ALUMINIUM-TITANIUM-NIOBIUM-BORON INTERMEDIATE ALLOY AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

A preparation method of an AlTiNbB intermediate alloy includes following steps. KBF.sub.4 powder, Nb powder, and Ti powder are ball milled to obtain mixed powder, the mixed powder is pressed to obtain a ball-milled block, an Al block is melted to obtain an Al melt, the ball-milled block is added to the Al melt followed by smelting to obtain alloy liquid, and the alloy liquid is cast to obtain the AlTiNbB intermediate alloy as a refining agent. A high-energy ball milling process is introduced into the preparation method of the AlTiNbB intermediate alloy, improving reaction activity and lowering a reaction threshold. An -Al grain can be refined to be less than 90 m due to uniform dispersion of refining nucleation particles of the refining agent, the refining agent has a great refining effect. The preparation method is simple with easy steps and operations, the AlTiNbB intermediate alloy has high purity.

Claims

1. A preparation method of an aluminium (Al)-titanium (Ti)-niobium (Nb)-boron (B) intermediate alloy, comprising: ball milling potassium tetrafluoroborate (KBF.sub.4) powder, Nb powder, and Ti powder to obtain mixed powder; pressing the mixed powder to obtain a ball-milled block; melting an Al block at 750-800 degree Celsius ( C.) to obtain an Al melt; adding the ball-milled block to the Al melt followed by smelting to obtain alloy liquid; and casting the alloy liquid to obtain the AlTiNbB intermediate alloy; wherein a particle size of the Nb powder is in a range of 30 micrometers (m) to 50 m, and a particle size of the Ti powder is in a range of 1 m to 50 m; wherein a rotation speed in the ball milling is in a range of 200 revolutions per minute (r/min) to 300 r/min, and time of the ball milling is in a range of 4 hours (h) to 6 h; wherein a temperature of the smelting is in a range of 750 C. to 800 C., and time of the smelting is in a range of 20 minutes (min) to 60 min; wherein the AlTiNbB intermediate alloy comprises the following compositions in percentage by weight: Al: 94.9%-96.7%, Ti: 0.5%-1.5%, Nb: 2.5%-4%, B: 0.3%-0.8%; and wherein the AlTiNbB intermediate alloy comprises refined nucleating phases, the refined nucleating phases are (Nb/Ti)Al.sub.3 and (Nb/Ti)B.sub.2, a weight percentage of the refined nucleating phases in the AlTiNbB intermediate alloy is in a range of 1% to 6%, a particle size of the refined nucleating phases is in a range from 1 m to 80 m, and a particle size of the (Nb/Ti)B.sub.2 is not greater than 5 m.

2. The preparation method of the AlTiNbB intermediate alloy as claimed in claim 1, wherein the ball milling is wet milling, a milling medium is anhydrous ethanol, and a ball-to-material ratio is in a range of 5 to 15:1.

3. The preparation method of the AlTiNbB intermediate alloy as claimed in claim 1, wherein the adding the ball-milled block to the Al melt comprises: adding the ball-milled block wrapped in Al foil to the Al melt.

4. The preparation method of the AlTiNbB intermediate alloy as claimed in claim 1, wherein the smelting comprises: stirring the ball-milled block and the Al melt for 0.5-1 min each time at time intervals of 10-20 min.

5-6. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 illustrates an X-ray diffraction (XRD) pattern of an AlTiNbB refining agent according to an embodiment 1 of the disclosure.

[0032] FIG. 2 illustrates a schematic scanning electron microscope (SEM) image of the AlTiNbB refining agent according to the embodiment 1 of the disclosure.

[0033] FIG. 3 illustrates an original grain macrograph of an A356 alloy (a type of AlSi alloy).

[0034] FIG. 4 illustrates a grain macroscopic morphology of the A356 alloy added with the AlTiNbB refining agent according to the embodiment 1 of the disclosure.

[0035] FIG. 5 illustrates an XRD pattern of an AlTiNbB refining agent according to an embodiment 2 of the disclosure.

[0036] FIG. 6 illustrates a SEM image of the AlTiNbB refining agent according to the embodiment 2 of the disclosure.

