JPS6247448A - Heat resistant aluminum alloy for powder metallurgy adn its manufacture - Google Patents

Abstract

PURPOSE:To provide characteristics such as superior strength and elongation at high temp. as well as ordinary temp. to an Al alloy for powder metallurgy by adding specified elements to an Al alloy contg. Fe as the principal added element, melting the resulting alloy and cooling the molten alloy under specified conditions. CONSTITUTION:The composition of a molten Al alloy is composed of 5-17wt% Fe as the 1st added element, 1-7wt% Ti as the 2nd added element, 1-7wt% one or more among Mo, Cr, W, Co and Ni as the 3rd added element and the balance Al with inevitable impurities. In the composition, the amount of the 1st added element is made larger than the amount of the 2nd added element and the amount of the 3rd added element. The molten Al alloy is cooled at <=10<5> deg.C/sec cooling rate to form granules, flakes, a fine wire or a ribbonlike thin strip. This product is worked as is or after it is broken into pieces as required.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to heat-resistant aluminum powder metallurgical alloys. The alloy products according to the present invention have little decline in strength and elongation even after long-term use at high temperatures, so they can be used as aircraft parts, automobile engine parts, electrical equipment parts, hydraulic and pneumatic equipment parts, and even as structural materials for high temperatures. is also useful.

Prior art and its problems Aluminum and its alloys generally have low strength at high temperatures, and particularly high strength at room temperature.The strength of so-called high-strength aluminum alloys at high temperatures is significantly reduced. In addition, aluminum alloy (AA2018
．． 221B, 2618.4032, etc.), 20
When the temperature exceeds 0'C, the strength is significantly reduced.

Regarding thermal stability, for example, after being exposed to temperatures of 150° C. or higher for a long period of time, it is inevitable that the strength at room temperature will decrease significantly.

In the case of SAP, which has aluminum oxide uniformly dispersed in aluminum, although it has excellent annealing softening resistance, it is difficult to say that it is satisfactory in terms of strength, toughness, etc., and is of little practical use. .

In recent years, various transition elements have been added to aluminum in amounts exceeding the solid solubility limit, the molten metal is solidified ultra-rapidly at a cooling rate of 105°C/second or more, and powder or ribbon-like thin strips are formed by powder metallurgy. A method of forming an aluminum alloy has been proposed (U.S. Pat. Nos. 4,347,076 and 4,46419).
No. 9). Although the aluminum powder metallurgical alloy thus obtained has excellent strength and thermal stability at high temperatures, its major drawbacks are low elongation and lack of ductility.

Means for Solving the Problems The present invention was developed as a result of various studies in view of the current state of the technology as described above.

An aluminum powder metallurgical alloy obtained by adding specific additive elements to Minilam alloy and cooling the molten metal under specific conditions not only has excellent strength at high temperatures, but also has a high After exposure, there was a decrease in strength and elongation.
It was discovered that it has the unique property of being small in size. That is, the present invention provides the following alloy and method for producing the same.

■(i) Fe5-17% as the first additive element, (1
1> 1 to 7% by weight of Ti as the second additive element, and (iii > MO, Cr, W, Co as the third additive element)
and 1 to 7% by weight of at least one of Ni, the remainder consists of Al and unavoidable impurities, and the content of the first additive element is greater than the content of each of the second and third additive elements. A heat-resistant aluminum powder metallurgy alloy having a tensile strength of 40 kM mm2 or more and an elongation of 5% or more.

[2] (i) 5 to 17% by weight of Fe as the first additional element,
(11) Til to 7% by weight as the second additive element, and (iii) MO, Cr, W, CO as the third additive element.
and 1 to 7% by weight of at least one of Ni, the remainder consists of Al and unavoidable impurities, and the content of the first additive element is greater than the content of each of the second and third additive elements. From a certain A9 alloy molten metal, substantially 10”°C/sec
A heat-resistant product characterized by forming particles, flakes, thin wires, or ribbons at a cooling rate of less than Method for producing aluminum powder metallurgy alloy.

In the present invention, 5 to 17% by weight of Fe as the first additive element and Ti as the second additive element are added to the aluminum.
1 to 7% by weight and Mo, Cr, W as the third additional element
, c○, and Ni in an amount of 1 to 7% by weight, and the content of the first additive element is required to be greater than the content of each of the second and third additive elements. . If any of these conditions are not satisfied, the desired effect cannot be obtained, as is clear from the Examples and Comparative Examples described later.

