of Tb and Dy rare earth elements, the high-temperature performance of the Mo-Tb-Dy alloy material is obviously improved, and the tensile strength Rm of the Mo-Tb-Dy alloy material can reach 173.3MPa at 800 ℃.

Description

Mo-Tb-Dy alloy material and preparation method thereof

Technical Field

The invention relates to the field of alloy material preparation, in particular to a Mo-Tb-Dy alloy material and a preparation method thereof.

Background

The molybdenum alloy has good high-temperature performance as a high-temperature alloy, and is widely applied to the industrial fields of machinery, electronics and the like. In the field of nuclear industry, molybdenum alloys are often used as structural materials in nuclear facilities due to their good compatibility with nuclear materials. At room temperature, the molybdenum alloy has poor high and low temperature brittleness transition temperature (DBTT), and is easy to oxidize at high temperature, so that the extension of the application field of the molybdenum alloy is limited.

The existing molybdenum alloys mainly comprise the following components: single crystal molybdenum alloy, molybdenum-rhenium alloy (Mo-Re), molybdenum-titanium-zirconium (MTZ), molybdenum-silicon alloy (Mo-Si), molybdenum rare earth oxide (Mo-REO) and the like, wherein the material properties of each molybdenum alloy are different, and the molybdenum alloy is suitable for different fields. The main problems of the existing molybdenum alloy are as follows: the room temperature brittleness and the high temperature oxidation of the molybdenum alloy. The literature reports that a certain amount of Rare Earth (RE) and Rare Earth Oxide (REO) are added into molybdenum, the recrystallization temperature of the molybdenum can be increased by about 500 ℃, and the rare earth oxide obviously improves the room-temperature tensile strength and the high-temperature performance of the molybdenum. Rare earth oxide is added into molybdenum alloy, and the molybdenum rare earth oxide (Mo-REO) is mainly prepared by a solid-liquid doping mode, a sol-gel doping mode, a sol-spray drying technology and the like.

A method for manufacturing a molybdenum alloy material used for a nuclear fusion device (application number: 201210307083.X) provides a method for preparing a 0.40-0.55 Ti-0.06-0.12 Zr-0.01-0.04C-Mo alloy material by using a powder metallurgy method. The molybdenum alloy material in the patent has poor high-temperature performance, and the rubber tube is adopted for filling and compacting during the cold isostatic pressing process, so that the densification degree of the molybdenum alloy material needs to be improved, and the problem that the size of the molybdenum alloy rod cannot be accurately controlled exists. The application numbers are: 200710034999.1, 20051002080.2, 200610043762.5 and 200610098707.6, the molybdenum rare earth alloy is prepared by different methods such as liquid-liquid doping, solid-liquid doping and solid-solid doping, but no relevant report is found on the preparation technology of molybdenum terbium dysprosium (Mo-Tb-Dy) molybdenum rare earth ternary alloy rods.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the problems in the prior art are solved, the Mo-Tb-Dy alloy material and the preparation method thereof are provided, and the high-temperature performance of the molybdenum alloy material is improved.

The technical scheme adopted by the invention is as follows:

a Mo-Tb-Dy alloy material comprises 85.4-87.4 by weight: 9-10: 3.6 to 4.6 of Mo, Tb and Dy, wherein the tensile strength Rm of the Mo-Tb-Dy alloy is not lower than 173.3Mpa at 800 ℃.

The invention also discloses a preparation method of the Mo-Tb-Dy alloy material, which comprises the following steps:

introducing inert gas for protection, mixing three metal powders of Mo, Tb and Dy, and carrying out ball milling and mixing for 4-12 h, wherein the rotating speed of the ball mill is 200-500 r/min;

under the protection of inert gas, filling the ball-milled and mixed Mo-Tb-Dy powder into a silica gel tube, filling and compacting, fixing and straightening the outside of the silica gel tube, and performing powder material preforming by using a cold isostatic pressing process;

and (3) sintering the preformed material in vacuum, wherein the sintering temperature is 1100-1900 ℃, the sintering time is 8-16 h, and the vacuum degree is less than 133 Pa.

