CN104388842B - A kind of Fe-Cr-B system corrosion block non-crystaline amorphous metal and preparation method thereof - Google Patents

Abstract

A Fe-Cr-B series corrosion-resistant bulk amorphous alloy and a preparation method thereof belong to the field of amorphous alloys. The chemical composition of the amorphous alloy is designed according to the atomic ratio: Fe _a Cr _b Mo _c B _d M _e R _f X _g . The composition features are: M is one or more of Mn, Co, Ni; R is one or more of Ti, Zr, Nb, Hf, Ta, W; X is one or more of Si, P Various elements. Among them, 20<a≤78, 5≤b≤45, 0≤c≤20, 6≤d≤30, 0≤e≤40, 2≤f≤15, 0≤g≤10, a+b+c+ d+e+f+g=100. The alloy of the present invention is characterized by low cost and can be smelted using industrial raw materials; at the same time, it has high boron content and good amorphous forming ability, and is especially suitable for storage and transportation of nuclear waste; the high Cr content in the alloy without C ensures the Amorphous alloys have excellent corrosion resistance; the amorphous alloys also have extremely high compressive strength and microhardness. Therefore, the iron-based amorphous alloy of the invention has a good application prospect in corrosion protection of metal materials, nuclear facilities and wear-resistant parts.

Description

A kind of Fe-Cr-B series corrosion-resistant bulk amorphous alloy and preparation method thereof

technical field

The invention belongs to the field of amorphous alloys, in particular to an Fe-Cr-B series amorphous alloy with high amorphous forming ability, high boron content and high corrosion resistance.

Background technique

Iron-based amorphous alloys have shown important application value in industry due to their low cost, good glass forming ability, good soft magnetic properties, high wear resistance and high corrosion resistance. Compared with other amorphous alloys, iron-based amorphous alloys can accommodate a high content of B atoms, which can be used as neutron absorbers for nuclear waste without crystallization, and the addition of Cr will significantly improve the quality of iron-based amorphous alloys. corrosion resistance performance. Following the large-scale industrialization of iron-based amorphous soft magnetic alloys, the development and application of wear-resistant and corrosion-resistant iron-based amorphous alloys for coatings has gradually begun.

The high corrosion resistance of iron-based amorphous alloys is firstly due to the fact that amorphous alloys have a single-phase structure, and there are no structural defects such as grain boundaries, dislocations, and stacking faults; secondly, the activity of atoms on the surface of amorphous alloys is very high. Iron-based amorphous with higher Cr can quickly form a uniform fatal passivation film on the surface, making corrosion difficult to occur.

In 1974, Masumoto Ken's research group at Tohoku University in Japan found that the corrosion resistance of Fe ₇₀ Cr ₁₀ P ₁₃ C ₇ amorphous alloy in 1mol/L HCl solution was better than that of traditional 304 stainless steel (Fe-18Cr-8Ni). Japanese patent JPS58113354 discloses a Fe-Cr-Mo amorphous alloy containing P, C or P, Si, which exhibits excellent corrosion resistance in hot hydrochloric acid. Japanese patent JP3805601 discloses a C-containing Fe-Cr-based bulk amorphous alloy, which solves the problem of insufficient amorphous formation ability of previous high-Cr amorphous alloys, in which Fe ₄₅ Cr ₁₅ Mo ₁₅ C ₁₅ B ₁₀ amorphous The critical size of the alloy reaches 2.5mm, and it also has excellent corrosion resistance.

US Patent US7052561B2 discloses a Y-containing amorphous steel. The addition of rare earth element Y further improves the critical size of the Cr-containing Fe-based amorphous alloy, (Fe ₄₃ Cr ₁₆ Mo ₁₆ C ₁₅ B ₁₀ ) ₉₈ Y ₂ and (Fe ₄₅ Co ₅ Cr ₆ Mo ₁₃ Mn ₁₁ C ₁₆ B ₆ ) _98.5 Y _1.5 bulk amorphous alloys have critical dimensions of 7mm and 12mm, respectively.

U.S. Patent US8524053B2 discloses Fe ₄₈ Cr ₁₅ Mo ₁₄ C ₁₅ B ₆ Y ₂ with a critical dimension of 9 mm and high boron composition Fe _49.7 Cr _18.1 Mn _1.9 Mo _7.4 W _1.6 B _15.2 C _3.8 Si _2.4 amorphous Crystal alloys, the alloy grades are named SAM1651 and SAM2X5 respectively. SAM2X5 alloy coating exhibits excellent corrosion resistance in various complex corrosion environments, and has better neutron absorption capacity than traditional neutron absorbing materials.

