ALUMINUM ALLOY

Abstract

Disclosed is an aluminum alloy, which is made of a composition including about 0.7˜7.5 wt % of Ti, about 0.2˜1.5 wt % of B and a residue of Al as a main component, wherein the aluminum alloy is formed by melting the composition at about 950˜1000° C.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2012-0143353 filed Dec. 11, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to an aluminum alloy, particularly an aluminum allow whose physical properties are improved by controlling the shape of coarse Al₃Ti contained therein.

2. Description of the Related Art

In conventional aluminum alloys, the amount of Al₃Ti added is restricted because of the shape of Al₃Ti. The reason for this is that the elongation rate of an aluminum alloy is deteriorated because Al₃Ti has a needle shape and is coarsely precipitated.

Al₃Ti, which is formed by the addition of Ti, has a high elastic modulus (270 GPa) and contributes to the improvement of wear resistance of an aluminum alloy. However, when Al₃Ti exists in the shape of a coarse needle, the elongation ratio of an aluminum alloy is greatly deteriorated. Therefore, it is necessary to provide an alloy in which this deterioration of the elongation ratio is minimized.

Japanese Unexamined Patent Application Publication No. 2009-515041 (JP 2009-515041 A) discloses “a crystal fine-grain mother alloy including Ti (1˜10), B (0.2˜2.0) and a residue of Al, wherein the weight ratio of Ti to B is 5˜20”.

However, such alloys are still deficient.

It is to be understood that the foregoing description is provided to merely aid the understanding of the present invention, and does not mean that the present invention falls under the purview of the related art which was already known to those skilled in the art.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to provide an aluminum alloy whose physical properties can be improved by the shape control of coarse Al₃Ti contained therein.

In order to accomplish the above object, an aspect of the present invention provides an aluminum alloy, which is made of a composition including a residue of Al as a main component, about 0.7˜7.5 wt % of Ti, and about 0.2˜1.5 wt % of B. As used herein, reference to Al as a “main component” generally means that the balance of the composition is Al. According to embodiments of the present invention, the aluminum alloy is formed by melting the above composition at about 950˜1000° C.

Another aspect of the present invention provides an aluminum alloy, which is made of a composition including a residue of Al as a main component, about 5˜10 wt % of Ti, and about 0.2˜1.5 wt % of B, wherein a ratio of Ti to B is 3.5˜5.

According to various embodiments, the melting temperature is maintained for about 20˜30 minutes.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 to 3 are photographs showing the change of characteristics of an aluminum alloy due to the addition of Al—Ti,

FIGS. 4 and 5 are photographs showing the improvements of the microtexture of an aluminum alloy due to the addition of B to Al—Ti, according to conventional compositions (FIG. 4) and embodiments of the present invention (FIG. 5); and

FIGS. 6 to 9 are graphs showing the effects of aluminum alloys according to embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about”.

FIGS. 1 to 3 are photographs showing the change of characteristics of an aluminum alloy due to the addition of Al—Ti, FIGS. 4 and 5 are photographs showing the improvements of the microtexture of Al₃Ti due to the addition of B to Al—Ti according to an embodiment of the present invention, and FIGS. 6 to 9 are graphs showing the effects of an aluminum alloy according to an embodiment of the present invention.

The present invention relates to an aluminum alloy whose physical properties can be improved controlling the shape of coarse Al₃Ti contained therein. For this purpose, a component “B” is added, and the melting temperature and melting time of the process are controlled. As a result, the shape of Al₃Ti can be controlled as desired.

According to preferred embodiments, the aluminum alloy of the present invention is made of a composition including about 0.7˜7.5 wt % of Ti, about 0.2˜1.5 wt % of B and a residue of Al as a main component. In particular, the aluminum alloy is formed by melting the composition at about 950˜1000° C. .

Specifically, FIGS. 1 to 3 are photographs showing the change of characteristics of an aluminum alloy due to the addition of Al—Ti. As demonstrated in FIGS. 1 to 3, Al₃Ti increases with an increase of Ti. Further, as demonstrated in Table 1 below, the hardness and strength of an aluminum alloy increases with an increase of Al₃Ti.

TABLE 1
	Phase	Elastic		Yield	Tensile	Elonga-
Compo-	fraction	modulus	Hardness	strength	strength	tion
sition	(wt %)	(GPa)	(HRH)	(MPa)	(MPa)	rate (%)
Al—1Ti	1.47	72.4	27.8	54	83	21
Al—2.3Ti	5	76.2	34.8	60	88	16
Al—5Ti	12.2	80	49.4	70	97	11

However, as further demonstrated in Table 1, while an increase of Al₃Ti results in the noted improvements in the mechanical properties of the aluminum alloy, the elongation rate thereof is decreased.

Therefore, the present invention proposes a method of maintaining the mechanical properties of an aluminum alloy and increasing the elongation rate thereof by controlling the shape of Al₃Ti with the increase of Al₃Ti.

FIGS. 4 and 5 are photographs showing the improvements of the microtexture of Al₃Ti by the addition of B to Al—Ti in accordance with embodiments of the present invention. In particular, the microtexture of Al₃Ti is changed from FIG. 4 to FIG. 5 by the addition of B. That is, FIG. 4 shows the microtexture of Al₃Ti when B was not added (i.e. a conventional composition), and FIG. 5 shows the microtexture of Al₃Ti when B was added in accordance with the composition and process of the present invention.

