TWI744075B - Titanium-aluminum intermetallic and method for manufacturing the same for improving casting fluidity - Google Patents

Abstract

A titanium-aluminum intermetallic for improving casting fluidity, calculated in atomic percentage, the titanium-aluminum intermetallic includes the following elements: Al: 40-50 at%, Cr: 1-8 at%, Nb: 1-8 at% , Mo: 1-5 at%, Mn: 1-6 at%, Ni+Si+Fe: 1-15 at% and B: 0.05-0.8 at%, the rest is Ti and unavoidable impurities. The titanium-aluminum intermetallic of the present invention has better casting fluidity, i.e., better castability.

Description

Titanium-aluminum dielectric metal for improving casting fluidity and manufacturing method thereof

The present invention relates to a titanium-aluminum intermetallic and a manufacturing method thereof, and more particularly to a titanium-aluminum intermetallic and a manufacturing method thereof for improving casting fluidity.

Global automobile production is still growing. Due to the requirements for reducing fuel consumption and improving urban air quality, the demand for low-energy high-performance engines is also increasing. Turbochargers can significantly increase engine power, improve emissions, and reduce fuel consumption. The use of small engines with turbochargers to replace naturally aspirated engines is a basic trend in the modern automobile industry. Because turbine blades bear the high temperature and high pressure exhaust gas of the engine, the highest exhaust gas temperature of passenger car diesel engines is about 850°C. The gasoline engine can reach 1050℃. The size of the turbocharger impeller and turbine is not large. Generally, the diameter does not exceed 100mm, but the speed is high, up to 250,000r/min. It can work continuously at high speed under harsh working environment, so it is very important for materials and performance. The requirements are very high, so it is very necessary to develop a high-performance automotive engine rotor and blade material.

Compared with other intermetallic compounds, the overall performance of titanium aluminum (TiAl) intermetallic is good. It has low density, high melting point, high oxidation resistance and excellent high temperature strength and rigidity. At the same time, titanium aluminum intermetallic elasticity The modulus is much higher than other structural materials. As a structural workpiece, it can significantly improve the tolerance of high-frequency vibration. Compared with nickel (Ni)-based alloys, titanium-aluminum intermetallics have higher high-temperature creep resistance and good Flame retardant performance.

However, turbine blades and turbine rotors used in power plants, such as aerospace engine blades, marine generator blades, or vehicle turbine rotors, are mostly thin parts with complex structures. If titanium-aluminum intermetallic is used as the material of the above-mentioned thin parts, it is generally The thin parts can only be produced by using layered manufacturing or post-processing technology, so it has disadvantages such as high manufacturing cost, large material loss, and high processing difficulty. Although attempts have been made to overcome the aforementioned shortcomings by casting technology and directly obtain the complete product morphology, the current limitations of the titanium-aluminum intermetallic material are poor fluidity, which makes the casting difficult to shape, which makes the final casting product poor in properties.

Therefore, there is a need to provide a titanium-aluminum intermetallic for improving casting fluidity and a manufacturing method thereof to solve the aforementioned problems.

One object of the present invention is to provide a titanium-aluminum intermetallic for improving casting fluidity and a manufacturing method thereof, which has better casting fluidity.

According to the above-mentioned purpose, the present invention provides a titanium-aluminum intermetallic for improving casting fluidity. The titanium-aluminum intermetallic includes the following elements: Al: 40-50at%, Cr: 1-8at%, Nb, calculated by atomic percentage : 1~8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.05~0.8at%, the rest is Ti and unavoidable impurities.

The present invention further provides a manufacturing method of titanium-aluminum intermetallic for improving casting fluidity, which includes the following steps: a smelting step: placing a plurality of smelting raw materials of the titanium-aluminum intermetallic in an induction melting device, and smelting these The raw materials are melted into a titanium-aluminum intermetallic broth with casting fluidity; and a casting solidification step: the titanium-aluminum intermetallic broth is cast to solidify into a titanium-aluminum intermetallic, wherein the titanium-aluminum intermetallic is expressed in atomic percentages By calculation, the titanium aluminum intermetallic includes the following elements: Al: 40~50at%, Cr: 1~8at%, Nb: 1~8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+ Fe: 1~15at% and B: 0.05~0.8at%, the rest is Ti and unavoidable impurities.

