JPH02149631A - Low thermal expansion aluminum alloy having excellent wear resistance and heat conductivity - Google Patents

Abstract

PURPOSE:To obtain the title Al alloy by adding specific amounts of Ni, Si, Cu, Mg and other metallic elements to Al. CONSTITUTION:An Al alloy having the compsn. of which, by weight, 8 to 10% Ni, 4 to 10% Si, 2 to 5% Cu and 0.3 to 2% Mg or furthermore one or more kinds among 0.01 to 1% Cr, 0.01 to 1% Mn, 0.01 to 0.5% Zr, 0.01 to 0.1% V, 0.01 to 1% Ti, 0.01 to 5% Zn and 0.01 to 5% Fe are added and incorporated is poured into a mold heated to its liquidus temp. +100 deg.C and is solidified under pressure into a billet. The billet is extruded into a round bar or the like, is subjected to solution heat treatment, is thereafter water-cooled and is successively subjected to aging treatment, by which the Al alloy material having excellent wear resistance and heat conductivity and having small thermal expansion coefficient can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is applicable to wear-resistant pistons used in, for example, automobile parts and various mechanical parts that have a small geothermal expansion coefficient and are required to have wear resistance and thermal conductivity. This invention relates to a low thermal expansion aluminum alloy with excellent properties and thermal conductivity.

Conventional technology Conventionally, as this type of aluminum alloy, Al-SL has been added with St as an element to improve wear resistance.
aluminum alloys are well known,
Commonly used.

Problems to be Solved by the Invention However, when increasing the amount of Si added to improve wear resistance, the wear resistance improves and the coefficient of thermal expansion decreases, but the castability, machinability, and forgeability deteriorate. There is a problem that the amount of addition is naturally limited.

In view of these circumstances, this invention was made with the purpose of providing an aluminum alloy that has excellent mechanical properties such as wear resistance, and excellent physical properties such as thermal conductivity and thermal expansion. be.

As a means to solve the problem, this invention has been developed as a result of intensive research.In addition to hard particles of St, Al3Ni intermetallic compound is dispersed, and at the same time, Cu and Mg are coexisting, thereby improving wear resistance. This work was completed based on the findings of the authors, who found it possible to sufficiently improve the properties of steel and thermal expansibility, while at the same time improving the thermal conductivity, castability, machinability, and forgeability. .

That is, the first aspect of the present invention has wear resistance and heat resistance, which contains Ni: 8 to 10%, Si: 4 to 10%, Cu: 2 to 5%, Mg: 0.3 to 296, and the balance is Al and inevitable impurities. A low thermal expansion aluminum alloy with excellent conductivity.

Furthermore, the second invention provides, in addition to the essential elements Si, Ni, Cu, and Mg of the first invention, Cr: 0.01 to 1% Mn: 0, 01 to 1% Zr: 0. 01~0. 596V: 0.0
Contains one or more of the following: 1 to 0.1% Ti: 0.01 to 1% Zn: 0.01 to 5% Fe: 0.01 to 5%, and the remainder consists of Al and inevitable impurities A low thermal expansion aluminum alloy with excellent wear resistance and thermal conductivity.

In addition, in this specification, "%" refers to "% by weight".
”.

The significance of the above-mentioned alloy additive elements and the reason for limiting their content are as follows.

That is, Ni forms the A,Q3Ni intermetallic compound and is dispersed in the alloy, which mainly contributes to improving wear resistance and lowering the coefficient of thermal expansion.If the content is less than 8%, the above effects are not achieved. If the content exceeds 10%, thermal conductivity will be inhibited. A particularly preferable content is 8.
It is about 5 to 9.5%.

St improves wear resistance and strength as well as lowers the coefficient of thermal expansion. If it is less than 4%, sufficient effects may not be obtained depending on the application, and if it exceeds 10%, primary St
This may cause surface cracks during extrusion.

A particularly preferable content is about 7 to 9%.

, Cu, and Mg are all used to increase strength, and if Cu is less than 2% and Mg is less than 0.3%, this effect will be small; on the other hand, if Cu is more than 5% or Mg
When g exceeds 2%, coarse crystallized substances are formed, and the mechanical properties are rather deteriorated. Particularly preferable content is
2.5-4.5% in CU, 0°5-4.5% in Mg
It is about 1.5%.

C, Mn, Zr, V, Ti, Zn, and Fe are all effective in improving the mechanical properties of the alloy, and in this invention, they are evaluated as equivalent to each other in terms of the effect of addition. When the individual content of any of them is less than 0.01%, it is insufficient to realize the above effect, and conversely, when the content exceeds the specified value and is excessively contained (Cr, Mn5
Ti over 11%, Zr: over 0.5%, ■: over 0.1%, Z
n, Fe: more than 5%), the above effects are saturated and no other particularly beneficial effects are produced.