In this case, with the increase of Ti, Al₃Ti increases, thus increasing the hardness, strength and elastic modulus of an aluminum alloy.

However, with the increase of Ti, the elongation rate of an aluminum alloy will rapidly decrease. Therefore, in the present invention, the hardness, strength, wear resistance and elastic modulus of an aluminum alloy are maintained by the addition of B, and the decrease of elongation rate thereof is prevented by the addition of B.

In accordance with preferred embodiments, in order to effectively increase the strength and elastic modulus of an aluminum alloy, Ti is added in an amount of about 5 wt % or more. However, it has been found that when Ti is added in an amount of about 10 wt % or more, it becomes difficult to control the strength and elastic modulus thereof. Therefore, the amount of Ti added is suitably adjusted to maintain adequate control.

In accordance with preferred embodiments, in order to effectively change the microtexture of Al₃Ti as desired =, B is added in an amount of about 0.2 wt % or more. However, it has been found that when B is added in an amount of about 1.5 wt % or more, it becomes difficult to control the change of the microtexture of Al₃Ti. Therefore, the amount of B added is suitably adjusted to maintain adequate control.

In accordance with preferred embodiments, in order to optimize the effect of improving the microtexture of Al₃Ti, it is preferred that the ratio of Ti to B is about 3.5˜5:1. As set out, the aluminum alloy is formed by melting a composition including Ti, B and a residue of Al. With respect to the melting temperature of the process, it is important to control process temperature because B has a high melting point and is difficult to control. While the process can be carried out to react B with Al₃Ti at 800° C., which is a melting point of Al, such a melting process must be performed for a long time in order to sufficiently change the texture of Al₃Ti because B does not easily react with Al₃Ti at 800° C. However, in this case, a process cost increases.

Therefore, in order to minimize the process cost, the melting process is carried out at a temperature above 800° C., preferably at a melting temperature of about 950˜1000° C., and a molten state is maintained for about 20˜30 minutes. In order to control the shape of Al₃Ti, the shape of Al₃Ti must be changed by reacting B with Al₃Ti. In this case, since the reaction of B with Al₃Ti is caused by diffusion, a melting temperature must be adjusted to about 950° C. or more. However, it has been found that when the melting temperature is higher than about 1000° C., the oxidizability of molten aluminum (Al) undesirably increases. As such, the melting temperature is preferably limited to no greater than about 1000° C.

FIGS. 6 to 9 are graphs showing the effects of aluminum alloys according to embodiments of the present invention. Here, the effects thereof are caused by the addition of B to Al-5Ti by wt %

First, FIG. 6 shows the change in elastic modulus of an aluminum alloy based on the addition of B to Al-5Ti. As shown in FIG. 6, it can be seen that the elastic modulus of an aluminum alloy increases with the increase of the amount of added B.

FIG. 7 shows the change in wear resistance of an aluminum alloy based on the addition of B to Al-5Ti, wherein the wear resistance is a nondimensional relative value. As shown in FIG. 7, it can be seen that the wear resistance of an aluminum alloy increases with the increase of the amount of added B.

FIG. 8 shows the change in hardness of an aluminum alloy based on the addition of B to Al-5Ti. As shown in FIG. 8, it can be seen that the hardness of an aluminum alloy increases with the increase of the amount of added B.

FIG. 9 shows the change in elongation rate of an aluminum alloy based on the addition of B to Al-5Ti. As shown in FIG. 9, it can be seen that the elongation rate of an aluminum alloy increases with the increase of the amount of added B.

Therefore, according to the present invention, B is appropriately added, the ratio of B to Ti is adjusted, and the melting temperature and time in the process are controlled, thus improving the elastic modulus, wear resistance, and particularly elongation rate of an aluminum alloy.

As described above, according to the aluminum alloy of the present invention, the shape of Al₃Ti can be changed by the addition of B and the control of process temperature, thus preventing the deterioration of the elongation rate of the aluminum alloy.

Further, the elastic modulus and wear resistance of the aluminum alloy can be improved by the addition of B and the control of process temperature.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An aluminum alloy, which is made of a composition comprising about 0.7˜7.5 wt % of Ti, about 0.2˜1.5 wt % of B and a residue of Al as a main component, wherein the aluminum alloy is formed by melting the composition at about 950˜1000° C.

2. An aluminum alloy, which is made of a composition comprising about 5˜10 wt % of Ti, about 0.2˜1.5 wt % of B and a residue of Al as a main component, wherein a ratio of Ti to B is about 3.5˜5:1.

3. The aluminum alloy of claim 1, wherein the melting temperature is maintained for about 20˜30 minutes.

4. The aluminum alloy of claim 2, wherein the aluminum alloy is formed by melting the composition at about 950˜1000° C.

5. The aluminum alloy of claim 4, wherein the melting temperature is maintained for about 20˜30 minutes.

6. A method of forming an aluminum alloy comprising:

Providing a composition comprising about 0.7˜7.5 wt % of Ti, about 0.2˜1.5 wt % of B and a residue of Al as a main component; and

melting the composition at about 950˜1000° C.

7. The method of claim 6, wherein a ratio of Ti to B is about 3.5˜5:1.

8. The method of claim 6, wherein the melting temperature is maintained for about 20˜30 minutes.