JPH0344441A - Formed body of aluminum alloy with high strength and heat resistance and its production - Google Patents

Abstract

PURPOSE:To improve heat resistance and to provide high strength by blending specific amounts of Fe powder with an Al (alloy) powder, forming an amorphous region in a part of the resulting powder mixture by means of mechanical alloying treatment, and then carrying out solidification and forming. CONSTITUTION:An Fe powder is blended by 1-10wt.% with an Al or Al alloy powder. The resulting powder mixture is subjected to mechanical alloying treatment by using a ball mill, an attritor, etc., by which an amorphous region is formed in a part of the powder mixture. Subsequently, solidification and forming are performed and the amorphous part is decomposed and formed into a refined structure, by which a formed body in which an Al-base fine structure is stuck by means of the finely dispersed grains of Fe can be obtained. By this method, a heat resisting Al alloy showing excellent strength both at ordinary temp. and at high temp. can be produced while obviating the necessity of the use of SiC, alumina fiber, etc.

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention relates to an aluminum alloy molded body used in high-temperature environments and a method for manufacturing the same, and in particular, it relates to aluminum alloy molded bodies used in high-temperature environments, and in particular, to high-strength and heat-resistant molded bodies such as those used in internal combustion engines. The present invention relates to an aluminum alloy molded body used in the field of mechanical structural materials requiring the following, and a method for manufacturing the same.

[Prior Art] Al and Al alloys are lightweight, heat resistant, and have excellent strength at room temperature, and are prized as basic materials in a wide range of fields.

However, it has the disadvantage of low high-temperature strength, so the required performance has become even more stringent when applied to internal combustion engines such as automobiles, and various electrical products and mechanical products used in relatively high-temperature environments. Partly because it's on display, it hasn't come to the point where it's being used.

For example, even with Al-Cu alloys, which are said to have relatively excellent high-temperature strength among Al alloys, At-Cu precipitates, which are hardened particles, become coarse in high-temperature environments exceeding 200°C. It was thought that there was a limit to its application to applications requiring heat resistance, as this would lead to a decrease in strength.

In contrast, Al-based composite materials that use SiC whiskers and alumina fibers as reinforcing materials are attracting attention, and expanding the use of Al alloys is being considered.
However, it has not been possible to expand the range of practical use due to the fact that it remains thermally weak and that it is expensive.

In addition, it has been studied to obtain a rapidly solidified aluminum powder alloy by alloying large amounts of transition metal elements such as Fe and Cr, and it has been reported that it is effective in improving heat resistance and wear resistance.
However, supersaturated elements such as Fe, which have been made into a solid solution by rapid cooling, form intermetallic compounds during the solidification process of the powder alloy or during use in high-temperature environments, resulting in the formation of coarse particles. It was found that this resulted in a decrease in strength, and the effect of improving heat resistance was ultimately very insufficient.

[Problems to be Solved by the Invention] The present invention is concerned with the development of the prior art as described above, and aims to provide a high-strength, heat-resistant aluminum alloy molded body. Focusing on the mobility of dislocations at high temperatures, which is considered to be the governing factor for heat resistance, we attempted to introduce a microstructure that would prevent the generation and rearrangement of dislocations as a group. In addition, in order to ensure economic efficiency, we decided to avoid the use of expensive ceramics and instead use metal powder that is relatively inexpensive and can be made by hand.

[Means for Solving the Problems] The high-strength, heat-resistant aluminum alloy molded body provided by the present invention is one in which 1 to 10% by weight of Fe is blended into AI or Al alloy, and the microstructure of the Al group is composed of Fe microstructure. It is fixed by dispersed particles. In addition, as a specific means for manufacturing such a compact, 1 to 10% by weight of Fe powder is blended with Al or Al alloy powder, and a part of the mixed powder is amorphous by mechanical alloying treatment. form a quality area,
A method of solidifying the same is then provided.

[Function] The aluminum alloy molded body according to the present invention has a fine structure formed in aluminum serving as a base, and this fine structure is fixed by finely dispersed particles of Fe,
Although there are no particular restrictions on the manufacturing method,
The method that the present inventors recommend as an excellent means is as follows.

