CN102732763B - High-strength Mg-Gd-Y-Zn-Mn alloy - Google Patents

Abstract

The invention relates to a high-strength Mg-Gd-Y-Zn-Mn alloy, which includes the following alloying elements distributed in the alloy and their percentage weight content values: Gd=8.2-10.2, Y=5.0-6.0, Zn= 0.5~4.0, Mn=0.5~0.8, the balance is magnesium and unavoidable impurities; it is prepared by the following process: batching, vacuum melting ingot casting, homogenizing annealing, extrusion and heat treatment. The present invention proposes that Mg, Zn, Gd, and Y form a large number of long-period phases in the Mg-Gd-Y-Zn-Mn alloy, which can have a significant dispersion strengthening effect, and then introduce the strengthening effect of the metastable phase through aging treatment, The process is a preparation method of a high-strength wrought magnesium alloy integrating solid solution strengthening, precipitation strengthening and deformation strengthening. The invention has the advantages of simple process, strong portability, easy operation and low cost, obviously improves the room temperature tensile strength and yield strength of the alloy, solves the problem that the application of the Mg alloy is limited due to low mechanical properties, and expands the scope of the magnesium alloy. application range.

Description

A High Strength Mg-Gd-Y-Zn-Mn Alloy

technical field

The invention relates to a deformed magnesium alloy and a manufacturing method thereof, in particular to a high-strength Mg-Gd-Y-Zn-Mn alloy. The alloy is a five-element magnesium alloy comprising Mg, Gd, Y, Zn and Mn five alloying elements, the high strength refers to the material can achieve a tensile strength ≥ 495MPa.

Background technique

The elastic modulus of magnesium is relatively small, and it can produce large deformation under the action of force. Therefore, under the action of impact load, magnesium alloy can absorb large impact energy and can manufacture impact-resistant parts. Magnesium and its alloys, as the lightest commonly used metal structural materials, have attracted more and more attention, and have been applied to a certain extent in the fields of national defense, aerospace, high-speed rail transportation, and electronic communications. However, due to the low strength of magnesium alloys, it is difficult to be widely used in load-bearing structural parts, especially the application of deformed magnesium alloys is still far behind steel and aluminum alloys, and its mechanical properties at room temperature are obviously insufficient, which has seriously restricted its further development. application.

CN200810230077.2 discloses "a high-strength cast magnesium alloy and its melting method". The mass percentages of its components are: Gd: 8.1-11.5%, Y: 1.0-4.5%, RE: 0.01-3.0 %, Zn: 0.01～0.2%, Mn: 0～0.18%, Zr≤1.0%, and (Gd+Y+RE)≤15.5%; the balance is Mg and impurities. With Gd and Y as the main alloying elements, multiple rare earth RE, Zn and Mn as auxiliary alloying elements, and Be and Ca are used to further reduce alloy oxidation and Zr is used for refining treatment. The alloy has high strength and excellent heat resistance. It is suitable for The casting method makes the workpiece. However, due to the complex formula and the wide use of rare earth elements, the preparation difficulty is increased. The best mechanical properties obtained are the Mg-8.1Gd-4.5Y-0.11La-0.06Pr-0.41Nd-0.96Sm0.57Dy-0.35Er-0.3Yb-0.12Ho-0.01Zn cast alloy T6 state at room temperature The tensile strength is 395MPa, but the elongation is only 4.0%, which limits its performance and application range. Moreover, the alloy of the invention is a cast magnesium alloy, the shape and size of the castings have certain limitations and are prone to structural defects, and the alloy of the invention still adds Mg-Zr master alloy as a grain refiner while using a large amount of rare earth elements , which increases the alloy cost.

CN200610144003.8 discloses "a magnesium alloy and its preparation method". The composition content of the magnesium alloy is: Gd: 7-11wt%, Y: 2-5wt%, Zr: 0.3-0.6wt%, Zn: 0- 1.0wt%, the rest is Mg and unavoidable impurity elements. The best mechanical performance data at room temperature after solid solution, extrusion and aging treatment of the patented alloy as cast state are tensile strength of 450-480 MPa and elongation of 3-5%. The price of metal Zr and its alloys is significantly higher than that of metal Mn and its alloys, which will increase the cost of the alloy, and the elongation of the alloy is low.

