JPH055147A - Low thermal expansion aluminum alloy excellent in wear resistance - Google Patents

Abstract

PURPOSE:To provide a low thermal expansion aluminum alloy excellent in wear resistance and reduced in coefficient of thermal expansion. CONSTITUTION:The alloy has a composition consisting of, by weight, 10-12% Si, 2-4% Cu, 0.3-2% Mg, 8-10% Ni, and the balance aluminum with inevitable impurities. Further, the average grain size of Al-Ni intermetallic compounds dispersed in the alloy is regulated to 5-30mum and the average grain size of Si is regulated to 2-20mum. If necessary, one or >=2 elements among Fe, Cr, Mn, Zr, Zn, Na, Sr, and Sb can be incorporated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear resistance suitable for use in pistons and other automobile sliding parts, various machine parts, etc., which require a small coefficient of thermal expansion and excellent wear resistance and elastic modulus. Relates to a low thermal expansion aluminum alloy having excellent heat resistance.

[0002]

2. Description of the Related Art Heretofore, as this type of aluminum alloy, an Al--Si alloy containing Si as an element for improving wear resistance has been well known, and is generally widely used. ..

[0003]

However, when the amount of Si added is increased to improve the wear resistance, the wear resistance is improved and the thermal expansion coefficient is decreased, but the castability, machinability, etc. are decreased. However, there is a problem in that the amount added is naturally limited.

In view of the above circumstances, the present invention has an object to provide an aluminum alloy which is excellent in mechanical properties such as wear resistance, elastic modulus and strength, and also excellent in physical properties such as thermal expansion. It was made.

[0005]

[Means for Solving the Problems] The above object is Si: 10.
~ 12 wt%, Cu: 2-4 wt%, Mg: 0.3-2 wt%
%, Ni: 8-10 wt%, or F
e: 0.05 to 0.5 wt%, Cr: 0.01 to 0.5 wt
%, Mn: 0.01 to 1.0 wt%, Zr: 0.01 to
0.5 wt%, Zn: 0.1-1.0 wt%, Na: 0.0
05-0.1wt%, Sr: 0.0005-0.02wt
%, Sb: 0.01 to 0.5 wt% of 1 type or 2 types or more, the average particle diameter of the Al-Ni-based intermetallic compound which is dispersed in the alloy and is composed of the balance aluminum and inevitable impurities. Is 5 to 30 μm, and the average particle size of Si is 2 to 20 μm.

First, the significance of addition of each element in the alloy of the present invention and the reason for limiting the composition range will be described. Si (silicon) is an element that contributes to improvement of wear resistance and strength, and also to low thermal expansion. is there. However, if its content is less than 10 wt%, its effect is poor. On the contrary, even if it exceeds 12 wt%, not only the above-mentioned effect is not particularly enhanced but also the workability is deteriorated. Therefore, Si is 10 to 1
It must be contained in the range of 2 wt%. A particularly preferred Si content range is 10.5-11.5 wt%.

Both Cu (copper) and Mg (magnesium) contribute to improving the strength of the alloy. However, Cu is 2 wt%
If the Mg content is less than 0.3 wt%, the effect is poor. On the contrary, if the Cu content exceeds 4 wt% or the Mg content exceeds 2 wt%, the workability is deteriorated. Therefore, Cu must be contained in the range of 2 to 4 wt% and Mg in the range of 0.3 to 2 wt%. C
A particularly preferable content range of u and Mg is Cu: 2.5 to 3.
8 wt% and Mg: 0.5 to 1.8 wt%.

[0008] Ni (nickel) is dispersed in the alloy matrix as an Al-Ni intermetallic compound such as Al ₃ Ni and mainly contributes to improvement of wear resistance, elastic modulus and reduction of thermal expansion coefficient. However, if it is less than 8 wt%, it is difficult to disperse a sufficient amount of the intermetallic compound, and the effect of improving the wear resistance is poor. On the other hand, 1
When it is contained in an amount of more than 0 wt%, the extrudability is lowered and the ductility is lowered. Therefore, Ni is 8-10 wt%
Must be contained within the range. Particularly preferred Ni
The content range of is about 8.5 to 9.5 wt%.

In the present invention, as an optional component, Fe (iron):
0.05-0.5 wt%, Cr (chrome): 0.01-
0.5 wt%, Mn (manganese): 0.01 to 1.0 wt
%, Zr (zirconium): 0.01 to 0.5 wt%, Z
n (zinc): 0.1 to 1.0 wt%, Na (sodium): 0.005 to 0.1 wt%, Sr (strontium): 0.0005 to 0.02 wt%, Sb (antimony): 0.01 The inclusion of one or more of 0.5 wt% is acceptable. All of these are effective in improving the mechanical properties of the alloy. More specifically,
Fe, Cr, Mn, and Zr are all effective elements for grain refinement of the alloy, but Fe is less than 0.05 wt%, Cr,
If Mn and Zr are less than 0.01 wt%, the effect is poor,
Conversely, Fe, Cr, and Zr exceed 0.5 wt% and Mn is 1.
Even if it exceeds 0 wt%, no significant increase in the effect can be obtained and it is substantially wasted. A particularly preferable content range is Fe: 0.
1 to 0.45 wt%, Cr: 0.05 to 0.3 wt%, M
n: 0.05-0.8wt%, Zr: 0.05-0.3wt
%.