The main raw material is an AI or Al alloy powder that may contain some impurities (inevitable elements or oxides), and 1 to 10% by weight of Fe powder is mixed therein. It is permissible for the Fe powder to contain a small amount of the same impurities as mentioned above. Mechanical alloying is achieved by processing this mixed metal powder with a pulverizer such as a ball mill or an attriter, or a mixer or a stirrer capable of applying a large amount of mechanical energy. In other words, mechanical energy is applied to partially amorphize the base aluminum, and this amorphous portion is decomposed in the subsequent solidification molding process to form a fine structure.

The total time required for the mechanical alloying process may be adjusted as appropriate by determining the amount of metal powder mixture used as a raw material and the degree of mechanical energy. If a part of the base aluminum is made amorphous in this way, the amorphous region will decompose under the pressure and temperature conditions during solidification and molding of this mixed powder, and the resulting microstructure will be heated up. It is fixed by physically stable finely dispersed particles. If such a characteristic structure is formed, the rearrangement of dislocations will not occur even at high temperatures of 400°C or higher, which is considered the recrystallization softening temperature of conventional Al alloys, and the high-temperature strength will be improved in a distant manner. be done. Although the means of solidification molding mentioned above does not limit the scope of the present invention, typical methods include, for example, molding made of AI or A
Examples include a method of filling a mixed powder into a capsule made of L alloy, degassing the inside of the capsule, and then molding the capsule using a HIP method or an extrusion method.

The blending amount of Fe powder in the present invention must be 1 to 10% by weight; if it is less than 1% by weight, the effect of fixing the fine structure is insufficient, and if it exceeds 10ffifc%, coarse Fe particles are likely to be formed. On the contrary, there is a danger that the high-temperature strength will deteriorate.

[Example] Commercially available aluminum powder obtained by real IL air atomization method was
．． 5 to 20% water atomized iron powder was added, and mechanical alloying was performed for 20 hours using an attritor. The obtained mixed powder was filled into an Al alloy capsule, vacuum degassed, heated in a salt bath at 400°C, and immediately subjected to hot isostatic extrusion (extrusion ratio = 10) to form a 12 φ I got a round bar. When we measured the high temperature strength of each round bar, we found that
The results shown in the table were obtained.

No. table H.

a: Vickers hardness (kg10n'): Tensile strength (kg/mm') As shown in Table 1, those that satisfy the conditions of the present invention have a Vickers hardness of 150 kg/mm2 or more at room temperature.
The Vickers hardness at 300° C. exceeds 100 kg/mm 2 .

4% by weight of water atomized iron powder was added to pure Al powder obtained by the Gooyugas atomization method, and mechanical alloying was performed using an attritor. Experiments were conducted by changing the mechanical alloying treatment time, and the relationship between the microstructure of the obtained alloy powder and the mechanical strength after solidification and forming shown in Table 1 of Example 1 was examined, and Table 2 shows It was as follows.

Amorphous surface: Confirmed by Mössbauer analysis As shown in Table 2, amorphous regions are observed in the solidified compacts that have been subjected to sufficient mechanical alloying IA process, and are not only resistant at room temperature but also at high temperatures. Good strength was also obtained.

[Effects of the Invention] Since the present invention is configured as described above, a high-strength, heat-resistant aluminum alloy that exhibits excellent strength at both room temperature and high temperature is provided. In this case, there is no need to use expensive ceramics such as SiC or Al-based fibers, so the economical efficiency can also be fully satisfied.

Claims (2)

[Claims] (1) A high-strength, heat-resistant aluminum alloy molded article, characterized in that 1 to 10% by weight of Fe is blended with Al or an Al alloy, and the Al-based microstructure is fixed by finely dispersed particles of Fe. (2) Mixing 1 to 10% by weight of Fe powder with Al or Al alloy powder, performing mechanical alloying treatment to form an amorphous region in a part of the mixed powder, and then solidifying and molding this. A method for producing a high-strength, heat-resistant aluminum alloy molded body according to claim (1).