Therefore, choose to add alloy elements to magnesium to obtain a diversified magnesium alloy system, use conventional equipment to obtain its as-cast alloy and process the as-cast alloy into an extruded alloy, and perform appropriate heat treatment on the extruded alloy. Strengthening means to increase the strength of magnesium alloys, improve the comprehensive mechanical properties and serviceability of magnesium alloys, and expand their application range have become problems to be solved by those skilled in the art.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is how to improve the strength of the magnesium alloy, provide a high-strength Mg-Gd-Y-Zn-Mn alloy, realize the purpose of simple process, easy operation and cost reduction .

To achieve the above object, the technical solution adopted in the present invention is: a high-strength Mg-Gd-Y-Zn-Mn alloy; it is characterized in that the magnesium alloy is mainly composed of Mg, Gd, Y, Zn and Mn, and each composition The mass percentage of ingredients is: Gd=8.2～10.2, Y=5.0～6.0, Zn=0.5～4.0, Mn=0.5～0.8, and the balance is magnesium and unavoidable impurities;

The alloy is prepared as follows:

(1) Calculate the weight of the required raw materials according to the above components. The raw materials are industrial pure magnesium, industrial pure zinc, Mg-Gd master alloy, Mg-Y master alloy, Mg-Mn master alloy; the alloy ingot is obtained by vacuum melting and casting ;

(2) Perform homogenization annealing treatment on the alloy ingot obtained in step (1), the process parameters are: temperature 540°C±10°C, time 4 hours; then extrude the prepared billet to obtain the extruded alloy, The process parameters adopted are: extrusion temperature 400°C±10°C, extrusion ratio 11, extrusion on the extrusion machine, extrusion speed is constant;

(3) Perform artificial aging treatment on the extruded alloy after deformation processing in step (2). The process parameters are: aging temperature 200°C, holding time 50 hours, and air cooling to obtain a high-strength magnesium alloy material.

Further, in step (1), the vacuum smelting and casting is to add the raw materials into the crucible and pass in argon gas for protection, and melt in a vacuum smelting furnace; keep warm at 850°C and stir by electromagnetic induction to fully melt the raw materials, and wait until the alloy is completely After melting, continue to stand at 850°C for 10 minutes.

The preferred formula is: the mass percentage of each composition of the magnesium alloy is: Gd-8.4%, Y-5.3%, Zn-1.65%, Mn-0.6%, the total content of impurities <0.1%; the balance is magnesium.

The inevitable impurities in the present invention are Si and Fe, the total amount of which is less than 0.1%.

After a large number of experimental studies, the inventor believes that: Mg, Zn, Gd, and Y can form long-period phases in magnesium alloys, and these long-period phases, as new hard phases in the magnesium matrix, can play a significant role in dispersion strengthening , and then introduce the strengthening effect of the metastable phase through aging treatment, taking into account the solid solution strengthening, dispersion strengthening and precipitation strengthening mechanisms, so that the room temperature mechanical properties of magnesium alloys can be improved.

The high-strength Mg-Gd-Y-Zn-Mn alloy is not powder metallurgy, but the as-cast alloy is obtained by smelting and casting, and then extruded, and then the extruded alloy is subjected to aging heat treatment to obtain the final alloy.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention proposes to make Mg, Zn, Gd, and Y form a large number of long-period phases in the Mg-Gd-Y-Zn-Mn alloy, and these long-period phases, as new hard phases in the magnesium matrix, can play a significant role in dispersion strengthening Effect, and then introduce the strengthening effect of the metastable phase through aging treatment. This process is a preparation method of high-strength wrought magnesium alloy integrating solid solution strengthening, precipitation strengthening and deformation strengthening.

In the Mg-Gd-Y-Zn alloy, in addition to the good strengthening and toughening effect of the LPSO phase, the system alloy also has a significant aging strengthening effect. The main contributors to the aging strengthening are the massive precipitation of the metastable β" phase (hexagonal close-packed superlattice structure) and the β?? stable phase, the LPSO structural phase will continue to precipitate. The appearance of the LPSO phase can reduce the total energy of the system, activate the basal plane dislocation movement, and improve the plasticity of the alloy. Combined with the precipitation strengthening effect of the metastable phase, the alloy has become a high-strength Potential of magnesium alloys.

