Preparation method of molybdenum-rhenium alloy with high-proportion serrated grain boundary structure
Molybdenum rhenium alloy powder was prepared through high-energy ball milling and heat treatment processes, and a high proportion serrated grain boundary structure was constructed, which solved the problem of insufficient mechanical properties of molybdenum rhenium alloy, and achieved performance improvement and life extension.
Patent Information
- Application Number
- CN202510831465.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-20
- Publication Date
- 2025-08-15
Smart Images
Figure CN120485578A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of molybdenum-rhenium alloy microstructure design, and particularly relates to a method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure. Background Art
[0002] Molybdenum-rhenium alloys have the characteristics of high melting point, good corrosion resistance, and excellent comprehensive mechanical properties. They have broad application prospects in fields such as aviation and nuclear energy. The mechanical properties of molybdenum-rhenium alloys are closely related to their grain structure, among which grain boundary cracking is one of its common failure problems. Current research shows that compared with straight grain boundary structures, serrated grain boundary structures have the following advantages: (1) It can increase the surface area and curvature of the grain boundary, hinder dislocation slip, and thus improve the yield strength and hardness of the material.
[0003] (2) The serrated structure can also induce more uniform plastic deformation, reduce stress concentration, delay crack initiation, and improve the fracture toughness of the material.
[0004] (3) The serrated structure can reduce the grain boundary energy, delay the occurrence of dynamic recrystallization at high temperature, and maintain the stability of the material structure.
[0005] (4) The serrated structure can disperse the stress concentration under cyclic load, delay the initiation and expansion of fatigue cracks, and extend the fatigue life of the material.
[0006] Therefore, the serrated structure design of the grain boundary of molybdenum-rhenium alloy is regarded as an important means to improve the comprehensive mechanical properties of molybdenum-rhenium alloy and extend its service life. Summary of the Invention
[0007] The present invention addresses the shortcomings of the prior art by providing a method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure. This method utilizes high-energy ball milling and heat treatment to obtain a molybdenum-rhenium alloy powder with pre-precipitated oxide particles. The oxides then pin the grain boundaries during sintering to create a high-proportion serrated grain boundary structure. This improves the alloy's strength and toughness, extending its service life and addressing the current gap in the preparation of molybdenum-rhenium alloys with a high-proportion serrated grain boundary structure.
[0008] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure, characterized in that a molybdenum-rhenium alloy powder is first prepared by a high-energy ball milling process, and then the molybdenum-rhenium alloy powder is subjected to heat treatment and then solid-phase sintering to obtain a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure. The method specifically comprises the following steps: Step 1: Molybdenum powder, rhenium powder and nano yttrium oxide powder are mixed, and then a molybdenum-rhenium alloy solid solution powder is obtained by a high-energy ball milling process; Step 2: placing the molybdenum-rhenium alloy solid solution powder obtained in step 1 into a vacuum annealing furnace for heat treatment; Step 3: The molybdenum-rhenium alloy solid solution powder heat-treated in step 2 is placed in a graphite mold and pressed to obtain a molybdenum-rhenium alloy blank; Step 4: SPS sintering the molybdenum-rhenium alloy blank obtained in step 3 to obtain a molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure; the serrated grain boundary structure in the molybdenum-rhenium alloy accounts for more than 50%.
[0009] The above-mentioned method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure is characterized in that, in step 1, the molybdenum-rhenium alloy solid solution powder comprises rhenium at a mass fraction of 13% to 15%, yttrium oxide at a mass fraction of 0.9% to 1.1%, and the remainder is molybdenum, and the rhenium and yttrium oxide in the molybdenum-rhenium alloy solid solution powder are solid-dissolved in the molybdenum. In the present invention, by controlling the amount of Y2O3 added to the molybdenum-rhenium alloy, sufficient oxide is added to interact with the grain boundaries, thereby ensuring the formation of a high-proportion serrated grain boundary structure.
