CN-121976080-A - Preparation method of zirconium boride reinforced molybdenum-base alloy

Abstract

The invention provides a preparation method of a zirconium boride reinforced molybdenum base alloy, which comprises the steps of mixing molybdenum powder and nano zirconium boride powder, and performing ball milling, prepressing and two-stage vacuum hot-pressing sintering to obtain the zirconium boride reinforced molybdenum base alloy. The high-temperature ceramic strengthening phase ZrB 2 ,ZrB 2 introduced into the molybdenum alloy can pin grain boundaries in the sintering process to prevent migration of the grain boundaries, thereby refining grains, improving the density of the grain boundaries, causing fine grain strengthening and reducing the average impurity concentration of the grain boundaries, and simultaneously, the secondary phase can also react with impurity oxygen in a molybdenum matrix to generate zirconia, further reducing the impurity concentration in the alloy and causing dispersion strengthening, and the prepared zirconium boride strengthening molybdenum base alloy has high compression yield strength and good high-temperature stability.

Inventors

• JING KE
• LI ZHIQIANG
• ZHANG YI
• ZHOU MENG
• YANG LU
• CHU CHUNHE
• LIANG HAN
• TIAN BAOHONG

Assignees

• 河南科技大学

Dates

Publication Date

20260505

Application Date

20260302

Claims (9)

1. 1. A preparation method of zirconium boride reinforced molybdenum-base alloy is characterized by comprising the following steps: S1, preparing raw materials: mixing molybdenum powder and nano zirconium boride powder to obtain mixed powder; s2, ball milling: ball milling the mixed powder obtained in the step S1 under a protective atmosphere to obtain ball-milled mixed powder; S3, prepressing: Placing the ball-milled mixed powder obtained in the step S2 into a graphite die, and pre-pressing for 5min under the condition of 25MPa to obtain pre-pressed mixed powder; S4, performing two-stage vacuum hot-pressing sintering on the pre-pressed mixed powder obtained in the S3 to obtain the zirconium boride reinforced molybdenum-base alloy; The two-section type vacuum hot-pressing sintering system comprises the steps of firstly heating from room temperature to 1100 ℃ at the heating rate of 10 ℃ per minute, preserving heat for 1h under the condition that the pressure is 50MPa, heating to 1600 ℃ at the heating rate of 10 ℃ per minute under the constant pressure condition, preserving heat for 0.5h, and naturally cooling to room temperature.
2. 2. The preparation method of the zirconium boride reinforced molybdenum base alloy according to claim 1, wherein the mass fraction of the nano zirconium boride powder in the mixed powder in S1 is 0.5% -1%.
3. 3. The preparation method of the zirconium boride reinforced molybdenum base alloy according to claim 1, wherein the purity of the molybdenum powder in S1 is more than or equal to 99%, the grain size is 1-2 μm, the purity of the nano zirconium boride powder is more than or equal to 99%, and the grain size is 0.2-0.5 μm.
4. 4. The method for producing a zirconium boride reinforced molybdenum-base alloy according to claim 1, wherein the protective atmosphere in S2 is a hydrogen-argon mixture.
5. 5. The method for producing a zirconium boride reinforced molybdenum-base alloy according to claim 4, wherein the volume fraction of hydrogen in the hydrogen-argon mixture is 10%.
6. 6. The preparation method of the zirconium boride reinforced molybdenum base alloy according to claim 1, wherein the ball milling condition in the step S2 is that the ball-material ratio is 13:1, the rotating speed is 300r/min, the ball milling time is 4h, the grinding balls are hard alloy balls made of WC, and the particle size of the hard alloy balls is 5 mm-15 mm.
7. 7. The method for producing a zirconium boride reinforced molybdenum-base alloy according to claim 6, wherein the cemented carbide pellets are formed by mixing cemented carbide pellets having a particle diameter of 5mm, 8mm, 10mm, 12mm, 15mm in this order of equal mass.
8. 8. The method for producing a zirconium boride reinforced molybdenum-base alloy according to claim 1, wherein the two-stage vacuum hot-pressed sintering in S4 has a vacuum degree of <10 -3 MPa.
9. 9. The method for producing a zirconium boride reinforced molybdenum-based alloy according to claim 1, wherein the compressive yield strength of the zirconium boride reinforced molybdenum-based alloy in S4 is >700MPa at room temperature, the vickers hardness at room temperature is >220HV 0.5 , and the vickers hardness at 1000 ℃ is >110HV 0.5 .

