阅读说明：本技术 一种第二相强化高熵粘结剂硬质合金及其制备方法 (Second-phase reinforced high-entropy binder hard alloy and preparation method thereof ) 是由 王鑫铭 陈夏琪 张卫兵 刘向中 尹付成 文涛 刘斌 于 2021-07-08 设计创作，主要内容包括：本发明公开了一种第二相强化高熵粘结剂硬质合金及其制备方法,其特征为所述高熵合金粘结相成分以原子比例计,包括以下成分：其中Fe:Co:Ni:Al:Ti(Nb、Ta等)＝1:1:1:x:y(x<1,y<1)。将金属粉末混合在球磨机中进行机械合金化,得到高熵合金粉末,高熵粘结相的质量百分比占总体系的10wt.％～30wt.％。将原料置于行星球磨机中进行高能球磨,形成高熵合金粉末后,放入球磨机中低速混合高熵合金粉末与硬质相WC粉末,得到混料。经放电等离子烧结,得到硬质合金烧结体。所述烧结工艺采用压力为20～60Mpa,控制烧结温度在1000～1500℃,保温时间为4～10min。本发明高熵合金粘结相中由第二相γ’相强化,所得到的硬质合金致密度达到96～99.8％,硬度达到1100～2300HV-(30),断裂韧性达到9～20MNm～(-3/2),其力学性能较工业常用Co基粘结相硬质合金要好,在高性能硬质合金应用领域,提供了更加优质的材料选择。(The invention discloses a second-phase reinforced high-entropy binder hard alloy and a preparation method thereof, and is characterized in that the components of the high-entropy binder phase comprise the following components in atomic proportion: wherein Fe, Co, Ni, Al, Ti (Nb, Ta, etc.) -1: 1:1: x, y (x)<1,y<1). And mixing the metal powder in a ball mill for mechanical alloying to obtain the high-entropy alloy powder, wherein the mass percent of the high-entropy binding phase accounts for 10-30 wt% of the total system. Placing the raw materials in a planetary ball mill for high-energy ball milling to form high-entropy alloy powder, and then placing the high-entropy alloy powder and hard-phase WC powder in the ball mill for low-speed mixing to obtain a mixed material. And (4) performing spark plasma sintering to obtain a hard alloy sintered body. The sintering process adopts the pressure of 20-60 Mpa, the sintering temperature is controlled to be 1000-1500 ℃, and the heat preservation time is 4-10 min. The high-entropy alloy bonding phase is reinforced by a second phase gamma' phase, the density of the obtained hard alloy reaches 96-99.8%,the hardness of the alloy reaches 1100-2300 HV 30 The fracture toughness reaches 9 to 20MNm ‑3/2 The mechanical property of the alloy is better than that of the Co-based binder phase hard alloy commonly used in industry, and the alloy provides a better material choice in the application field of high-performance hard alloy.)

1. A second-phase strengthened high-entropy binder hard alloy is characterized in that: the hard alloy binding phase is high-entropy alloy, and the hard alloy hard phase is WC. The high-entropy alloy powder accounts for 10-30 wt% of the total mass ratio, and the balance is WC powder.

2. The high-entropy alloy powder according to claim 1, wherein: the high-entropy alloy bonding phase comprises the following components in atomic proportion: wherein, Fe, Co, Ni, Al, Ti (Nb, Ta, etc.) 1:1:1: x, y (x <1, y < 1). The purity of the powder reaches more than 99.99 percent.

3. The cemented carbide of claim 1 wherein: the hardness of the sintered sample reaches 1300-1800HV30, the fracture toughness reaches 9-16 MNm-3/2, and the density can reach 97-99.8%.

4. The cemented carbide of claim 1 wherein: the microstructure of the alloy consists of WC hard phase, FCC binding phase and gamma 'phase in the binding phase, and the second phase gamma' phase strengthens the base of the binding phase, thus improving the strength of the hard alloy.

5. A preparation method of hard alloy is characterized by comprising the following steps: the ratio of the powder to the hard alloy balls is 8: 1-20: 1, the ball milling rotation speed is 200-600r/min, the ball milling time is 50-150 h, and 2ml of absolute ethyl alcohol is added as a ball milling medium in the ball milling process.