Preferably, the mode of fixing and straightening the outside of the silicone tube is to fix the arc-shaped duct piece outside the silicone tube through an elastic piece.

Preferably, the parameters of the cold isostatic pressing process are that the pressure is more than or equal to 180MPa and less than 200MPa, and the pressure maintaining time is 3-6 min.

Preferably, the preformed material is horizontally placed into a heating device, aluminum oxide powder is coated on the outer side of the preformed material, and vacuum high-temperature sintering is carried out.

Preferably, the Freund granularity of the Mo metal powder is 2.14 μm, the purity is 99.95-99.99%, the average Freund granularity of the Tb metal powder and the Dy metal powder is 2.00 μm, and the purity is 99.95-99.99%.

Compared with the prior art, the invention has the following advantages:

(1) according to the Mo-Tb-Dy alloy material prepared by the invention, due to the addition of Tb and Dy rare earth elements, Mo and the rare earth elements Tb and Dy generate intermetallic compounds, and the intermetallic compounds have the characteristics of high melting point, high stability and the like, and pin crystal boundaries at high temperature, inhibit crystal boundary movement and further obviously improve the high-temperature performance of the alloy. At 800 ℃, the tensile strength Rm of the Mo-Tb-Dy alloy material can reach 173.3MPa, and the Mo-Tb-Dy alloy material has obvious advantages compared with the existing Mo-Tb-Dy alloy material.

(2) The invention adopts a powder metallurgy method to prepare the Mo-Tb-Dy alloy material: after the powder is preformed by cold isostatic pressing, vacuum high-temperature sintering is carried out, so that the densification of the material is facilitated, and the rare earth in the alloy is uniformly distributed. The whole process from mixing to preforming is carried out under the protection of inert gas, so that the impurity content in the alloy is prevented from rising due to the reaction of Tb and Dy rare earth elements and oxygen. Compared with other metallurgy preparation methods, the Mo-Tb-Dy high-temperature alloy is prepared by adopting powder metallurgy, and the technical problems of accurate control of pure rare earth material components, surface protection and coating of pure rare earth materials, forming and control of high-melting-point materials, control of densification processes of difficult-to-process materials and the like are solved.

(3) Fixing the preformed powder by using a silicone tube: compare with the fixed preforming powder of rubber tube, silica gel ductility is better for Mo-Tb-Dy powder is when cold isostatic pressing, and the degree of densification is higher, utilizes the fixed silicone tube of circular arc section of jurisdiction simultaneously, makes the straightness that hangs down of rod higher. The preformed powder is fixed by the silicone tube, so that the size of the prepared rod-shaped section is accurate and controllable, and the popularization and application of the Mo-Tb-Dy high-temperature alloy are facilitated.

(4) When the formed bar is sintered at high temperature, in order to ensure that the formed bar is uniformly heated and prevented from being oxidized at high temperature, the alloy bar is put into aluminum oxide powder for heating. The bar is transversely placed into the heating body, so that the bar is uniformly heated, and stress concentration is avoided.

Drawings

FIG. 1 is a flow chart of a preparation method according to the present invention;

FIG. 2 is a schematic structural view of a silicone tube, an arc tube piece and an elastic piece according to the present invention;

FIG. 3 is a cross-sectional view of FIG. 2;

FIG. 4 is a schematic view of a heating apparatus;

wherein, 1 is the silicone tube, 2 is the circular arc section of jurisdiction, 3 is the elastic component, 4 is the stopcock, 5 is preformed material, 6 is firing equipment, 7 is aluminium oxide, 8 is the preforming, 9 is first last spacer, 10 is second last spacer, 11 is third last spacer, 12 is last top, 13 is the depression bar, 14 is first lower spacer, 15 is last pressure power pole, 16 is second lower spacer, 17 is third lower spacer.

