JPS59208040A - Dispersion strengthened eutectic aluminum alloy - Google Patents

Abstract

PURPOSE:To obtain an alloy having high wear resistance and strength by dispersing fine particles for strengthening to be dispersed in Al matrix into fine dendrite as well and specifying the size of the dendrite as well as the grain size, intergranular distance and volume ratio of said fine particles. CONSTITUTION:The size of dendrite is more preferable as the size is smaller and is made <=20mu. Fine particles for strengthening are the oxide, carbide, nitride, etc. of Si, etc. which exist stably in Al matrix at a high temp. without growing to or forming coarse grains, and the grain size thereof is made <=0.5mu in order to obtain substantial dispersion strengthening. The intergranular distance of the fine grains is more preferable as the size is smaller and is made <=30mu. The larger the amt. of the fine particles, the better but if the amt. exceeds 20% by weight, substantial dispersion strenghtening cannot be obtained and mixed dispersion is difficult and therefore 20% is the upper limit. The fine particles for strengthening are uniformly dispersed in a molten eutectic Al alloy and thereafter pressurized and cooled quickly to satisfy the above-mentioned conditions, by which the intended alloy is obtd.

Description

[Detailed description of the invention] The present invention relates to dispersion strengthened eutectic aluminum alloys.

Dispersion-strengthened alloys in which hard, fine particles that are stable even at high temperatures are dispersed and composited in a metal matrix are known. For example, if the matrix is aluminum, S A
P
wder) is well known. The strength of this dispersion-strengthened alloy improves as the amount of dispersed fine particles increases and as the particle spacing becomes narrower.

On the other hand, it is well known that dendrites are crystallized in eutectic aluminum alloys (hereinafter abbreviated as eutectic 81 alloys), and the shape and size of these dendrites affect the strength of the alloy.

However, in conventional dispersion-strengthened alloys, the particle size of reinforcing particles is generally large, and sufficient strength and wear resistance have not been achieved.

In particular, when the eutectic 81 alloy is strengthened by dispersing reinforcing fine particles, the fine particles gather at the interface between the dendrite and the aluminum matrix and do not enter the dendrite, making it difficult to obtain sufficient strength. was difficult.

The present invention was made in order to solve the problems of the above-mentioned prior art, and an object of the present invention is to provide a dispersion-strengthened eutectic AI alloy having excellent strength and toughness.

According to the eutectic^1 alloy of the present invention, this purpose is achieved by dispersing reinforcing fine particles in the aluminum matrix,
This is achieved by dispersing these fine particles even into fine dendrites. Here, the size of the dendrite is 20μ or less, and the particle size of the reinforcing fine particles is 0.5μ.
μ or less, interparticle distance 30 μ or less, and volume ratio 20% or less. In this way, the dendrites are made finer, and because the reinforcing fine particles are fine and also dispersed in the dendrites, the dispersion strengthening of the reinforcing fine particles functions effectively, and the movement of dislocations is prevented. This significantly increases the strength of the eutectic A1 alloy.

Next, the present invention will be explained in detail.

In the present invention, the smaller the size of the dendrite, the better the strength and toughness, so it is preferable that the size of the dendrite is at least 20 μm or less. Further, it is more desirable that the thickness be 18μ or less.

The reinforcing fine particles must stably exist in the aluminum matrix at high temperatures and do not grow or coarsen, which would cause a decrease in strength.

Fine particles meeting this condition include oxides, carbides, nitrides, and the like. Specifically, 5iC1"T' i C1Z
rC, WC, NbC,, TiNXBN, St, N4, A
l2O, Mg0s Sin, ZrO2, Fe 20
s, CuO1 graphite, etc. can be used.

The particle size of these fine particles must be 0 to obtain sufficient dispersion strengthening.
．． It is necessary that it is 5 μ or less, and more preferably 0°05 μ or less.

The smaller the distance between the fine particles, the better. In the present invention, it is necessary that the thickness be 30μ or less, and more preferably 5μ or less.

The larger the amount of the Ci fine particles, the better. Up to 20% by volume, dispersion strengthening can be expected, but if the volume ratio exceeds 20%, no further effect can be expected, and it is difficult to disperse into 1jJ of molten aluminum, so the upper limit is set. 20>.