So far, high-Cr corrosion-resistant iron-based bulk amorphous alloys rely on higher C content or the addition of rare earth elements in the composition. Excessive C content will increase the brittleness of the alloy, and the enrichment of C will accelerate the corrosion of the material, which is an unfavorable factor for the preparation of amorphous alloy coatings; on the other hand, when the C content is high, the amount of B atoms that can be accommodated in the alloy must be Low, which is not conducive to the neutron absorption capacity of the material. The addition of rare earth elements such as Y will increase the cost of raw materials and smelting costs, and the high activity of rare earths may have an adverse effect on the corrosion resistance of the alloy. Therefore, it is of great practical significance to develop iron-based bulk amorphous alloys with high Cr, high B, no C and no rare earth.

So far, the research on high-B, C-free and rare-earth-free Fe-based bulk amorphous alloys has mainly focused on the field of soft magnetic amorphous alloys. For example, Fe ₅₆ Co ₇ Ni ₇ Zr ₁₀ B ₂₀ (2mm), [(Fe _0.6 Co _0.4 ) _0.75 B _0.2 Si _0.05 ] ₉₆ Nb ₄ (4mm), [(Fe _0.8 Ni _0.2 ) _0.75 B _0.2 Si _0.05 ] ₉₆ Nb ₄ (2mm) and other alloy components. None of these components contain Cr element and are not suitable for corrosion-resistant applications.

_In 2009, Wang _Jianqiang and others studied the _{performance of Fe48Cr15Mo14C15B6Y2 amorphous alloy} coating prepared by _supersonic flame spraying technology, and they found that the coating has excellent wear resistance and corrosion resistance. In 2011, Zhang Cheng et al. prepared F _e48 Cr ₁₅ M _o14 C ₁₅ B ₆ Y ₂ amorphous alloy coating by supersonic flame spraying technology, and studied the effect of spray powder particle size on coating structure and its application in simulated seawater environment. effect on corrosion behavior. In 2012, Shen Jun et al prepared _Fe42.87 Cr _15.98 M _o16.33 C _15.94 B _8.88 amorphous alloy coating by plasma spraying technology and studied the corrosion resistance of the coating.

It can be seen that the preparation of the above-mentioned wear-resistant and corrosion-resistant iron-based amorphous alloy coating mainly uses components developed by researchers in Japan and the United States. The United States has commercialized wear-resistant and corrosion-resistant iron-based amorphous alloys relying on Liquidmetal. There is no independent intellectual property rights in this area in China, so the development of new wear-resistant and corrosion-resistant iron-based amorphous alloys is of great significance to fill the domestic gap.

Contents of the invention

The content of the present invention is to develop a Fe-Cr-B series bulk amorphous alloy with high boron content and high corrosion resistance. The alloy of the present invention is characterized by low cost and can be smelted using industrial raw materials; at the same time, it has high boron content and good amorphous forming ability, and is especially suitable for storage and transportation of nuclear waste; the high Cr content in the alloy without C ensures the Amorphous alloys have excellent corrosion resistance. Therefore, the Fe-Cr-B series amorphous alloy of the present invention has a good application prospect in corrosion protection of metal materials, nuclear facilities and wear-resistant parts.

The chemical composition of the Fe-Cr-B series amorphous alloy of the present invention is designed according to the atomic ratio: Fe _a Cr _b Mo _c B _d M _e R _f X _g . The composition features are: M is one or more of Mn, Co, Ni; R is one or more of Ti, Zr, Nb, Hf, Ta, W; X is one or more of Si, P Various elements. Among them, 20<a≤78, 5≤b≤45, 0≤c≤20, 6≤d≤30, 0≤e≤40, 2≤f≤15, 0≤g≤10, a+b+c+ d+e+f+g=100.

In the above alloy, when c=e=g=0, the alloy composition can be expressed as Fe _a Cr _b B _d R _f , and its composition range is expressed as 40≤a≤75, 5≤b≤38, 10≤ d≤25, 4≤f≤15, a+b+d+f=100.

When e=g=0, and R is limited to Zr element, the alloy composition can be expressed as Fe _a Cr _b Mo _c B _d Zr _f , and its composition range is expressed as 30≤a≤75, 5≤b≤40,0 <c≤20, 7≤d≤28, 2≤f≤15, a+b+c+d+f=100.