Detailed description of the preferred embodiments

In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.

Example 1

According to the preparation method of the Mo-Tb-Dy alloy material, which is disclosed by the invention, the flow schematic diagram of the method is shown in figure 1, and the Mo-RE high-temperature alloy bar is prepared.

86.57g of Mo metal powder, 9.40g of Tb metal powder and 4.03g of Dy metal powder are weighed, the Fisher particle size of the selected Mo metal powder is 2.14 mu m, the purity is 99.95-99.99%, the average Fisher particle size of the Tb metal powder and the Dy metal powder is 2.00 mu m, and the purity is 99.95-99.99%. Putting the weighed three metal powders into a vacuum glove box, and introducing inert gas into the vacuum glove box. Helium (He) and argon (Ar) may be used as the inert gas, and argon is used in this embodiment. And then mixing the three metal powders, pouring the uniformly mixed metal powder into a ball milling tank, and introducing certain inert gas to protect the materials. The time and the rotation speed of the ball mill are respectively set as 6h and 360 r/min. Separating ball-milled steel balls from ball-milled powder by a mesh screen in a vacuum glove box, directly filling the powder into a silicone tube, sealing two ends of the silicone tube, and performing mechanical filling operation in the powder filling process. As shown in fig. 2-3, the elastic member is a rubber tightening band, and the three arc-shaped tube pieces are fixed to the outer side of the silicone tube by the rubber tightening band, so that the silicone tube is prevented from being bent under a cold isostatic pressure condition, and the silicone tube is prevented from being deformed to break the preformed blank when being subjected to external pressure. The powder is subjected to cold isostatic pressing, namely, the powder in the silicone tube is subjected to pressure preforming through the pressure of oil, and the two ends of the silicone tube need to keep good sealing property so as to prevent the oil from permeating to pollute the powder. And (3) carrying out cold isostatic pressing on the silica gel tube filled with the powder, controlling the pressure to be 180MPa, and keeping the pressure for 3 min. After the powder is pressurized, sectional pressure relief is adopted for pressure relief, the pressure relief is about 50MPa in each stage, and the phenomenon that the bar is broken due to overlarge internal stress of the bar subjected to pre-pressing forming in the continuous unloading process is avoided.

And (3) after the bar is subjected to cold isostatic pressing, taking out the formed bar from the silicone tube, wherein the formed bar needs to be lightly taken to avoid the breakage in the taking-out process. FIG. 4 is a schematic structural diagram of a sintering heating apparatus, wherein a bar is transversely placed into a corundum tube, alumina powder is filled into the corundum tube, the corundum tube is placed into the heating apparatus, and vacuum high-temperature sintering is carried out, wherein the sintering temperature is 1500 ℃, the sintering time is 12h, the vacuum degree is less than 133Pa, and the cooling mode is furnace cooling. The aluminum oxide powder is coated on the bar, so that the bar can be uniformly heated under the high-temperature condition, and the bar can be prevented from being oxidized at high temperature.

And (4) after the alloy bar is sintered at high temperature, annealing the alloy bar to prepare the Mo-Tb-Dy alloy. In the sintering process, the rare earth elements Tb and Dy are easy to burn out, and the actually measured chemical components of the prepared Mo-Tb-Dy alloy are shown in Table 1.

TABLE 1 actually-measured chemical composition (% by mass) of Mo-9.40Tb-4.03Dy alloy

Name of metal	Tb	Dy	Mo
				Mass fraction	9.06	4.59	Balance of

The Mo-9.40Tb-4.03Dy high-temperature alloy bar with high compactness is prepared by adopting a vacuum high-temperature sintering method, and the actually measured density of the Mo-9.40Tb-4.03Dy bar is 9.64g/cm³Near its theoretical density of 9.92g/cm³. Then, the Mo-RE high-temperature alloy bar is subjected to mechanical property test and measurement at room temperature, 200 ℃, 400 ℃, 600 ℃ and 800 ℃ respectivelyThe test result is shown in Table 2, the tensile strength Rm of the Mo-Tb-Dy alloy can reach 173.3Mpa at 800 ℃, and the Mo-Tb-Dy alloy material has obvious advantages compared with the existing Mo-Tb-Dy alloy material.