[0037] FIG. 7 illustrates a grain macroscopic morphology of an A356 alloy added with the AlTiNbB refining agent according to the embodiment 2 of the disclosure.

[0038] FIG. 8 illustrates an XRD pattern of an AlTiNbB refining agent according to an embodiment 3 of the disclosure.

[0039] FIG. 9 illustrates a SEM image of the AlTiNbB refining agent according to the embodiment 3 of the disclosure.

[0040] FIG. 10 illustrates a grain macroscopic morphology of an A356 alloy added with the AlTiNbB refining agent according to the embodiment 3 of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0041] In order to make the purpose, technical solution, and effects of the disclosure clearer, detailed explanations of the disclosure are further provided below in conjunction with embodiments. The specific embodiments described here are only intended to explain the disclosure and are not intended to limit the disclosure.

[0042] Raw materials selected for the embodiments below are: a 356 alloy (a type of AlSi alloy), KBF.sub.4 powder (99.95%), Ti powder (99.98%), Nb powder (99.98%) and commercially pure Al.

Embodiment 1

[0043] A preparation method of an AlTiNbB refining agent of the embodiment 1

[0044] The AlTiNbB refining agent includes the following compositions in percentage by weight: Ti: 1.0 weight percentage (wt. %), Nb: 3.0 wt. %, B: 0.5 wt. %, unavoidable impurity content less than 0.1 wt. %, and the rest is Al. The raw materials are weighed according to the compositions of the AlTiNbB refining agent.

[0045] A preparation process of the AlTiNbB refining agent includes following steps.

[0046] (1) High energy ball milling of the raw materials: the Ti powder, the Nb powder, and the KBF4 powder are mixed in proportion to obtain mixed powder, the mixed powder is placed in a stainless-steel ball milling tank (which is washed and dried in advance), and added with stainless-steel beads with a ball-to-material ratio of 10:1, and then anhydrous ethanol as a ball milling medium is added to the stainless-steel ball milling tank to slightly submerge the mixed powder and balls (i.e., the stainless-steel beads). Then, the stainless-steel ball milling tank is vacuumed for 30 seconds to obtain a vacuumed tank, the vacuumed tank is filled with protective gas argon. Operations of vacuuming and filling with the protective gas argon are repeated three times to obtain a processed tank to ensure that air in the processed tank is completely discharged and avoid oxidation of metal raw material powder during a ball milling process. The processed tank is placed in a planetary ball mill with a rotation speed of 300 r/min for ball milling for 6 h.

[0047] After ball milling, the mixed powder in the processed tank is dried and compacted to obtain a ball-milled block for future use.

[0048] (2) Smelting of an AlTiNbB alloy (the AlTiNbB refining agent): the commercially pure Al is placed in a graphite clay crucible and heated to a temperature of 750 C. in a box-type high-temperature furnace followed by keeping the temperature unchanged for a period to obtain an Al melt, the ball-milled block is wrapped with Al foil and then is pressed into the Al melt to obtain a mixed melt, the mixed melt is stirred for half a minute and then is placed in the box-type high-temperature furnace for keeping the temperature unchanged for 40 min. During the 40 min, the mixed melt is thoroughly stirred by a graphite stirring rod for 0.5-1 min at intervals of 20 min. After the 40 min, floating slag on a surface of the mixed melt is removed, and then the mixed melt is stirred thoroughly to obtain alloy liquid, the alloy liquid is cast into a cast iron mold followed by solidification to obtain the AlTiNbB alloy, denoted as an Al-3Nb-1Ti-0.5B-750 C. refining agent.

Experimental Testing Analysis:

[0049] In order to characterize the compositions of the AlTiNbB refining agent prepared in the embodiment 1, XRD analysis is performed on the Al-3Nb-1Ti-0.5B-750 C. refining agent prepared in the embodiment 1. As shown in FIG. 1, a phase composition of the Al-3Nb-1Ti-0.5B-750 C. refining agent is -Al, (Nb/Ti) Al.sub.3, and (Nb/Ti) B.sub.2 phases.