The titanium-aluminum intermetallic of the present invention has better casting fluidity, that is, better castability.

1: Manufacturing equipment

11: Closed cavity

12: Induction melting device

121: Water-cooled crucible unit

122: induction coil unit

13: Water-cooled mold

14: Vacuum device

15: Nitrogen supply source

16: pipeline unit

17: Measuring Ruler

20: Titanium-aluminum intermetallic molten soup

20’: Titanium-aluminum intermetallic

S1: Step

S2: Step

Figure 1 is an embodiment of the invention for improving the casting fluidity of titanium aluminum intermetallic Flow chart of manufacturing method.

Fig. 2 is a schematic cross-sectional view of a manufacturing equipment of titanium-aluminum intermetallic metal according to an embodiment of the present invention.

Figure 3a is a three-dimensional schematic diagram of the mold for the casting fluidity experiment of the present invention.

Figure 3b is a schematic diagram of the operation of the casting fluidity experiment of the present invention.

Fig. 4 is a schematic diagram of the appearance after casting of the titanium-aluminum intermetallic molten bath of the present invention, which shows the measurement of the length of the spiral flow channel of the titanium-aluminum intermetallic.

In order to make the above objectives, features and characteristics of the present invention more obvious and understandable, the relevant embodiments of the present invention will be described in detail as follows in conjunction with the drawings.

FIG. 1 is a flow chart of a method of manufacturing a titanium-aluminum intermetallic for improving casting fluidity according to an embodiment of the present invention. The manufacturing method of the titanium-aluminum intermetallic of the present invention mainly includes the following steps: (1) Melting step S1: placing a plurality of smelting raw materials of the titanium-aluminum intermetallic in an induction melting device, and melting the smelting raw materials into a casting flow And (2) Casting and solidifying step S2: casting the titanium-aluminum-metallic broth to solidify into a titanium-aluminum-metallic broth.

2 is a schematic cross-sectional view of a manufacturing equipment of titanium aluminum dielectric metal according to an embodiment of the present invention. The titanium-aluminum intermetallic manufacturing equipment 1 includes a closed cavity 11, an induction melting device 12, a water-cooled mold 13, a vacuum device 14 and a protective gas supply source 15. The induction melting device 12 is arranged in the closed cavity 11. The induction melting device 12 includes a water-cooled crucible unit 121 and an induction coil unit 122. The water-cooled crucible unit 121 is used for accommodating a plurality of smelting raw materials. The induction coil unit 122 surrounds the water-cooled crucible unit 121 and is used to inductively heat the smelting raw materials into a titanium-aluminum-metal molten stock 20. The water-cooled mold 13 is arranged in the closed cavity 11 to contain the molten titanium-aluminum-metallic broth 20 after casting. The vacuum device 14 is connected to the closed cavity 11 through a pipeline unit 16 for vacuuming the closed cavity 11. The vacuum device 14 may be a vacuum pump. The shielding gas supply source 15 is connected to the closed cavity 11 through the pipeline unit 16 for supplying shielding gas to the Seal the cavity 11.

For example, the smelting step S1 of the present invention refers to removing titanium (Ti), aluminum (Al), chromium (Cr), niobium (Nb), molybdenum (Mo), manganese (Mn), nickel (Ni) after vacuuming ), silicon (Si), iron (Fe), boron (B) and other smelting materials are placed in the induction melting device 12 for vacuum smelting, so that these smelting materials are melted and mixed into a titanium-aluminum intermetallic broth with a specific ratio 20 . For example, vacuum degree: 10 ^-2 ~10 ^-4 torr, protective gas: 0.3 ~ 0.7Mpa (such as argon or helium). These smelted materials containing Ti, Al, Cr, Nb, Mo, Mn, Ni, Si, Fe, and B include aluminum-niobium alloy, titanium diboride, and pure Cr, Mo, Mn, Ni, Si, and Fe. element. In the smelting step S1, the smelting temperature range is about 1550 to 1650°C, and the temperature holding smelting is performed for 5 to 10 minutes.