In the above-mentioned Fe _a Cr _b Mo _c B _d Zr _f alloy, the alloy composition can be further preferred, and its composition range is expressed as 52≤a≤66, 8≤b≤11, 5≤c≤10, 15≤d≤19, 6≤f≤8, a+b+c+d+f=100, the critical dimension of the amorphous alloy reaches 3 mm.

In the above-mentioned Fe _a Cr _b Mo _c B _d Zr _f alloy, the alloy composition can be further preferred, and its composition range is expressed as 35≤a≤57, 25≤b≤40, 0<c≤6, 11≤d≤16, 6≤f≤8, a+b+c+d+f=100, the amorphous alloy has excellent corrosion resistance.

When M is limited to Co element, the alloy composition can be expressed as Fe _a Cr _b Mo _c B _d Co _e R _f X _g , and its composition range is expressed as 20<a≤75, 5≤b≤40, 0≤c ≤20, 7≤d≤28, 0<e≤40, 2≤f≤15, 0≤g≤10, a+b+c+d+e+f+g=100.

In the above-mentioned Fe _a Cr _b Mo _c B _d Co _e R _f X _g alloy, the alloy composition can be further preferably Fe _a Cr _b B _d Co _e Zr _f Si _g , and its composition range is expressed as 21≤a≤35,8 ≤b≤11, 17≤d≤19, 30≤e≤40, 6≤f≤8, 2≤g≤4, a+b+d+e+f+g=100, the critical size of the amorphous alloy reaches 3mm.

When M is limited to Ni element, the alloy composition can be expressed as Fe _a Cr _b Mo _c B _d Ni _e R _f X _g , and its composition range is expressed as 30≤a≤75, 5≤b≤40, 0≤c ≤20, 7≤d≤28, 0<e≤25, 2≤f≤15, 0≤g≤10, a+b+c+d+e+f+g=100.

The preparation method of the bulk amorphous alloy adopted in the present invention comprises: (1) the purity of the raw material Fe, Co or Ni used is not less than 99.5%, the purity of Cr or Si is not less than 99%, and the purity of B or Mo is respectively industrial Add in the form of ferroboron or industrial ferromolybdenum, and the purity of the rest of the raw materials is not less than 99.9%; (2) Use sandpaper and a grinder to remove the surface oxide skin of the metal raw materials, accurately weigh and proportion according to the molar ratio, and use ethanol ultrasonic cleaning Raw materials; (3) use a vacuum non-consumable tungsten electrode electric arc furnace to smelt the alloy, evacuate the furnace body to a vacuum degree ≤ 1×10 ^-2 Pa, and fill it with pure argon until the pressure in the furnace reaches 0.4-0.5 atmospheres; ( 4) The alloy is smelted 3-5 times to ensure uniform smelting; (5) After the alloy smelting is completed, use a grinder to remove the scale, take an appropriate weight and use anhydrous ethanol to clean it ultrasonically, and then use the vacuum suction casting equipment supporting the electric arc furnace and Copper molds were used to prepare cylindrical bulk amorphous alloys.

The iron-based bulk amorphous alloy of the invention has excellent mechanical properties and corrosion resistance. _The strength _{of Fe 57 Cr 12 Mo 5 Zr 8} B ₁₈ bulk amorphous alloy exceeds _4GPa , _{and the microdimensional} The hardness values are 1161 and 1226 respectively. The self-corrosion potential of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ bulk amorphous alloy in 1moL/L hydrochloric acid is -193.4mV, and the corrosion rate is 6.3μm/year; Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ pieces The self-corrosion potential of bulk amorphous alloy in 1moL/L hydrochloric acid is 15.6mV, and the corrosion rate is 2.6μm/year. The corrosion resistance of amorphous alloys increases with the increase of Cr content, which is far superior to the traditional crystalline material 316L stainless steel.

Description of drawings

Fig. 1 is the X-ray diffraction pattern (copper target) of the Fe ₅₇ Cr ₁₀ Mo ₇ Zr ₈ B ₁₈ bulk amorphous alloy with a diameter of 3 mm of the present invention.

Fig. 2 is the X-ray diffraction pattern (molybdenum target) of Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ and Fe ₆₇ Cr ₁₀ Nb ₄ B ₁₆ Si ₃ bulk amorphous alloys of the present invention with a diameter of 1 mm.