Mixing the prepared high-entropy alloy powder with WC powder, adding the mixture and hard alloy balls into a ball milling tank according to the proportion of 2: 1-10: 1, mixing for 20-40 h, and adding 2ml of absolute ethyl alcohol as a ball milling medium in the ball milling process.

And after the preparation of the hard alloy powder is finished, placing the hard alloy powder in a mould for spark plasma sintering, wherein the pressure is 20-60 Mpa in the sintering process, the sintering temperature is 1000-1500 ℃, and the high-entropy alloy bonding phase hard alloy with the substrate being an FCC phase and the substrate being strengthened by the second phase is obtained after heat preservation for 4-10 min at the sintering temperature and cooling.

Technical Field

The invention relates to the field of high-entropy alloy and metal ceramic composite material, in particular to a high-entropy alloy added with a second phase, which is applied as a hard alloy binding phase and a preparation method thereof.

Background

The hard alloy is used as a metal ceramic composite material and is formed by compounding a refractory hard substrate and a metal binding phase. The special combination mode can not only have the characteristics of high hardness and high strength, but also have better toughness, so the special combination mode is widely applied to the manufacturing and processing industry, in particular to the aspects of wear-resistant parts, cutting tools and the like. Nowadays, with the rapid development of manufacturing industry, the common Co-based binder phase is difficult to meet the actual demand, and particularly, a great gap still exists between China and the advanced level of the world in the aspect of high-end manufacturing industry.

The hard alloy binding phase generally has better toughness and better wetting degree with the hard phase, so that the crack can be effectively propagated all the time, and the mechanical property of the material is improved. Conventional cemented carbide binder phases are typically metal-based binder phases, especially iron group element-based binder phases, one of the most common of which is a Co-based binder phase.

Co-based bonding in the hard alloy is quite widely applied at present, the wetting degree between the Co-based bonding and WC crystal grains is good, the plasticity and the toughness of the hard alloy can be well improved, but with the rising of the demand of Co in various industries, the problem of Co resource shortage becomes an important factor of the rising of the price of the hard alloy material, the Co-based bonding phase can reduce the hardness, the wear resistance, the oxidation resistance and other properties of the material, and particularly, the WC-Co-based hard alloy shows poor mechanical properties under the severe conditions of high temperature and the like.

At present, the research trend of the novel cemented carbide binding phase is mainly that the oxidation resistance of the cemented carbide can be effectively improved by adding composite metal materials and elements such as Ni, Al and the likeChemical property and the like, thereby better improving the high-temperature mechanical property of the binding phase. As early as 1983, Viswanadham proposed WC- (Ni, Al) -based cemented carbides, which increase the strength of the alloy through precipitation hardening by Al alloying. (Viswanadham R K, Lindquist P G, Peck J A. preference and Properties of WC- (Ni, Al) segmented cardes [ C]International Conference on the Science of Hard materials, springer US, 1983) but marchun et al found that ultra-fine grain WC-Ni3Al cemented carbide: an increase in the Ni3Al content decreases the alloy hardness. (microstructure and Property of Marshmania, Marek's disease, Xiaozahong, et Al. ultra-fine grain WC-Ni-3 Al cemented carbide [ J]Hot working process 2016,45(16):72-75.) Tiegs et al prepared composites doped with oxide ceramic powders and B-containing ductile Ni3Al alloys by hot pressing, the Ni3Al alloy did not wet the oxide powders well and tended to form discrete "island" like metallic phases. (Tiegs T N, Alexander K B, Plucknet K P, et al₃Al binder phase[J].Materials Science&Engineering A (Structural Materials, Properties, Microstructure and Processing),1996,209(1-2):243-247.) high-entropy alloy is one of three major breakthroughs of the recent ten-year alloying theory, and is different from the design concept of the traditional single-principal-element alloy, and the unique high-entropy effect, the delayed diffusion effect and the cocktail effect enable the Microstructure of the multi-principal-element high-entropy alloy to form excellent performances such as high hardness, high wear resistance and high thermal stability. Previously, the research on the high-entropy alloy as the cemented carbide binding phase has started, but due to the lack of deep exploration of the existence of the second phase in the matrix, the performance of the high-entropy alloy binding phase still has great progress space. The method for adding the second phase into the high-entropy alloy strengthens the strength of the high-entropy alloy matrix and improves the performance of the binding phase, thereby better improving the comprehensive mechanical property of the hard alloy.