Although the Zr element has an effective grain refinement effect, Zr is easy to form Zn ₃ Zr ₂ intermetallic compounds with Zn during the alloy casting process, which reduces the effect of grain refinement. Severe segregation and segregation are prone to occur, forming coarse elemental particle aggregation, and deteriorating the melting quality and mechanical properties of the alloy. Moreover, during smelting, the utilization rate of Mg-Zr master alloy is very low, and its price is very expensive, and the smelting cost is very high. Other studies have shown that in addition to the advantages of improving the corrosion performance of the alloy and removing harmful elements such as Fe, Mn is dispersed in the magnesium alloy in the form of a single substance, which can also refine dendrites and hinder dynamic regeneration during hot extrusion. The crystallization grain grows and the grain grows during the subsequent heat treatment, and the grain size of the alloy decreases with the increase of Mn content. The present invention replaces Zr element with Mn, and prepares a high-strength Mg-9Gd-6Y-1.6Zn-0.6Mn (wt.%) alloy.

Just take the following high-strength Mg-Gd-Y-Zn-Mn alloy as an example, which has high mechanical properties, in which the aged Gd -8.4wt%, Y -5.3wt%, Zn -1.65wt%, Mn -0.6 wt%; the balance is Mg and a small amount of impurities; the room temperature tensile strength of the alloy is 496MPa, the yield strength is 324MPa, and the elongation is 9.7%; its strength is significantly improved compared with the currently commonly used deformed magnesium alloys AZ91 and ZK60.

The high-strength Mg-Gd-Y-Zn-Mn alloy is not powder metallurgy, but an alloy obtained by smelting and casting an as-cast alloy, extruding, and then performing appropriate heat treatment on the extruded alloy.

The addition of rare earth metals in the present invention introduces LPSO phase and metastable phase, which can significantly improve the room temperature strength and toughness of magnesium alloys, and replace Zr elements with Mn elements, which is also conducive to improving the corrosion resistance of alloys and reducing alloy costs. The expansion of alloy application fields has created conditions.

The invention has a simple process, the equipment used is conventional general equipment, has strong portability, is easy to operate, and has low cost. Difficulties, expanding the scope of application of magnesium alloys.

Description of drawings

Fig. 1 is a picture of the metallographic structure of the alloy in the aging state of Example 1 of the present invention.

Detailed ways:

The high-strength Mg-Gd-Y-Zn-Mn alloy of the present invention is a five-element magnesium alloy, including five alloy elements of Mg, Gd, Y, Zn and Mn, and the high strength refers to the tensile strength that the material can achieve ≥495MPa.

After a large number of experimental studies, the inventor believes that: Mg, Zn, Gd, and Y can form long-period phases in magnesium alloys, and these long-period phases, as new hard phases in the magnesium matrix, can play a significant role in dispersion strengthening , and then introduce the strengthening effect of the metastable phase through aging treatment, taking into account the mechanisms of solid solution strengthening, dispersion strengthening and precipitation strengthening, so as to improve the mechanical properties of magnesium alloys at room temperature.

Example 1: A high-strength Mg-Gd-Y-Zn-Mn alloy, alloy composition (weight percent): Gd-8.4%, Y-5.3%, Zn-1.65%, Mn-0.6%, and impurity elements are less than 0.1%, the rest is Mg.

The manufacture method of this high-strength Mg-Gd-Y-Zn-Mn alloy is carried out as follows:

Step 1: In a vacuum melting furnace, the ingot is melted, and argon is introduced for protection, and alloying elements are added according to weight percentage Gd=8.4%, Y=5.3%, Zn=1.65%, Mn=0.6%. Among them, Gd, Y, Mn and Zn are respectively added in the form of Mg-30Gd master alloy, Mg-25Y master alloy, Mg-3Mn master alloy and pure Zn.

Insulate at 850°C and stir with electromagnetic induction to fully melt the raw materials. After the alloy is completely melted, continue to stand at 850°C for 10 minutes, and then cast.

Step 2: Homogenize the smelted magnesium alloy ingot, the process parameters are: temperature 540°C±10°C, time 4 hours. After the homogenization treatment, the magnesium alloy ingot was subjected to conventional hot extrusion, the extrusion temperature was 400°C, the extrusion ratio was 11, and the extrusion speed was constant.

The properties of the magnesium alloy are shown in Table 1, where the mechanical properties refer to the tensile strength and yield strength of the alloy at room temperature.

Step 3: Perform aging treatment on the extruded alloy, and its process parameters are: heat treatment temperature is 200° C., holding time is 50 hours, and air cooling. The properties of the magnesium alloy are shown in Table 1, where the mechanical properties refer to the tensile strength and yield strength of the alloy at room temperature. Table 1 is the mechanical property table of the high-strength Mg-Gd-Y-Zn-Mn alloy described in Example 1.