Fig. 3 is a graph showing the variation trend of the critical dimension of the FeCrZrB bulk amorphous alloy of the present invention with the increase of Cr content.

Fig. 4 is a graph showing the change trend of the critical dimension of the Fe ₆₅ Cr ₁₀ (Zr _6-x Nb _x ) B ₁₆ Si ₃ bulk amorphous alloy according to the present invention with the change of Zr and Nb content.

Fig. 5 is a graph showing the change trend of the critical dimension of the FeCrMoZrB bulk amorphous alloy of the present invention with the increase of Cr content.

Fig. 6 is a graph showing the change trend of the critical dimension of the Fe _67-x Cr _x Mo ₇ Zr ₈ B ₁₈ bulk amorphous alloy of the present invention with the increase of Cr content.

Fig. 7 is a graph showing the change trend of the critical dimension of the Fe _64-x Cr ₁₀ Mo _x Zr ₈ B ₁₈ bulk amorphous alloy of the present invention with the increase of Mo content.

Fig. 8 is a graph showing the change trend of the critical dimension of the Fe _65-x Cr ₁₀ Mo ₇ Zr _x B ₁₈ bulk amorphous alloy of the present invention with the increase of Zr content.

Fig. 9 is a graph showing the change trend of the critical dimension of the Fe _75-x Cr ₁₀ Mo ₇ Zr ₈ B _x bulk amorphous alloy of the present invention with the increase of B content.

Fig. 10 is a graph showing the change trend of the critical dimension of the _FeCrMoZrBSix bulk amorphous alloy of the present invention with the increase of Si content.

Fig. 11 is a graph showing the change trend of the critical dimension of the Fe _73-x Cr _x Mo ₂ Zr ₆ B ₁₆ Si ₃ bulk amorphous alloy of the present invention with the increase of Cr content.

Fig. 12 is a graph showing the change trend of the critical dimension of the Fe _65-x Cr ₁₀ Mo _x Zr ₆ B ₁₆ Si ₃ bulk amorphous alloy of the present invention with the increase of Mo content.

Fig. 13 is a graph showing the change trend of the critical dimension of the Fe _65-x Co _x Cr ₈ Mo ₂ Zr ₆ B ₁₆ Si ₃ bulk amorphous alloy of the present invention with the increase of Co content.

Fig. 14 is a DSC curve of the Fe ₅₇ Cr ₁₀ Mo ₇ Zr ₈ B ₁₈ bulk amorphous alloy of the present invention.

Fig. 15 is a compressive stress-strain curve of Fe ₅₇ Cr ₁₀ Mo ₇ Zr ₈ B ₁₈ and Fe ₅₇ Cr ₁₂ Mo ₅ Zr ₈ B ₁₈ bulk amorphous alloys of the present invention.

Fig. 16 is a cyclic polarization curve of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ and Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ bulk amorphous alloys in 1 mol/L hydrochloric acid of the present invention.

detailed description

The present invention will be specifically introduced from three aspects of composition design, alloy preparation and performance testing.

1. Composition design

Design Fe _a Cr _b Mo _c B _d M _e R _f X _g alloys with different compositions, the composition characteristics are: M is one or more of Mn, Co, Ni; R is Ti, Zr, Nb, Hf, One or more of Ta and W; X is one or more of Si and P. Among them, 20<a≤78, 5≤b≤45, 0≤c≤20, 6≤d≤30, 0≤e≤40, 2≤f≤15, 0≤g≤10, a+b+c+ d+e+f+g=100.

Fe and Cr are the basic components of the alloy system, and B elements are indispensable amorphous forming elements; Zr and Nb are large atoms with large negative heat of mixing with the main components, which can further improve the amorphous forming ability of the alloy, and Ti , Hf, Ta, W can be partially replaced as neighbor elements. Design composition Fe _a Cr _b B _d R _f .

As a congener element of Cr, the addition of Mo can further improve the amorphous forming ability and mechanical properties of the alloy, and the addition of Mo can further enhance the corrosion resistance of the alloy, especially the pitting corrosion resistance. Zr is a large atom, which has a large negative heat of mixing with Fe, Cr, Mo, and B, and is one of the key elements to improve the ability of alloys to form amorphous. Design composition Fe _a Cr _b Mo _c B _d Zr _f .

Co is a similar element to Fe, and the composition of Fe _a Cr _b Mo _c B _d Co _e R _f X _g was designed to study the effect of Co addition on the amorphous formation ability of the alloy.