8at%，Si

8at%，Fe

8at%。 Furthermore, in the casting and solidification step S2 of the present invention, the titanium-aluminum intermetallic molten stock 20 is cast (the casting temperature is about 1550~1650°C), for example, it is cast into the water-cooled mold 13, and after cooling, it can be solidified into a Titanium-aluminum intermetallic 20', by which the cured titanium-aluminum intermetallic 20 is calculated in atomic percentage, including the following elements: Al: 40~50at%, Cr: 1~8at%, Nb: 1~8at%, Mo : 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.05~0.8at%, the rest is Ti and unavoidable impurities. In detail, after the aforementioned molten material is added to the induction melting device 12 to form a molten alloy, then a sample is taken to measure the atomic composition ratio of the molten alloy in the induction melting device 12 to determine the ratio of the molten mixed titanium-aluminum-metallic broth 20 The composition atomic percentage is maintained at: Al: 40~50at%, Cr: 1~8at%, Nb: 1~8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at % And B: 0.05~0.8at%, the rest is Ti and unavoidable impurities. Under the condition of Ni+Si+Fe: 1~15at%, Ni

8at%, Si

8at%, Fe

8at%.

The addition of chromium (Cr), iron (Fe), manganese (Mn) and nickel (Ni) can lower the alloy liquidus temperature of the titanium-aluminum intermetallic, increase the superheat of the titanium-aluminum intermetallic melt, and slow down the solidification time. Significantly increase the solid-liquid line interval and increase the alloy fluidity. Silicon (Si) on the one hand can improve the oxidation resistance of the alloy, and can reduce the formation of oxide film on the surface of the high-temperature titanium-aluminum-metal molten bath, thereby reducing the surface tension of the titanium-aluminum-metal molten bath and improving the alloy. Gold fluidity; on the other hand, it can reduce the degree of reaction between the titanium-aluminum intermetallic broth and the shell mold, and increase the flow rate of the boundary metal broth. Boron (B) has the effect of grain refinement and is beneficial to improve fluidity, because fine grains will hinder the growth of coarse dendrites, thereby increasing the critical solid phase ratio, thus increasing the flow time and filling length.

Since the casting fluidity of the titanium-aluminum intermetallic is quite complicated, an experimental method must be designed in the casting and solidification step S2 of the present invention to collect effective data collection. Please refer to Figure 3a, which shows the mold for the casting fluidity experiment. Please refer to Figure 3b, which shows a schematic diagram of the casting fluidity experiment. In this embodiment, the mold 30 is a ceramic mold, and the titanium-aluminum intermetallic broth 20 is cast into the mold 30, and the casting fluidity experiment is performed by using the spiral runner of the cast titanium-aluminum intermetallic 20'. The channel size is designed to be length×width (8mm×8mm), and the degree of casting fluidity can be judged by the length of the spiral flow channel, and the effect of the improvement can be known, and compared with the commercial titanium-aluminum intermetallic material (TiAl4822). Please refer to Figure 4, which shows the appearance of the titanium-aluminum intermetallic molten metal after casting, and use the ruler 17 to measure the length of the spiral runner of the titanium-aluminum intermetallic 20' after casting, in order to use the degree of fluidity of the casting Numericalization. The difference in the composition ratio of the titanium-aluminum intermetallic metal and the length of the spiral flow channel between Examples 1 to 4 of the present invention and Comparative Example 11 is shown in Table 1 below:

It can be seen from Table 1 above that the spiral flow of the titanium-aluminum intermetallic in Example 2 The channel length of 73.8 cm is the longest, which represents that the casting fluidity of the titanium-aluminum intermetallic in Example 2 is the best, that is, the casting performance is the best.