Description

Preparation method of zirconium boride reinforced molybdenum-base alloy Technical Field The invention belongs to the technical field of high-temperature structural materials, and particularly relates to a preparation method of a zirconium boride reinforced molybdenum-base alloy. Background Molybdenum and its alloys are widely used in the fields of aerospace, high temperature dies, nuclear power and electronic devices, etc. because of their high melting point (2620 ℃), good high temperature strength, excellent heat and electrical conductivity, and low thermal expansion coefficient. However, the traditional molybdenum alloy still has the defects of insufficient room temperature plasticity and toughness, easy brittle fracture, lower high-temperature recrystallization temperature and limited tissue stability, and the strengthening effect attenuation of the traditional strengthening mode (such as solid solution strengthening and second phase strengthening) at high temperature is obvious. In order to improve the comprehensive performance of the molybdenum alloy, researchers propose to introduce a high-melting-point and high-hardness ceramic phase into a molybdenum matrix for dispersion strengthening. The prior art mainly adopts the following strengthening phases of carbide (such as TiC and ZrC) and oxide (such as La 2O3、Y2O3). The strengthening phase improves the high temperature performance of the molybdenum alloy to a certain extent, but still has the problems of insufficient interfacial bonding, limited thermal stability or larger plastic damage. Zirconium boride (ZrB 2) is taken as an ultra-high temperature ceramic, has an extremely high melting point (> 3200 ℃) and high elastic modulus and high heat conductivity, but the strengthening application of the zirconium boride in molybdenum alloy is rarely systematically researched, and particularly the deep exploration of the optimal addition amount of the zirconium boride in a molybdenum matrix and the cooperative strengthening mechanism of the zirconium boride is lacking. Therefore, the development of the high-performance molybdenum alloy which takes zirconium boride as an ideal strengthening phase, has stable performance and controllable preparation process has important engineering application value. The yttrium ceramic whisker surface modified zirconium niobium boride molybdenum base composite material and the preparation method thereof disclosed in Chinese patent CN 107686931A are characterized in that the zirconium niobium boride molybdenum base composite material after high-temperature sintering is immersed in a surface modification solution containing yttrium ceramic whiskers, and then calcined at 1300-1800 ℃ to obtain the yttrium ceramic whisker surface modified zirconium niobium boride molybdenum base composite material, which has good mechanical properties and corrosion resistance. Chinese patent CN 103981385A discloses a method for preparing a molybdenum-chromium-zirconium boride composite, by introducing chromium into the zirconium boride-molybdenum composite, the sintering temperature can be reduced and the high temperature strength can be improved. However, the brittle phase zirconium boride in the material has high content, the balance of the toughness of the alloy is difficult to ensure, and the problems of complex processing technology, high production cost and the like exist. Disclosure of Invention The technical problem to be solved by the invention is to provide a preparation method of a zirconium boride reinforced molybdenum base alloy, aiming at the defects of the prior art, the method introduces a high-temperature ceramic reinforced phase ZrB 2,ZrB2 into the molybdenum alloy, and can pin grain boundaries in the sintering process to prevent migration of the grain boundaries, thereby refining grains, improving the density of the grain boundaries, causing fine grain reinforcement and reducing the average impurity concentration of the grain boundaries, and simultaneously, a secondary phase can also react with impurity oxygen in a molybdenum matrix to generate zirconium oxide, further reducing the impurity concentration in the alloy and causing dispersion reinforcement. In order to solve the technical problems, the technical scheme adopted by the invention is that the preparation method of the zirconium boride reinforced molybdenum base alloy comprises the following steps: S1, preparing raw materials: mixing molybdenum powder and nano zirconium boride powder to obtain mixed powder; The nano zirconium boride can pin grain boundaries in a molybdenum matrix, promote grain refinement, absorb impurity oxygen in an alloy matrix and improve the strength and high-temperature stability of the molybdenum alloy; s2, ball milling: ball milling the mixed powder obtained in the step S1 under a protective atmosphere to obtain ball-milled mixed powder; S3, prepressing: Placing the ball-milled mixed powder obtained in the step S2 into a graphite die, and pre-pr