Zn contributes to the strength improvement of the alloy, but if it is less than 0.1 wt%, its effect is poor, and conversely 1.
Even if the content exceeds 0 wt%, the effect is saturated. Zn
A particularly preferable content range of is 0.2 to 0.8 wt%.

Na, Sr, and Sb have the effect of refining the Si particles and thus improving the mechanical properties of the alloy. However, Na is less than 0.005 wt% and Sr is 0.0005.
If it is less than wt% and Sb is less than 0.01 wt%, the effect is poor. On the other hand, Na exceeds 0.1 wt% and Sr is 0.02 wt%
%, And even if Sb is contained in excess of 0.5 wt%, the effect is saturated and substantial waste is caused. A particularly preferred content range is Na: 0.008 to 0.05 wt%, Sr: 0.00
5 to 0.015 wt% and Sb: 0.05 to 0.3 wt%.

By the way, according to the present invention, in order to achieve desired wear resistance, it is necessary that the Si particles and the Al—Ni intermetallic compound are simultaneously dispersed in the alloy. As a result, in addition to the effect of improving the wear resistance by the Si particles, the effect of improving the wear resistance by the Al-Ni-based intermetallic compound such as hard Al ₃ Ni acts synergistically,
As a result, excellent wear resistance can be exhibited. For this purpose, the average particle size of the Al-Ni intermetallic compound is 5 to 30 μm, and the average particle size of Si is 2 to 20 μm.
It must be specified in the range of m. If the average particle size of the Al—Ni intermetallic compound is less than 5 μm and the average particle size of Si is less than 2 μm, sufficient effect of improving wear resistance cannot be obtained. On the other hand, the average particle size of the Al-Ni intermetallic compound exceeds 30 μm, or the average particle size of Si is 20 μm.
When it exceeds, the workability such as machinability is adversely affected. Particularly preferably, the average particle size of the Al-Ni intermetallic compound is 10
˜25 μm, and the average particle diameter of Si is preferably 3 to 8 μm.

The present invention is specified by the composition of the alloy, the Al-Ni based intermetallic compound and the average particle size of Si, and the manufacturing method for realizing such a textured state is not limited thereto. It may be manufactured through a melting / casting process. Further, the control of the average particle diameter of the Al-Ni-based intermetallic compound and Si can be performed, for example, by controlling the cooling rate during ingot production. In addition, it is desirable to manufacture it as an extruded material that has been subjected to a hot extrusion process. The reason for this is that it is possible to expect an effect of improving the mechanical properties by refining the intermetallic compound and improving the dispersion state by hot working.

[0014]

[Examples] Aluminum alloy ingots having various compositions shown in Table 1 were produced by die casting (3 ^〃φ ).

[0015]

[Table 1]

Each of the above aluminum alloy ingots was 460
After extruding into a 12 mmφ round bar in the heat of ℃, 490
A sample treatment was carried out by sequentially carrying out a solubilization treatment at ℃ × 3 hours and an aging treatment at 180 ℃ × 7 hours. And the average particle diameter of Si and Al-Ni type | system | group intermetallic compound in each test material was measured. The results are shown in Table 1.

The wear resistance, coefficient of thermal expansion, and mechanical properties of each of the above test materials were also investigated. The results are shown in Table 2.

The abrasion resistance was tested by using a dry Ogoshi type abrasion tester under the conditions of final load 2.1 kg, friction distance 600 m, friction speed 3.67 m / sec, and mating material FC30. It was evaluated by measuring the specific wear amount of the material.

[0019]

[Table 2]

As can be seen from the results in Table 2 above, the products of the present invention (samples Nos. 1 to 10) have the same S content as compared with the comparative products (Nos. 11 and 12) having an alloy composition deviating from the present invention.
It was confirmed that even though it contained i, it was further excellent in wear resistance, had a small coefficient of thermal expansion, and had excellent mechanical properties.

[0021]

Since the present invention is as described above, it can be made into an aluminum alloy having excellent wear resistance and low thermal expansion and can be suitably used as a material for automobile sliding parts and various machine parts. it can.

Claims (1)

Claims: Si: 10 to 12 wt%, Cu: 2 to 4 wt%
%, Mg: 0.3 to 2 wt%, Ni: 8 to 10 wt%, the balance of aluminum and unavoidable impurities, and the average particle size of the Al-Ni intermetallic compound dispersed in the alloy is 5 ˜30 μm, and the average particle size of Si is 2˜2.
A low thermal expansion aluminum alloy having excellent wear resistance characterized by having a thickness of 20 μm. 2. Si: 10 to 12 wt%, Cu: 2 to 4 wt%
%, Mg: 0.3-2 wt%, Ni: 8-10 wt%, Fe: 0.05-0.5 wt%, Cr: 0.0
1-0.5 wt%, Mn: 0.01-1.0 wt%, Zr:
0.01-0.5 wt%, Zn: 0.1-1.0 wt%, N
a: 0.005-0.1 wt%, Sr: 0.0005-
Al-Ni based intermetallic compound containing 0.02 wt% and Sb: 0.01 to 0.5 wt% of one kind or two or more kinds, consisting of the balance aluminum and unavoidable impurities and dispersed in the alloy. A low thermal expansion aluminum alloy having excellent wear resistance, which has an average particle size of 5 to 30 μm and an average particle size of Si of 2 to 20 μm.