Ni is a similar element to Fe, and the design composition Fe _a Cr _b Mo _c B _d Ni _e R _f X _g was used to study the effect of Ni addition on the amorphous formation ability of the alloy.

2. Alloy preparation

Ingredients: The purity of the raw materials Fe, Co or Ni used is not less than 99.5%, the purity of Cr or Si is not less than 99%, B or Mo are provided by industrial ferroboron or industrial ferromolybdenum respectively, and the purity of other metal raw materials is not low At 99.9%. According to the set ingredients, the raw materials are accurately weighed and proportioned according to the molar ratio. The main components and impurities of industrial ferroboron and industrial ferromolybdenum used are shown in Table 1.

The main chemical composition (wt %) of the industrial ferroboron and industrial molybdenum iron that the experiment of table 1 adopts

Preparation of alloy rods: Use a vacuum non-consumable tungsten electrode electric arc furnace to smelt the alloy, evacuate the furnace body to a vacuum degree ≤ 1×10 ^-2 Pa, and fill it with pure argon until the pressure in the furnace reaches 0.4-0.5 atmospheres. In order to ensure that the alloy is fully smelted and uniform, the ingredients containing refractory metals such as Nb and W are smelted first for Fe-Nb and Fe-W master alloys. The master alloy needs to be fully smelted for 3-5 times until it is uniform. Take a suitable quality alloy from the uniformly smelted master alloy, melt it in a non-consumable tungsten electrode electric arc furnace, and then suck it into a copper mold through vacuum suction casting equipment for rapid cooling and forming. According to the different components, prepare a diameter of 1-4mm. alloy rod.

3. Alloy performance test

1) X-ray diffraction (XRD) test

Use an X-ray diffractometer to analyze the phase composition of the sample. For the convenience of testing, different test equipment is used for samples with different diameters. Samples with a diameter of 2mm and above are tested with Cu target XRD equipment, with a scan step of 0.02s ^-1 and a scan angle The 2θ ranges from 10° to 90°; samples with a diameter of 1.5mm and below are tested using Mo target XRD equipment.

Accompanying drawing 1 is the XRD curve (Cu target) of the Fe ₅₇ Cr ₁₀ Mo ₇ Zr ₈ B ₁₈ alloy rod with a diameter of 3 mm. The curve shows a broad steamed bread peak and no crystal peak, indicating that the test sample is amorphous.

Accompanying drawing 2 is the XRD curve (Mo target) of Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ and Fe ₆₇ Cr ₁₀ Nb ₄ B ₁₆ Si ₃ alloy rods with a diameter of 1 mm. Both curves show broad steamed bread peaks, without A crystalline peak, indicating that the test sample was amorphous.

Accompanying drawing 3 shows the influence of the change of Cr content on the amorphous formation ability of FeCrZrB alloy. It can be seen from Table 1 that with the increase of Cr content, the critical size of the alloy shows a trend of first increasing and then decreasing. When the Cr content exceeds 40 %, bulk amorphous alloys cannot be obtained. It can be seen from Table 1 that as the Cr content increases, the B content of the alloy components gradually decreases, which is consistent with the change trend of the eutectic point of the Fe-Cr-B phase diagram.

Figure 4 shows the effect of replacing Zr with Nb on the amorphous formation ability of Fe ₆₅ Cr ₁₀ (Zr _6-x Nb _x )B ₁₆ Si ₃ alloy. It can be seen from the figure that as the Nb content increases, the amorphous formation ability of the alloy first increases and then decreases. Zr and Nb are similar large atoms, and bulk amorphous alloys can be obtained with all Zr or all Nb components.

Table 1 FeCrZrB alloy composition and its amorphous forming ability

Table 2 FeCrMoZrB alloy composition and its amorphous formation ability

Figure 5 shows the influence of Cr content changes on the amorphous formation ability of FeCrMoZrB bulk amorphous alloys. It can be seen from Table 2 that, similar to the composition of FeCrZrB, as the Cr content increases, the critical size of the alloy first increases and then decreases. The tendency is that when the Cr content reaches 45%, the bulk amorphous alloy cannot be obtained. Similarly, as the Cr content increases, the B content of the alloy composition decreases gradually. Combining with Figure 1, it can be found that the addition of Mo greatly improves the formation range and critical size of the bulk amorphous alloy of the alloy, because the addition of Mo reduces the melting point of the alloy and makes it closer to the eutectic composition while increasing the alloy Chaos in liquid state.