Disclosure of Invention

The invention provides a hard alloy added with a second-phase high-entropy alloy binding phase and a preparation method thereof, aiming at overcoming the technical defects of the existing industrial hard alloy binding phase.

The prepared high-entropy alloy binding phase is characterized in that: the high-entropy alloy bonding phase comprises the following components in atomic proportion: wherein, Fe, Co, Ni, Al, Ti (Nb, Ta, etc.) 1:1:1: x, y (x <1, y < 1). The particle size of each metal elementary substance powder of the high-entropy alloy binding phase is 200-400 meshes, and the purity reaches 99.99%.

The technical scheme adopted by the invention is as follows:

1. preparing high-entropy alloy powder: weighing the mass of the simple substance powder, putting the weighed powder and the hard alloy balls into a ball milling tank, wherein the ball material ratio is 5: 1-20: 1, adding 2ml of absolute ethyl alcohol, mixing for 50-150 h, rotating at the speed of 200-600r/min, and stopping rotating for 15min every 2h to obtain the high-entropy alloy powder.

2. Hard alloy powder preparation (mixing): mixing the prepared high-entropy alloy powder with 200-400-mesh WC powder, adding the mixed powder and the hard alloy balls into a ball milling tank according to the ratio of 2: 1-10: 1, adding 2ml of absolute ethyl alcohol, and mixing for 20-40 h at the rotating speed of 120-200 r/min to obtain the hard alloy powder.

3. Sintering of hard alloy: and (3) placing the hard alloy powder into a die for spark plasma sintering, raising the pressure to 20-60 MPa when the temperature is raised, raising the temperature to 1000-1500 ℃, preserving the heat for 4-10 min, and cooling to obtain a hard alloy sintered sample with excellent performance.

Furthermore, the prepared high-entropy alloy binding phase is formed by alloying iron, cobalt, nickel, titanium, aluminum and metal simple substance powder, wherein Fe, Co, Ni, Al, Ti (Nb, Ta and the like) is 1:1:1: x, y (x is less than 1, y is less than 1), the content of the second phase in the high-entropy alloy matrix can be increased, and the performance of the high-entropy alloy binding phase is better improved.

Furthermore, the particle size of each metal elementary substance powder of the high-entropy alloy binding phase is 200-400 meshes, and the purity reaches 99.9%.

Compared with the existing cemented carbide binding phase, the invention has the following advantages:

the strength of the high-entropy alloy matrix is increased by adding the second phase, and the excellent comprehensive mechanical property of the high-entropy alloy is greatly improved, so that the mechanical property of the high-entropy alloy is higher than that of other WC (wolfram carbide) hard alloys in the existing hard alloy application field, the high-entropy alloy has a stronger application space, and the application space of the hard alloy in the more advanced technical field can be improved.

Drawings

FIG. 1 is a XRD pattern of FeCoNiAl0.3Ti0.2 alloy at different ball milling times.

FIG. 2 is a microstructure diagram of a FeCoNiAl0.3Ti0.2 alloy.

FIG. 3 XRD pattern of WC-20% (FeCoNiAl0.3Ti0.2) cemented carbide

Detailed Description

The invention is further illustrated by the following examples:

example 1

Step 1, according to atomic percentage: fe, Ni, Co, Al, Ti, 1:1:1:0.4:0.1 five metal powders of iron, cobalt, nickel, aluminum and titanium are weighed.

And 2, ball-milling the powder weighed in the step 1 for 120 hours by using a stellar ball mill, adding 2ml of absolute ethyl alcohol as a process control agent, stopping rotation for 15 minutes at a rotation speed of 350r/min for 2 hours per rotation, and completely mechanically alloying the powder after 60 hours to obtain the high-entropy alloy powder as shown in figure 1.

And 3, weighing the WC powder and the high-entropy alloy powder according to the mass percentage of 7: 3.