[0010] The above-mentioned method for preparing a molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure is characterized in that the purity of the molybdenum powder and rhenium powder in step 1 is not less than 99.97%, and the Fisher particle size is 2.5 ~5.0 The nano-yttrium oxide powder has a particle size of 40 nm to 100 nm, and the mixing is performed at a rotational speed of 80 r / min to 100 r / min for a time of 4 to 6 hours. By controlling the mixing speed and time of the raw materials, the present invention ensures uniform mixing of the molybdenum powder, rhenium powder, and nano-yttrium oxide powder, promotes uniform distribution of the oxides, and effectively ensures uniform and high-proportion distribution of the jagged grain boundaries.
[0011] The above-mentioned method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure is characterized in that the high-energy ball milling process described in step 1 is carried out using a high-energy ball mill, with a ball-to-material ratio of 8 to 10:1, a rotation speed of 260 r / min to 300 r / min, a time of 40 hours to 50 hours, and a rotation-stop cycle of 10 minutes for every 2 hours of ball milling. The high-energy ball milling process is carried out under an Ar and H2 protective atmosphere with a volume ratio of 97:3, and the grinding balls and grinding jar are both made of tungsten carbide. The present invention controls the parameters of the high-energy ball milling process to ensure that sufficient dislocations are introduced during the high-energy ball milling process, forming a high number density of subgrain boundaries, effectively intensifying the interaction between oxides, dislocations, and grain boundaries, and having a positive effect on the formation of high-proportion serrated grain boundaries.
[0012] The above-mentioned method for preparing a molybdenum-rhenium alloy with a high ratio of serrated grain boundary structure is characterized in that the heat treatment in step 2 is carried out at a vacuum degree of 5×10 -3Pa~8×10 -3 The present invention controls the heat treatment under vacuum conditions to minimize the introduction of the impurity element O during the heat treatment process. By controlling the heat treatment temperature and time, the movement and recovery of dislocations are reduced while effectively ensuring the early precipitation of oxides, thereby providing the prerequisite for the interaction between oxides and grain boundaries and the formation of serrated grain boundaries during subsequent sintering.
[0013] The above-mentioned method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure is characterized in that the pressing in step 3 is performed using a hydraulic device, the mold used is made of graphite, and the pressing pressure is 30MPa to 40MPa. By controlling the pressing parameters, the present invention presses the heat-treated molybdenum-rhenium alloy solid solution powder into a molybdenum-rhenium alloy blank, which facilitates subsequent sintering.
[0014] The aforementioned method for preparing a molybdenum-rhenium alloy with a high-proportion serrated grain boundary structure is characterized in that the SPS sintering in step 4 is performed in a spark plasma sintering furnace at a temperature of 1500°C to 1700°C for 20 minutes. By controlling the SPS sintering temperature and time, the present invention ensures sufficient time for the oxides and grain boundaries to interact and form a high-proportion serrated grain boundary structure, while also meeting the alloy's densification requirements.
[0015] Compared with the prior art, the present invention has the following advantages: 1. The present invention obtains a molybdenum-rhenium alloy solid solution powder by mixing molybdenum powder, rhenium powder and nano-yttrium oxide powder and then subjecting the mixture to high-energy ball milling. In combination with heat treatment, oxide particles are precipitated before sintering, providing a prerequisite for the subsequent formation of serrated grain boundaries. In the subsequent sintering process, the pinning effect of the oxides on the grain boundaries is utilized to construct a high-proportion serrated grain boundary structure, thereby improving the comprehensive mechanical properties of the molybdenum-rhenium alloy, including strength and toughness, and extending the service life of the molybdenum-rhenium alloy.
[0016] 2. The present invention controls the size and morphology of the pre-precipitated oxide particles by controlling the high-energy ball milling process and the heat treatment process, thereby hindering the growth of grain boundaries and refining the grains during subsequent sintering, thereby effectively controlling the molybdenum-rhenium grain size and adjusting the properties of the molybdenum-rhenium alloy.
[0017] 3. The preparation process of the present invention is simple and easy to operate. A molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure can be obtained without complicated thermomechanical processing, and is suitable for promotion.