Accompanying drawing 6 shows the effect of the change of Cr content on the amorphous formation ability of Fe _67-x Cr _x Mo ₇ Zr ₈ B ₁₈ bulk amorphous alloy. With the increase of Cr content, the critical size of the alloy shows that it first increases and then decreases When the Cr content is 10, the alloy has better amorphous formation ability.

Figure 7 shows the effect of Mo content change on the amorphous formation ability of Fe _64-x Cr ₁₀ Mo _x Zr ₈ B ₁₈ bulk amorphous alloys. With the increase of Mo content, the critical size of the alloy first increases and then decreases When the Mo content is between 5 and 9, the amorphous formation ability of the alloy is better.

Figure 8 shows the effect of Zr content change on the amorphous formation ability of Fe _65-x Cr ₁₀ Mo ₇ Zr _x B ₁₈ bulk amorphous alloy. With the increase of Mo content, the critical size of the alloy first increases and then decreases When the Zr content is between 6 and 8, the amorphous formation ability of the alloy is better.

Figure 9 shows the effect of B content changes on the amorphous formation ability of Fe _75-x Cr ₁₀ Mo ₇ Zr ₈ B _x bulk amorphous alloys. With the increase of B content, the critical size of the alloy first increases and then decreases the trend of. When the B content is 8, the bulk amorphous alloy can still be obtained, which is currently the iron-based bulk amorphous alloy with the lowest metalloid content. When the B content is between 14 and 18, the alloy has better amorphous forming ability.

Figure 10 shows the effect of Si addition on the amorphous formation ability of FeCrMoZrB bulk amorphous alloy. The addition of Si will cause the alloy to deviate from the eutectic composition, which is detrimental to the alloy's amorphous formation ability, but the overall effect is small . Table 3 shows the alloy composition and its amorphous forming ability of some Si additions.

Table 3 FeCrMoZrBSi alloy composition and its amorphous formation ability

Figure 11 shows the effect of Cr content change on the amorphous formation ability of Fe _73-x Cr _x Zr ₆ Mo ₂ B ₁₆ Si ₃ bulk amorphous alloy. With the increase of Cr content, the alloy's amorphous formation ability gradually decreases.

Figure 12 shows the effect of Mo content change on the amorphous formation ability of Fe _65-x Cr ₁₀ Mo _x Zr ₆ B ₁₆ Si ₃ bulk amorphous alloys. With the increase of Mo content, the critical size of the alloy increases first and then decreasing trend.

Co is the most similar element to Fe, and the substitution of Co in Fe-based amorphous alloys is very common and can often improve the amorphous-forming ability of the alloy. The alloy composition and its amorphous formation ability of partially added Co are shown in Table 4. It can be seen that the replacement of Fe by Co has an obvious beneficial effect on the amorphous formation ability of the alloy, and at the same time can increase the B atom content that the alloy can accommodate.

Figure 13 shows the effect of Co substitution on the amorphous formation ability of Fe _65-x Co _x Cr ₈ Mo ₂ Zr ₆ B ₁₆ Si ₃ bulk amorphous alloy. With the increase of Co content, the critical size of the alloy shows a first increase. trend of decreasing after increasing. However, combined with Table 4, it can be found that when the B content is increased, the critical dimension of the amorphous alloy is significantly increased. Therefore, the addition of Co is generally beneficial to the amorphous-forming ability of the alloy.

Ni is a similar element to Fe. In some iron-based amorphous alloy systems, the addition of Ni is beneficial to the alloy's amorphous-forming ability, but in Cr-containing iron-based amorphous alloys, the addition of Ni is rarely reported. In our study, it was found that the addition of Ni had an obvious adverse effect on the amorphous-forming ability of the alloy. Table 5 shows the composition of the Ni-added amorphous alloy and its amorphous-forming ability.

Table 4 Co-containing alloy composition and its amorphous-forming ability

Table 5 Composition of Ni-containing alloys and their amorphous-forming ability

Table 6 Alloy Composition and Its Amorphous Formation Ability

In the aforementioned Fe _a Cr _b Mo _c B _d M _e R _f X _g alloy, the appropriate addition of other metal elements such as Al, Ti, V, Mn, Cu, Ga, Sn, Hf, Ta, W, etc. can form lumps For bulk amorphous alloys, the adverse effect of adding P is more significant than that of metalloid Si. Examples of some alloy compositions and their amorphous performance capabilities are shown in Table 6.