By the way, although the alloy of the present invention can also be manufactured by a conventional continuous or semi-continuous casting method, it is preferably manufactured by a pressure solidification method. This pressure coagulation method will be explained as follows. That is, by melting the alloy of the present invention and pouring the molten metal into a pressure solidification mold and solidifying it under pressure, a billet with uniform and fine crystal grains without defects is created. The pressurized solidification mold may utilize a container of an extruder. That is, the molten aluminum alloy may be directly poured into the container and solidified while being pressurized by the stem. Of course, in this case, it is necessary to close the front surface of the container with a blind die to prevent the molten metal from blowing out during pressurized solidification. Further, when pouring the molten metal, it is desirable that the mold be preheated to about 300 to 350°C.

This makes it possible to obtain a finer texture in the billet. That is, if the temperature is less than about 300° C., solidification of the aluminum will start immediately after pouring, making it difficult to fully achieve the effect of pressure solidification. On the other hand, if it is heated to a high temperature exceeding 350° C., the cooling rate slows down, and crystallized substances tend to grow, making it difficult to sufficiently achieve the above-mentioned refinement effect. Immediately after pouring the molten metal, the molten metal in the mold is pressurized by a pressurizing piston to advance solidification, thereby creating a billet. That is, a billet is created by a pressure coagulation method. The pressing force at this time is 50Kyflad
or more, preferably 500 to 1000/(g
It is preferable to set it to about f/d. The magnitude of this pressing force does not significantly affect the quality of the billet. However, if the pressure is less than 50Kfff/cm, the effect of preventing casting cracks and refining grains by the pressure solidification method is insufficient.On the other hand, even if a high pressure of more than 9f/al is applied to 1500, the energy required for it is insufficient. It is rather useless as it is not possible to see a proportional improvement in the effect commensurate with the increase. In this manner, by solidifying the aluminum alloy under a predetermined pressurized state, a small billet of crystallized material can be created without causing casting cracks. The billet produced by the above pressure solidification method is then extruded to form the desired aluminum alloy material. Here, the billet may be used in a solid state that has been cooled once, but preferably, the temperature of the billet is adjusted to a temperature suitable for extrusion processing, for example, about 1/2 of the liquidus temperature, by the progress of the pressure solidification. It is recommended that the pressurized solidification process be completed when the temperature has decreased to a certain degree and the mixture has reached a semi-molten state, and that the extruder be immediately loaded into the container of the extruder and extrusion be started. By adopting such a procedure, it is possible to omit the billet heating step during extrusion processing, saving the energy and time required for heating, improving the manufacturing efficiency of alloy extrusions, and reducing manufacturing costs. can enjoy benefits.

Effects of the Invention As is clear from the following Examples, the aluminum alloy according to the present invention has a lower Si content than a comparative alloy in which one or more of the alloy compositions deviates from the range of the limitations of the alloy composition. Despite the limitations, it is possible to achieve excellent effects in terms of wear resistance, thermal conductivity, and low thermal expansion.

Examples For each of the present invention alloy and comparative alloy shown in Table 1, the molten metal is poured into a pressure solidification mold heated to the liquidus temperature +100°C, and solidified under a pressure of 1000 Kyf/Ci to form a billet. and extrude this billet at a temperature of 49
Extruded into a round bar with a diameter of 12III at 0°C,
A sample material was obtained by solution treatment at 0°C for 6 hours, water cooling, and aging treatment at 180°C for 7 hours.

The abrasion resistance, thermal conductivity, and coefficient of thermal expansion of each sample material were then examined. The results are shown in Table 2.

The abrasion resistance test was conducted using an Okoshi type abrasion tester using a rotating disk, and the applied load was 2. IKy, friction distance: 60
0m, Friction speed: 3.67m/S1 mating material: FC-
30 (J Is), test surface: Emery Paper 1200
The specific wear amount of the sample material when rubbed under the test conditions of 1111 was evaluated.

[Margin below]

As shown in the results in Table 2 above, the alloy of the present invention was confirmed to have much improved wear resistance and superior thermal conductivity and low thermal expansion compared to the comparative alloy. Obtained.

that's all

Claims (2)

[Claims] (1) Contains Ni: 8-10% Si: 4-10% Cu: 2-5% Mg: 0.3-2%, with the balance being Al and unavoidable impurities. Excellent wear resistance and thermal conductivity. Low thermal expansion aluminum alloy. (2) Contains Ni: 8-10% Si: 4-10% Cu: 2-5% Mg: 0.3-2%, and Cr: 0.01-1% Mn: 0.01-1 % Zr: 0.01-0.5% V: 0.01-0.1% Ti: 0.01-1% Zn: 0.01-5% Fe: 0.01-5% One type Or a low thermal expansion aluminum alloy containing two or more of them, the balance being Al and inevitable impurities, and having excellent wear resistance and thermal conductivity.