Misfire I! To produce a dispersion-strengthened eutectic A1 alloy of
It is necessary to uniformly disperse the reinforcing fine particles into the eutectic A1 alloy molten metal by appropriate means such as stirring, then pressurize and rapidly cool the molten metal. Here, the cooling rate is 25 to b.Next, embodiments of the present invention will be described with reference to the drawings.

Example In this example, an aluminum alloy (JIS AC8A, Cu: 0.0% by weight) was used as the matrix alloy.
9%, 3i: 11.5%, Mg: 1°2%, Fe:
0.2%, Nj: 1.3%, Al: balance) and using SiC with an average particle size of 0.05 μm as fine particles for dispersion strengthening to manufacture a connecting rod. At this time, as a casting method,
We used a vertical pressure casting method that allows rapid cooling of the molten metal and good pressure transmission to the molten metal.

First, the aluminum alloy raw material is put into the melting furnace.
After the molten metal was dissolved, SiC fine particles were mixed into the molten metal using an inert gas as a carrier while stirring the molten metal. The molten metal thus prepared was poured into a vertical pressure casting apparatus shown in the drawing to manufacture a connecting rod.

The figure is a cross-sectional view of the main part of a vertical pressure casting apparatus, where ``■'' is the second mold, and 2 is the lower mold. The upper die 1 and the lower die 2 define a rocker arm-shaped product cavity 3. Type 1.2
A plunger sleeve 4 is provided at the center of the plunger sleeve 4, and a pressure plunger 5 and a counter plunger 6 are slidably fitted into the plunger sleeve 4. Each plunger 5.6 has a pressure tip 7 at its tip.
and a counter chip 8 are attached. Further, the product cavity 3 and the plunger sleeve 4 are communicated via a gate 9. In addition, 10 is a pouring hole, and 11 is an extrusion pin.

Next, the operation will be explained.

The mold was clamped, the gate 9 was closed by the counter chip 8, and the pressure plunger 5 was pulled up to the state shown in the figure.

Next, molten aluminum alloy 12 mixed with SiC fine particles was poured from the pouring spout.

After that, gradually lower the counter chip 8 and gently lower the molten metal 1.
2 was introduced into the product cavity 3. When 1/4 to 1/3 of the molten metal was introduced into the product cavity, the pressure plunger 5 pressurized the molten metal 12 to rapidly fill the product cavity 3 with the molten metal 12.

After solidification, the mold was opened and the product was removed using an extrusion bottle.

This rocker arm was manufactured by changing the amount of SiC dispersed.

As a result, the size of the dendrite near the surface of the rocker arm was 2μ, and the size at the center was about 12μ. Also, 5
It was confirmed that iC0) ff6 particles were mixed in the dendrite.

In this example, a tensile test (
JIS No. d test piece) was conducted. The results are shown in Table 1.

From Table 1, it can be seen that the strength of the dispersion-strengthened eutectic^1 alloy of the present invention is significantly improved.

It was also confirmed that the dispersion-strengthened eutectic^1 alloy of the present invention also has improved toughness.

As described above, the dispersion-strengthened eutectic A1 alloy according to the present invention has significantly improved strength compared to the conventional eutectic A1 alloy, so it can be used in parts that require light weight and strength, such as wheels.
It can be applied to automobile parts such as knuckle arms.

[Brief explanation of the drawing]

The drawing is a sectional view of a main part of a vertical pressure casting apparatus used in an embodiment of the present invention. 1 --- Upper mold 2 --- Lower mold 3 --- Part cavity 4 --- Plunger sleeve 5 --- Pressure plunger 6 --- Counter plunger 7 --- Pressure tip 8 --- One counter tip L --- Kate 10 --- One pouring spout 11 -- Ejection pin 12 -- One -- One molten metal

Claims (1)

[Claims] (1) A dispersion-strengthened eutectic aluminum alloy in which reinforcing fine particles are dispersed in an aluminum matrix and dendrites are crystallized, the fine particles having a particle size of 0.
The distance between particles is 30μ or less, and the volume ratio is 20μ or less.
% or less, and the dendrite size is 2.
A dispersion-strengthened eutectic aluminum alloy having a particle diameter of 0μ or less, wherein the fine particles are dispersed even in the dendrites.