In summary, the titanium-aluminum intermetallic of the present invention, calculated in atomic percentage, includes the following elements: Al: 40-50at%, Cr: 1-8at%, Nb: 1-8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.05~0.8at%, the rest is composed of Ti and inevitable impurities, which has better casting fluidity , That is, it has better castability.

To sum up, it only describes the preferred embodiments or examples of the technical means adopted by the present invention to solve the problems, and is not used to limit the scope of the patent implementation of the present invention. That is to say, all changes and modifications that are consistent with the scope of the patent application of the present invention or made in accordance with the scope of the patent of the present invention are all covered by the scope of the patent of the present invention.

S1: Step

S2: Step

Claims (10)

A titanium-aluminum intermetallic used to improve casting fluidity, calculated in atomic percentage, the titanium-aluminum intermetallic includes the following elements: Al: 40-50at%, Cr: 2.211-8at%, Nb: 1-8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.229~0.8at%, the rest is Ti and unavoidable impurities. The titanium-aluminum intermetallic used to improve the casting fluidity as described in the first item of the scope of patent application, wherein under the condition of Ni+Si+Fe:1~15at%, Ni

8at%, Si

8at%, Fe

8at%. A manufacturing method of titanium-aluminum intermetallic for improving casting fluidity, including the following steps: a smelting step: placing a plurality of smelting raw materials of titanium-aluminum intermetallic in an induction melting device, and melting the smelting raw materials into a Casting fluid titanium-aluminum intermetallic broth; and a casting solidification step: casting the titanium-aluminum intermetallic broth to solidify into a titanium-aluminum intermetallic metal, wherein the titanium-aluminum intermetallic metal includes the following calculations in atomic percentages, Al: 40~50at%, Cr: 2.211~8at%, Nb: 1~8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.229~ 0.8at%, the rest is Ti and unavoidable impurities. The manufacturing method of titanium-aluminum intermetallic used to improve casting fluidity as described in item 3 of the scope of patent application, wherein under the condition of Ni+Si+Fe:1~15at%, Ni

8at%, Si

8at%, Fe

8at%. The manufacturing method of titanium-aluminum intermetallic for improving casting fluidity as described in item 3 of the scope of patent application, wherein the smelting temperature in the smelting step ranges from 1550 to 1650°C, and the holding temperature is smelted for 5 to 10 minutes. The manufacturing method of titanium-aluminum intermetallic for improving casting fluidity as described in item 3 of the scope of patent application, wherein the smelting containing Ti, Al, Cr, Nb, Mo, Mn, Ni, Si, Fe and B The materials include aluminum-niobium alloy, titanium diboride and pure elements containing Cr, Mo, Mn, Ni, Si and Fe. As described in item 3 of the scope of patent application, the manufacturing method of titanium-aluminum intermetallic for improving casting fluidity, wherein the casting temperature of the titanium-aluminum intermetallic molten soup is 1550-1650°C. The manufacturing method of titanium-aluminum intermetallic for improving casting fluidity as described in item 3 of the scope of patent application, wherein the casting solidification step includes: a casting fluidity test, and the casting fluidity test is judged by the length of a spiral runner The degree of casting fluidity. The manufacturing method of titanium-aluminum intermetallic for improving casting fluidity as described in item 8 of the scope of patent application, wherein the casting solidification step includes: a casting fluidity experiment, and the casting fluidity experiment measures the length of the spiral runner , Used to quantify the degree of casting fluidity. A titanium-aluminum intermetallic used to improve casting fluidity, calculated in atomic percentage, the titanium-aluminum intermetallic is composed of the following elements: Al: 40-50at%, Cr: 2.211-8at%, Nb: 1-8at%, Mo: 1~5at%, Mn: 1~6at%, Ni+Si+Fe: 1~15at% and B: 0.229~0.8at%, the rest is Ti and unavoidable impurities.

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