See Table 2 for the formulations of other examples to achieve the purpose of the present invention, wherein the mechanical properties refer to the tensile strength and yield strength of the alloy at room temperature in the aging state; see Example 1 for the process method.

Example 2: A high-strength Mg-Gd-Y-Zn-Mn alloy, alloy composition (weight percent): Gd-9.42%, Y-5.58%, Zn-0.65%, Mn-0.63%, and impurity elements are less than 0.1%, the rest is magnesium.

The manufacturing method of this high-strength Mg-Gd-Y-Zn-Mn alloy is the same as that of Example 1.

Example 3: A high-strength Mg-Gd-Y-Zn-Mn alloy, alloy composition (weight percent): Gd-9.19%, Y-5.6%, Zn-2.82%, Mn-0.72%, and impurity elements are less than 0.1%, the rest is magnesium.

The manufacturing method of this high-strength Mg-Gd-Y-Zn-Mn alloy is the same as that of Example 1.

Embodiment 4: A kind of high-strength Mg-Gd-Y-Zn-Mn alloy, alloy composition (weight percentage): Gd-9.22%, Y-5.59%, Zn-3.74%, Mn-0.56%, impurity element less than 0.1%, the rest is magnesium.

The manufacturing method of this high-strength Mg-Gd-Y-Zn-Mn alloy is the same as that of Example 1.

Example 5: A high-strength Mg-Gd-Y-Zn-Mn alloy, alloy composition (weight percent): Gd-10.01%, Y-5.66%, Zn-1.60%, Mn-0.54%, less impurity elements 0.1%, the rest is magnesium.

The manufacturing method of this high-strength Mg-Gd-Y-Zn-Mn alloy is the same as that of Example 1.

Table 2 is a table of mechanical properties of the high-strength Mg-Gd-Y-Zn-Mn alloy described in Examples 2-5.

The preparation technology adopted in the invention has the advantages of wide versatility, strong portability, simple and mature technology, and easy realization.

It should be pointed out that the above-mentioned embodiments can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way. Therefore, although this specification has described the present invention in detail, those skilled in the art should understand that the present invention can still be modified or equivalently replaced; All should be included in the protection scope of the patent of the present invention.

Claims (4)

1. high strength Mg-Gd-Y-Zn-Mn alloy; It is characterized in that, described magnesium alloy mainly is comprised of Mg, Gd, Y, Zn and Mn, and each moiety quality percentage composition is: Gd=8.2～10.2, and Y=5.0～6.0, Zn=0.5～4.0, Mn=0.5～0.8, surplus is magnesium and inevitable impurity;

Described alloy adopts following method preparation:

(1) calculate according to said components the weight that needs raw material, raw material adopts pure magnesium, industrial-purity zinc, Mg-Gd master alloy, Mg-Y master alloy, Mg-Mn master alloy; Adopt vacuum melting, casting to obtain alloy cast ingot;

(2) alloy cast ingot that step (1) is obtained carries out homogenizing annealing to be processed, and its processing parameter is: 540 ℃ ± 10 ℃ of temperature, 4 hours time; The ingot casting that makes is pushed again and obtain the As-extruded alloy, the processing parameter that wherein adopts is: 400 ℃ ± 10 ℃ of extrusion temperatures, and extrusion ratio is 11, pushes on extrusion machine, extrusion speed is constant;

(3) the As-extruded alloy of step (2) after deformation processing carried out artificial aging and process, its processing parameter is: 200 ℃ of aging temps, and soaking time 50 hours, air cooling makes the high-strength magnesium alloy material.

2. high strength Mg-Gd-Y-Zn-Mn alloy according to claim 1, is characterized in that, in described step (1), described vacuum melting is for to add raw material crucible and to pass into argon gas protection, melting in vacuum smelting furnace; In 850 ℃ of insulations and electromagnetic induction stirring, raw material is fully melted, all continue 850 ℃ of standing insulations 10 minutes after fusing until alloy.

3. high strength Mg-Gd-Y-Zn-Mn alloy according to claim 1, is characterized in that, each moiety quality percentage composition of described magnesium alloy is: Gd-8.4%, Y-5.3%, Zn-1.65%, Mn-0.6%, the total content of impurity＜0.1%; Surplus is magnesium.

4. high strength Mg-Gd-Y-Zn-Mn alloy according to claim 1, is characterized in that, each moiety quality percentage composition of described magnesium alloy is: Gd-10.01%, Y-5.66%, Zn-1.60%, Mn-0.54%, the total content of impurity＜0.1%; Surplus is magnesium.

Images