[0050] In order to observe a microstructure of the AlTiNbB refining agent, the Al-3Nb-1Ti-0.5B-750 C. refining agent prepared in the embodiment 1 is characterized by scanning electron microscopy. As shown in FIG. 2, a structure of the Al-3Nb-1Ti-0.5B-750 C. refining agent is uniform, and a grain size of a refined nucleation point (Nb/Ti) Al.sub.3 is less than 10 m, a grain size of (Nb/Ti) B.sub.2 is less than 2 m, and both the (Nb/Ti) Al.sub.3 and the (Nb/Ti) B.sub.2 are dispersed in small pieces on a matrix.

[0051] A method for refining the AlSi alloy by the Al-3Nb-1Ti-0.5B-750 C. refining agent includes following steps.

[0052] The A356 alloy is placed in a graphite clay crucible and heated to a temperature of 730 C. in a well furnace to obtain an AlSi melt, the AlSi melt is added with the Al-3Nb-1Ti-0.5B-750 C. refining agent followed by keeping the temperature unchanged for 5 min to obtain a mixture, a refining agent amount is based on 0.09% Nb of a total weight of the mixture, the mixture is cast into a graphite disc mold to obtain a refined A356 alloy ingot (i.e., a refined A356 alloy).

[0053] FIG. 3 illustrates an original grain macrograph of the A356 alloy, an average grain size reaches greater than 1569 m. FIG. 4 illustrates a grain macroscopic morphology of the refined A356 alloy which is refined by the AlTiNbB refining agent prepared in the embodiment, a grain size of the refined A356 alloy is reduced to be less than 90 m.

Embodiment 2

[0054] The embodiment 2 is basically the same as the embodiment 1, with special features below.

[0055] Smelting of an AlTiNbB alloy (the AlTiNbB refining agent): the commercially pure Al is placed in a graphite clay crucible and heated to a temperature of 750 C. in a box-type high-temperature furnace followed by keeping the temperature unchanged for a period to obtain an Al melt, the ball-milled block is wrapped with Al foil and then is pressed into the Al melt to obtain a mixed melt, the mixed melt is stirred for half a minute and then is placed in the box-type high-temperature furnace for keeping the temperature unchanged for 60 min. During the 60 min, the mixed melt is thoroughly stirred by a graphite stirring rod for 0.5-1 min at intervals of 20 min. After the 60 min, floating slag on a surface of the mixed melt is removed, and then the mixed melt is stirred thoroughly to obtain alloy liquid, the alloy liquid is cast into a cast iron mold followed by solidification to obtain the AlTiNbB alloy, denoted as an Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent.

[0056] A method for refining the AlSi alloy by the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent includes following steps.

[0057] The A356 alloy is placed in a graphite clay crucible and heated to a temperature of 730 C. in a well furnace to obtain an AlSi melt, the AlSi melt is added with the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent followed by keeping the temperature unchanged for 5 min to obtain a mixture, a refining agent amount is based on 0.09% Nb of a total weight of the mixture, the mixture is cast into a graphite disc mold to obtain a refined A356 alloy ingot (i.e., a refined A356 alloy).

Experimental Testing Analysis:

[0058] In order to characterize the compositions of the AlTiNbB refining agent prepared in the embodiment 2, XRD analysis is performed on the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent prepared in the embodiment 2. As shown in FIG. 5, a phase composition of the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent is -Al, (Nb/Ti) Al.sub.3, and (Nb/Ti) B.sub.2 phases.

[0059] In order to observe a microstructure of the AlTiNbB refining agent, the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent prepared in the embodiment 2 is characterized by scanning electron microscopy. As shown in FIG. 6, a structure of the Al-3Nb-1Ti-0.5B-750 C.-60 min refining agent is uniform, and a grain size of a refined nucleation point (Nb/Ti) Al.sub.3 is less than 20 m, a grain size of (Nb/Ti) B.sub.2 is less than 5 m, and both the (Nb/Ti) Al.sub.3 and the (Nb/Ti) B.sub.2 are dispersed in small pieces on a matrix.