And 4, putting the hard alloy powder obtained in the step 3 into a stellar ball mill for ball milling for 24 hours, adding 2ml of absolute ethyl alcohol as a process control agent, rotating at 200r/min, and stopping rotating for 15 minutes every 2 hours to obtain hard alloy mixed powder.

And 5, placing the hard alloy powder in a mould for spark plasma sintering, raising the pressure to 50MPa when the temperature is raised, raising the temperature to 1250 ℃, preserving the heat for 5min, and cooling to obtain a hard alloy sintered sample with excellent performance. As shown in FIG. 3, the XRD pattern of WC-20% (FeCoNiAl0.4Ti0.1) hard alloy shows that a second phase is generated.

The hardness of a sintered sample of FeCoNiAl0.4Ti0.1 binder phase hard alloy is 1195.0HV, the compactness is 99.621 percent, and the fracture toughness is 18.8MNm^-3/2。

Example 2

Step 1, according to atomic percentage: fe, Ni, Co, Al, Ti, 1:1:1:0.2:0.3 five metal powders of iron, cobalt, nickel, aluminum and titanium are weighed.

And 2, ball-milling the powder weighed in the step 1 for 120 hours by using a stellar ball mill, adding 2ml of absolute ethyl alcohol as a process control agent, stopping rotation for 15 minutes at a rotation speed of 350r/min for 2 hours per rotation, and completely mechanically alloying the powder after 60 hours to obtain the high-entropy alloy powder as shown in figure 1.

And 3, weighing the WC powder and the high-entropy alloy powder according to the mass percentage of 8: 2.

And 4, putting the hard alloy powder obtained in the step 3 into a stellar ball mill for ball milling for 24 hours, adding 2ml of absolute ethyl alcohol as a process control agent, rotating at 200r/min, and stopping rotating for 15 minutes every 2 hours to obtain hard alloy mixed powder.

And 5, placing the hard alloy powder in a mould for spark plasma sintering, raising the pressure to 50MPa when the temperature is raised, raising the temperature to 1250 ℃, preserving the heat for 5min, and cooling to obtain a hard alloy sintered sample with excellent performance. As shown in FIG. 2, which is an electron microscope image of WC-20% (FeCoNiAl0.3Ti0.2) hard alloy, the wetting degree of the binding phase and the hard phase is good, and WC grains and the binding phase grains are fine, so that the performance is good. As shown in fig. 3, which is the XRD pattern of WC-20% (feconial0.3ti0.2) cemented carbide, XRD results show that the second phase γ' phase is indeed generated.

The hardness of a sintered sample of FeCoNiAl0.3Ti0.2 binding phase hard alloy is 1807.3HV, the compactness is 99.489 percent, and the fracture toughness is 12.8MNm^-3/2。

Example 3

Step 1, according to atomic percentage: fe, Ni, Co, Al and Ti are weighed, and five metal powders of iron, cobalt, nickel, aluminum and titanium are weighed according to the weight ratio of 1:1:1:0.1: 0.4.

And 2, ball-milling the powder weighed in the step 1 for 120 hours by using a stellar ball mill, adding 2ml of absolute ethyl alcohol as a process control agent, stopping the rotation for 15 minutes at a rotation speed of 350r/min for 2 hours every time, and completely mechanically alloying the powder after 60 hours to obtain the high-entropy alloy powder.

And 3, weighing the WC powder and the high-entropy alloy powder according to the mass percentage of 9: 1.

And 4, putting the hard alloy powder obtained in the step 3 into a stellar ball mill for ball milling for 24 hours, adding 2ml of absolute ethyl alcohol as a process control agent, rotating at 200r/min, and stopping rotating for 15 minutes every 2 hours to obtain hard alloy mixed powder.

And 5, placing the hard alloy powder in a mould for spark plasma sintering, raising the pressure to 50MPa when the temperature is raised, raising the temperature to 1250 ℃, preserving the heat for 5min, and cooling to obtain a hard alloy sintered sample with excellent performance.

The hardness of a sintered sample of FeCoNiAl0.4Ti0.1 binder phase hard alloy is 2196.5HV, the compactness is 98.890 percent, and the fracture toughness is 10.8MNm^-3/2。