[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is the X-ray diffraction pattern of the molybdenum-rhenium alloy solid solution powder prepared in Example 1 of the present invention.
[0020] Figure 2 This is the IPF (inverse pole figure) image of the heat-treated molybdenum-rhenium alloy solid solution powder prepared in Example 1 of the present invention.
[0021] Figure 3 This is a grain boundary distribution diagram of the molybdenum-rhenium alloy with a high-ratio serrated grain boundary structure prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0022] Example 1 The preparation method of this embodiment first uses a high-energy ball milling process to prepare a molybdenum-rhenium alloy powder, and then obtains a molybdenum-rhenium alloy having a high proportion of serrated grain boundary structure by heat treating the molybdenum-rhenium alloy powder and then solid-phase sintering. The method specifically includes the following steps: Step 1: The purity of the product is not less than 99.97% and the particle size is 2.5 ~5.0 Molybdenum powder, rhenium powder and nano yttrium oxide powder with a particle size of 40nm~100nm are mixed, and the mixing is carried out under an Ar and H2 protective atmosphere with a volume ratio of 97:3. The speed is 100r / min and the time is 6h. Then, the mixture is placed in a high-energy ball mill for high-energy ball milling with a ball-to-material ratio of 8:1, a speed of 260r / min, and a time of 50h. The rotation and stop cycle is 10min for every 2h of ball milling. The high-energy ball milling process is carried out under an Ar and H2 protective atmosphere with a volume ratio of 97:3. The grinding balls and the grinding jar are both made of tungsten carbide to obtain molybdenum-rhenium alloy solid solution powder. The molybdenum-rhenium alloy solid solution powder has a rhenium mass fraction of 14%, a yttrium oxide mass fraction of 1%, and the balance being molybdenum, and the rhenium and yttrium oxide in the molybdenum-rhenium alloy solid solution powder are solid-dissolved in the molybdenum; Step 2: Place the molybdenum-rhenium alloy solid solution powder obtained in step 1 into a vacuum annealing furnace for heat treatment at a vacuum degree of 5×10 -3 Pa, heat treatment temperature is 600℃, heat treatment time is 1h; Step 3: The molybdenum-rhenium alloy solid solution powder heat-treated in step 2 is placed in a graphite mold and pressed by a hydraulic device at a pressure of 30 MPa to obtain a molybdenum-rhenium alloy blank; Step 4: Place the molybdenum-rhenium alloy blank obtained in step 3 into a spark plasma sintering furnace for SPS sintering at a sintering temperature of 1500°C for 20 minutes to obtain a molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure; the serrated grain boundary structure in the molybdenum-rhenium alloy accounts for more than 50%.
[0023] Figure 1The X-ray diffraction pattern of the molybdenum-rhenium alloy solid solution powder prepared in this embodiment is as follows: Figure 1 It can be seen that the diffraction peaks represent the (110), (200), (211) and (220) diffraction peaks of the molybdenum-rhenium alloy solid solution from left to right, indicating the successful preparation of the molybdenum-rhenium alloy solid solution powder.
[0024] Figure 2 This is the IPF (inverse pole figure) image of the heat-treated molybdenum-rhenium alloy solid solution powder prepared in this embodiment, where red represents the molybdenum-rhenium alloy matrix phase and blue represents the yttrium oxide phase. Figure 2 It can be seen that nano-yttrium oxide phase has precipitated in the molybdenum-rhenium alloy solid solution powder after heat treatment. Due to the small size of yttrium oxide, some smaller-sized yttrium oxide phases may not be identified.
[0025] Figure 3 The grain boundary distribution diagram of the molybdenum-rhenium alloy with a high ratio of serrated grain boundary structure prepared in this embodiment is shown in FIG. Figure 3 It can be seen that the molybdenum-rhenium alloy has a high proportion of serrated grain boundary structure, and the average grain size of the alloy is hundreds of nanometers, which is a submicron grain.