2) Differential scanning calorimetry (DSC) analysis

A differential scanning calorimeter was used to analyze the thermodynamic properties of the amorphous alloy sample, the heating rate was 20K/min, and the heating range was 300K-1600K.

Accompanying drawing 14 is the DSC curve of the measured Fe ₅₇ B ₁₈ Zr ₈ Cr ₁₀ Mo ₇ bulk amorphous alloy. From the DSC curve, it can be seen that the supercooled liquid phase region unique to amorphous materials, and some bulk amorphous alloys The thermodynamic parameters are shown in Table 7.

Table 7 Thermodynamic parameters of iron-based bulk amorphous alloys

3) Quasi-static compression test

The prepared amorphous alloy test rod was cut and polished into a compressed sample with a length-to-diameter ratio of 2:1 to ensure that the two end faces were smooth and perpendicular to the axial direction. A room temperature compression test was carried out on a CMT 4305 universal electronic testing machine with a compression rate of 2 ×10 ^-4 s ^-1 , select at least 3 samples for each alloy composition to test.

Accompanying drawing 15 is the compressive stress-strain curve of Fe ₅₇ B ₁₈ Zr ₈ Cr ₁₀ Mo ₇ and Fe ₅₇ B ₁₈ Zr ₈ Cr ₁₂ Mo ₅ bulk amorphous alloys. It can be seen from the figure that Fe ₅₇ B ₁₈ Zr ₈ The compressive strength of Cr ₁₀ Mo ₇ bulk amorphous alloy is about 3.6GPa, the elastic deformation is about 1.8%, and the elastic modulus is 202GPa; the compressive strength of Fe ₅₇ B ₁₈ Zr ₈ Cr ₁₂ Mo ₅ bulk amorphous alloy exceeds 4GPa, The elastic deformation is about 2%, and the elastic modulus is 208GPa.

4) Microhardness test

The microhardness of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ and Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ bulk amorphous alloys was tested on a micro Vickers hardness tester with a loading force of 200g and a test environment temperature of 20 ℃.

The micro-Vickers hardness value of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ bulk amorphous alloy is 1161 (11.39GPa), and the microscopic hardness of Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ bulk amorphous alloy is 1161 (11.39GPa). The Vickers hardness value is 1226 (12.02GPa). The test results show that the two bulk amorphous alloys have extremely high microhardness, and the microhardness of the material can reflect its wear resistance. Generally speaking, the higher the microhardness, the better the wear resistance of the material. Although the metalloid B content of the Cr35 composition is low, its microhardness is higher compared with the Cr18 composition due to the high Cr content in the composition.

5) Electrochemical test

Test the cyclic polarization curve of the bulk amorphous alloy at the electrochemical workstation, the reference electrode is a saturated calomel electrode, the corrosion solution is 1mol/L hydrochloric acid solution, the test environment temperature is 30°C, and the surface of the sample to be tested needs to be polished. . According to the test standard of ASTM cyclic polarization curve, the scanning potential starts from the relative open circuit potential -300mV, and when the current density reaches 1mA/ ^cm2 , the negative direction potential scanning starts until the potential reaches the relative open circuit potential -300mV, and the scanning speed is 1mV /s.

From the cyclic polarization curves in Figure 16, it can be seen that the bulk amorphous alloys of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ and Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ both behave in 1mol/L hydrochloric acid solution Excellent corrosion resistance performance. The self-corrosion potential of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ amorphous alloy in 1mol/L hydrochloric acid solution is -193.4mV, the corrosion rate is 6.3μm/year, and the passive current density is less than 5×10 ^-5 A/ cm ² , when the potential reaches about 925mV, pitting occurs, the passivation film is destroyed, and the protection potential is 870mV. The self-corrosion potential of Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ amorphous alloy in 1mol/L hydrochloric acid solution is 15.6mV, the corrosion rate is 2.6μm/year, and the passive current density is less than 1×10 ^-5 A/cm ^2. When the potential reaches about 935mV, pitting occurs, the passivation film is destroyed, and the protection potential is 910mV.

Table 8 shows the electrochemical performance parameters of Fe ₅₇ Cr ₁₈ Mo ₂ Zr ₈ B ₁₅ and Fe ₄₃ Cr ₃₅ Mo ₂ Zr ₈ B ₁₂ bulk amorphous alloys in 1mol/L hydrochloric acid solution, with 316L stainless steel as a comparison.