[0060] FIG. 7 illustrates a grain macroscopic morphology of the refined A356 alloy refined by the AlTiNbB refining agent prepared in the embodiment 2, a grain size of the refined A356 alloy is reduced to be less than 100 m.

Embodiment 3

[0061] The embodiment 3 is basically the same as the embodiment 1, with special features below.

[0062] Smelting of an AlTiNbB alloy (the AlTiNbB refining agent): the commercially pure Al is placed in a graphite clay crucible and heated to a temperature of 850 C. in a box-type high-temperature furnace followed by keeping the temperature unchanged for a period to obtain an Al melt, the ball-milled block is wrapped with Al foil and then is pressed into the Al melt to obtain a mixed melt, the mixed melt is stirred for half a minute and then is placed in the box-type high-temperature furnace for keeping the temperature unchanged for 40 min. During the 40 min, the mixed melt is thoroughly stirred by a graphite stirring rod for 0.5-1 min at intervals of 20 min. After the 40 min, floating slag on a surface of the mixed melt is removed, and then the mixed melt is stirred thoroughly to obtain alloy liquid, the alloy liquid is cast into a cast iron mold followed by solidification to obtain the AlTiNbB alloy, denoted as an Al-3Nb-1Ti-0.5B-850 C. refining agent.

[0063] A method for refining the AlSi alloy by the Al-3Nb-1Ti-0.5B-850 C. refining agent includes following steps.

[0064] The A356 alloy is placed in a graphite clay crucible and heated to a temperature of 730 C. in a well furnace to obtain an AlSi melt, the AlSi melt is added with the Al-3Nb-1Ti-0.5B-850 C. refining agent followed by keeping the temperature unchanged for 5 min to obtain a mixture, a refining agent amount is based on 0.09% Nb of a total weight of the mixture, the mixture is cast into a graphite disc mold to obtain a refined A356 alloy ingot (i.e., a refined A356 alloy).

Experimental Testing Analysis:

[0065] In order to characterize the compositions of the AlTiNbB refining agent prepared in the embodiment 3, XRD analysis is performed on the Al-3Nb-1Ti-0.5B-850 C. refining agent prepared in the embodiment 3. As shown in FIG. 8, a phase composition of the Al-3Nb-1Ti-0.5B-850 C. refining agent is -Al, (Nb/Ti) Al.sub.3, and (Nb/Ti) B.sub.2 phases.

[0066] In order to observe a microstructure of the AlTiNbB refining agent, the Al-3Nb-1Ti-0.5B-850 C. refining agent prepared in the embodiment 3 is characterized by scanning electron microscopy. As shown in FIG. 9, a structure of the Al-3Nb-1Ti-0.5B-850 C. refining agent is uniform, and a grain size of a refined nucleation point (Nb/Ti) Al.sub.3 is less than 15 m, a grain size of (Nb/Ti) B.sub.2 is less than 6 m, and both the (Nb/Ti) Al.sub.3 and the (Nb/Ti) B.sub.2 are dispersed in small pieces on a matrix.

[0067] FIG. 10 illustrates a grain macroscopic morphology of the refined A356 alloy refined by the AlTiNbB refining agent prepared in the embodiment 3, a grain size of the refined A356 alloy is reduced to be less than 200 m.

Comparative Embodiment 1

[0068] The comparative embodiment 1 is basically the same as the embodiment 1, with special features below: the raw material powder (i.e., the mixed powder) is not ball milled by the planetary ball mill, while other operations are same. A raw material absorption rate of an AlTiNbB alloy prepared in the comparative embodiment 1 significantly decreases, and there are residues on an inner wall and a bottom of the graphite clay crucible that do not react. The number of refined nucleating phases generated decreases, and a grain size of a refined A356 alloy is greater than 300 m, which is far inferior to a refining effect of the embodiment 1.

[0069] The embodiments described in the disclosure only describe preferred embodiments of the disclosure, and do not limit the concept and scope of the disclosure. Without departing from the design concept of the disclosure, all variations and modifications made by those skilled in the art to the technical solution of the disclosure should fall within the scope of protection of the disclosure.