[0026] Example 2 The differences between this embodiment and embodiment 1 are as follows: in step 1, the mass fraction of rhenium in the molybdenum-rhenium alloy solid solution powder is 13%, the mass fraction of yttrium oxide is 0.9%, and the balance is molybdenum; the speed of the mixing is 80 r / min and the time is 4 h; the ball-to-material ratio of the high-energy ball milling is 10:1, the speed is 300 r / min, and the time is 40 h; the vacuum degree of the heat treatment in step 2 is 8×10 -3 Pa, the heat treatment temperature is 900℃, and the heat treatment time is 0.5h.
[0027] Example 3 The difference between this embodiment and Example 1 is that the mass fraction of rhenium in the molybdenum-rhenium alloy solid solution powder in step 1 is 15%, the mass fraction of yttrium oxide is 1.1%, and the balance is molybdenum; the pressing pressure in step 3 is 40 MPa; the sintering temperature of the SPS sintering in step 4 is 1700°C, and the time is 20 min.
[0028] Example 4 The difference between this embodiment and embodiment 1 is that the vacuum degree of the heat treatment in step 2 is 5×10 -3 Pa, the heat treatment temperature is 800℃, and the heat treatment time is 0.5h.
[0029] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for preparing a molybdenum-rhenium alloy having a high proportion of serrated grain boundary structure, characterized in that: A molybdenum-rhenium alloy powder is first prepared by a high-energy ball milling process, and then the molybdenum-rhenium alloy powder is heat-treated and then solid-phase sintered to obtain a molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure. The method specifically includes the following steps: Step 1: Molybdenum powder, rhenium powder and nano yttrium oxide powder are mixed, and then a molybdenum-rhenium alloy solid solution powder is obtained by a high-energy ball milling process; Step 2: placing the molybdenum-rhenium alloy solid solution powder obtained in step 1 into a vacuum annealing furnace for heat treatment; Step 3: The molybdenum-rhenium alloy solid solution powder heat-treated in step 2 is placed in a graphite mold and pressed to obtain a molybdenum-rhenium alloy blank; Step 4: SPS sintering the molybdenum-rhenium alloy blank obtained in step 3 to obtain a molybdenum-rhenium alloy with a high proportion of serrated grain boundary structure; the serrated grain boundary structure in the molybdenum-rhenium alloy accounts for more than 50%.
2. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The mass fraction of rhenium in the molybdenum-rhenium alloy solid solution powder in step 1 is 13% to 15%, the mass fraction of yttrium oxide is 0.9% to 1.1%, and the remainder is molybdenum, and the rhenium and yttrium oxide in the molybdenum-rhenium alloy solid solution powder are already dissolved in molybdenum.
3. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The purity of the molybdenum powder and rhenium powder in step 1 is not less than 99.97%, and the Fisher particle size is 2.5 ~5.0 The particle size of the nano yttrium oxide powder is 40nm~100nm, the rotation speed of the mixing is 80r / min~100r / min, and the time is 4h~6h.
4. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The high-energy ball milling process described in step 1 is completed using a high-energy ball mill with a ball-to-material ratio of 8~10:1, a rotation speed of 260r / min~300r / min, a time of 40h~50h, a rotation-stop cycle of 10min for every 2h of ball milling, and the high-energy ball milling process is carried out under an Ar and H2 protective atmosphere with a volume ratio of 97:
3. The grinding balls and grinding jars are both made of tungsten carbide.
5. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The heat treatment in step 2 is carried out under vacuum of 5×10 -3 Pa~8×10 -3 Pa vacuum annealing furnace, the heat treatment temperature is 600℃~900℃, and the heat treatment time is 0.5h~1h.
6. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The pressing in step 3 is performed using a hydraulic device, the mold used is made of graphite, and the pressing pressure is 30MPa~40MPa.
7. The method for preparing a molybdenum-rhenium alloy having a high-ratio serrated grain boundary structure according to claim 1, characterized in that: The SPS sintering in step 4 adopts a spark plasma sintering furnace, the sintering temperature is 1500° C.~1700° C., and the time is 20 minutes.