Table 8 Electrochemical parameters

Among them, E _corr is the self-corrosion potential, which is the potential at which the total speed of the anodic reaction is equal to the total speed of the cathodic reaction, indicating the difficulty of corrosion initiation; i _corr is the self-corrosion current density, which can be converted into corrosion rate; v is the corrosion rate; E _b is the breakdown potential, which is the potential at which the passivation film is destroyed and pitting occurs; E _p is the protection potential, which is the potential at the intersection point of the anode curve during cyclic polarization retrace, which characterizes the passivation film of the material after pitting occurs self-healing ability. In addition to the above parameters, the passive current density i _pass is also an important parameter to evaluate the corrosion resistance of materials, but it is not constant in many cases, so it is not given separately.

Since 316L stainless steel corrodes quickly in hydrochloric acid, there is no breakdown potential and protection potential. Comparing the data, it can be found that the corrosion resistance of the above two amorphous alloys in hydrochloric acid is far superior to that of the conventional crystalline material 316L stainless steel.

The foregoing is the basic principle and main features of the present invention. The above embodiments do not limit the present invention in any way, and the technical solutions obtained by simply changing the above embodiments are within the protection scope of the present invention.

Claims (7)

1. A Fe-Cr-B series bulk amorphous alloy, whose composition is expressed as Fe _a Cr _b B _d R _f , characterized in that 40≤a≤75, 5≤b≤38, 10≤d≤25, 4≤f≤15, a+b+d+f=100, R is one or more of Ti, Zr, Nb, Hf, Ta, W. 2. A Fe-Cr-B bulk amorphous alloy whose composition is expressed as Fe _a Cr _b Mo _c B _d Zr _f , characterized in that 30≤a≤75, 5≤b≤40, 0<c≤ 20, 7≤d≤28, 2≤f≤15, a+b+c+d+f=100. 3. A Fe-Cr-B bulk amorphous alloy according to claim 2, whose composition is expressed as Fe _a Cr _b Mo _c B _d Zr _f , characterized in that 52≤a≤66, 8≤b ≤11, 5≤c≤10, 15≤d≤19, 6≤f≤8, a+b+c+d+f=100, the critical dimension of the amorphous alloy reaches 3mm. 4. A Fe-Cr-B bulk amorphous alloy according to claim 2, whose composition is expressed as Fe _a Cr _b Mo _c B _d Zr _f , characterized in that 35≤a≤57, 25≤b ≤40, 0<c≤6, 11≤d≤16, 6≤f≤8, a+b+c+d+f=100, the amorphous alloy has excellent corrosion resistance. 5. A Fe-Cr-B bulk amorphous alloy whose composition is expressed as Fe _a Cr _b B _d Co _e Zr _f Si _g , characterized in that 21≤a≤35, 8≤b≤11, 17≤ d≤19, 30≤e≤40, 6≤f≤8, 2≤g≤4, a+b+d+e+f+g=100, the critical dimension of the amorphous alloy reaches 3mm. 6. A Fe-Cr-B bulk amorphous alloy, the composition of which is expressed as Fe _a Cr _b Mo _c B _d Ni _e R _f X _g , characterized in that 30≤a≤75, 5≤b≤40, 0≤c≤20, 7≤d≤28, 0<e≤25, 2≤f≤15, 0≤g≤10, a+b+c+d+e+f+g=100, R is Ti, One or more of Zr, Nb, Hf, Ta, W; X is one or more of Si and P. 7. A method for preparing the Fe-Cr-B series bulk amorphous alloy according to one of claims 1-6, characterized in that: (1) the purity of the raw material Fe, Co or Ni used is not less than 99.5% , the purity of Cr or Si is not less than 99%, B or Mo is added in the form of industrial ferroboron or industrial molybdenum respectively, and the purity of the rest of the raw materials is not less than 99.9%; (2) Use a vacuum non-consumable tungsten electrode electric arc furnace To smelt the alloy, evacuate the furnace body to a vacuum degree ≤ 1×10 ^-2 Pa, and fill the furnace with pure argon until the pressure in the furnace reaches 0.4-0.5 atmospheres; (3) The alloy is smelted 3-5 times to ensure uniform smelting; ( 4) After the alloy smelting is completed, the cylindrical bulk amorphous alloy is prepared by using the vacuum suction casting equipment and the copper mold matched with the electric arc furnace.