TABLE 2 mechanical Properties of Mo-Tb-Dy alloys

Example 2

Example 2 differs from example 1 in that the dwell time of the cold isostatic pressing was 3 min.

Comparative example 1

The difference between the comparative example 1 and the example 1 is that the cold isostatic pressing process adopts the process parameters of 100MPa of pressure and 6min of dwell time.

Comparative example 2

Comparative example 2 differs from example 1 in that the cold isostatic pressing process employs a process parameter of 150 MPa.

Comparative example 3

Comparative example 3 differs from example 1 in that the cold isostatic pressing process used a process parameter of 200 MPa.

Comparative example 4

Comparative example 4 is different from example 1 in that the cold isostatic pressing process employs process parameters of 250MPa pressure and 1min dwell time.

The cold isostatic pressing forming conditions of the example 1 and the comparative examples 1 to 4 are shown in table 3, the forming condition of the example 1 is that the surface of the bar is smooth and the product is qualified, and the forming condition of the comparative example 1 is that the powder is not combined and the product is not qualified. Comparative example 2 is powder unbound and product failed. The molding condition of comparative example 3 was that the bar was cracked and the product was not qualified. The molding condition of the comparative example 4 is that the bar is cracked, and the product is unqualified, so that the matched cold isostatic pressing process parameter is 180MPa or more and less than 200MPa, and the pressure maintaining time is 3-6 min when the silicone tube is used.

TABLE 3 Cold isostatic pressing Process parameters for Mo-Tb-Dy alloys

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention. It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A preparation method of a Mo-Tb-Dy alloy material comprises the following steps of: 9-10: 3.6-4.6 of Mo, Tb and Dy, wherein the tensile strength Rm of the Mo-Tb-Dy alloy is not lower than 173.3MPa at 800 ℃, and the Mo-Tb-Dy alloy is characterized by comprising the following steps:

introducing inert gas for protection, mixing three metal powders of Mo, Tb and Dy according to a weight ratio, and carrying out ball milling and mixing, wherein the ball milling time is 4-12 h, and the rotating speed of the ball mill is 200-500 r/min;

performing vacuum sintering on the preformed material, wherein the sintering temperature is 1100-1900 ℃, the sintering time is 8-16 h, and the vacuum degree is less than 133 Pa;

the parameters of the cold isostatic pressing process are that the pressure is more than or equal to 180MPa and less than 200MPa, and the pressure maintaining time is 3-6 min;

and transversely placing the preformed material into heating equipment, coating alumina powder on the outer side of the preformed material, and sintering at high temperature in vacuum.

2. The method of preparing a Mo-Tb-Dy alloy material according to claim 1, wherein: the outer part of the silicone tube is fixedly straightened in a mode that the arc tube piece is fixed to the outer part of the silicone tube through the elastic piece.

3. The method of producing a Mo-Tb-Dy alloy material according to any one of claims 1 to 2, wherein: the Fisher particle size of the Mo metal powder is 2.14 mu m, the purity of the Mo metal powder is 99.95-99.99%, the average Fisher particle size of the Tb metal powder and the Dy metal powder is 2.00 mu m, and the purity of the Tb metal powder and the Dy metal powder is 99.95-99.99%.

4. The method of producing a Mo-Tb-Dy alloy material according to any one of claims 1 to 2, wherein: the inert gas is helium or argon.

5. A Mo-Tb-Dy alloy material produced by the production method according to any one of claims 1 to 4.