The aluminum powder metallurgy alloy of the present invention is produced, for example, as follows. A material obtained by solidifying a molten aluminum alloy containing the first, second, and third additive elements in a predetermined ratio at a cooling rate of less than 10"°C/sec is cold preformed according to a conventional method, and then hot By processing, the product has a density of almost 100%.The lower limit of the cooling rate is preferably 102°C/sec.The method of cooling the molten metal is not particularly limited, but the atomization method is a typical method. In addition, conditions for increasing the thickness or diameter of ribbon-like thin strips, thin wires, or flakes formed by melt spinning, melt extraction, etc., which belong to the ultra-rapid solidification method. By adopting 105℃
With a cooling rate of less than 1/sec, the material with the desired properties is
It is possible to In this case, if necessary, the product, such as a ribbon, is crushed prior to the subsequent shaping process.

Furthermore, in the twin roll method or the spray roll method in which a rapidly solidified material is obtained by colliding atomized particles with a rotating drum, it is possible to achieve a predetermined value by adjusting the materials of the rolls and drums, the distance between the rolls, the size of the atomized particles, etc. It is possible to obtain flakes having the desired properties as the cooling rate increases. Note that the materials obtained by these manufacturing methods also contain extremely fine particles, and the cooling rate of these extremely fine particles may be 105° C./second or more.

However, in the present invention, even if such particles are contained to some extent, the desired effect can be achieved.

Cold preforming and hot processing conditions during forming processing are as follows:
Although not particularly limited, it is sufficient to form a material with a particle size of about 40 mesh or less at a temperature of 700 k(]/cm2・G or more and then hot-process it at a temperature of about 200'C. Any method may be used as long as it can obtain a molded product that can be handled when moving to the hot working process, such as mechanical pressing, isostatic pressing, etc.Hot working methods include hot extrusion, hot hot working, etc. Examples include methods such as rolling, hot forging, hot pressing, and hot isostatic pressing.

Further, the molding process may be carried out by a conform method in which direct extrusion is performed without going through a cold preforming process, and in this case as well, it is possible to obtain a molded product with a density of approximately 100%.

Effects of the Invention The aluminum powder metallurgical alloy of the present invention has excellent properties such as strength and elongation not only at room temperature but also at high temperatures, and also retains most of its excellent properties even after being left separately at high temperatures for a long time. It can be maintained without damage.

EXAMPLES Hereinafter, Examples and Comparative Examples will be shown to further clarify the characteristics of the present invention.

Example 1 A molten metal containing the additive elements shown in Table 1 was atomized by an atomization method to obtain a powder of about 100 meshes or less at a cooling rate of about 104°C/sec.

Table 1 ■ ■ [Note: Sample Nos. 3.7.11 and 13 have compositions outside the scope of the present invention;

No. 12 has the same composition as No. 6 but has a cooling rate of 10"
It was obtained by melt spinning at ~107°C/sec.

The powder obtained above was cold preformed at a pressure of 2830 kmcm'' to form a compact with a diameter of 3 cm x height of 7.5 cm, and then extruded at an extrusion ratio of 9 at 400'C and a pressure of 0.6 x 10' ~
Obtain extruded material with 1.2X10' kmcm2.

Table 2 shows the extruded material and the extruded material at 350'C.
Figure 2 shows the tensile strength and elongation at room temperature when annealing at 400'C for 64 hours. For sample No. 13, an ingot with a diameter of 3 cm and a height of 7.6 cm was extruded.

Table 2 As is clear from the results shown in Table 2, alloys having compositions outside the range of the present invention have low elongation, are difficult to hot extrude, and have limited fields of application.

Furthermore, since the melting point of the alloy becomes very high, it becomes difficult to prepare powder by the atomization method.

Furthermore, as is clear from the comparison between Samples No. 096 and 12, even within the composition range of the present invention, if the cooling rate during powder production exceeds 105°C/sec, the elongation of the extruded material is small. .

In contrast, the aluminum powder metallurgical alloy of the present invention can be easily prepared as a raw powder by the atomization method, can be easily processed by hot extrusion, and has excellent properties even after long-term exposure to high temperatures. Maintains the same strength and elongation properties (
Pull.

(that's all)

Claims (1)

[Claims] [1] (i) 5 to 17% by weight of Fe as the first additional element;
(ii) 1 to 7% by weight of Ti as a second additive element, and (iii) 1 to 7% by weight of at least one of Mo, Cr, W, Co, and Ni as a third additive element, with the remainder being A.
1 and unavoidable impurities, the content of the first additive element is larger than the respective contents of the second and third additive elements, the tensile strength is 40 kg/mm^2 or more, and the elongation is 5
% or more. [2] (i) 5 to 17% by weight of Fe as the first additional element,
(ii) 1 to 7% by weight of Ti as a second additive element, and (iii) 1 to 7% by weight of at least one of Mo, Cr, W, Co, and Ni as a third additive element, with the remainder being A.
1 and unavoidable impurities, and the content of the first additive element is higher than the content of each of the second and third additive elements. A heat-resistant aluminum powder that forms particulates, flakes, thin wires, or ribbons at a cooling rate, and molds the same as it is or further breaks it into pieces as necessary. Method of manufacturing metallurgical alloys.