JPS6247447A - Heat resistant aluminum alloy for powder metallurgy and 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% Mo as the 2nd added element, 1-7wt% one or more among Mn, 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 loss in strength and elongation even after long-term use at high temperatures, so they are useful as aircraft parts, automobile engine parts, electrical equipment parts, hydraulic and pneumatic equipment parts, and even as high-temperature structural materials. I'll go.

Prior art and its problems Aluminum and its alloys generally have low strength at high temperatures, and especially high strength at room temperature. Aluminum alloy (AA201
8.2218.2618.4032 etc.), 2
If the temperature exceeds 00°C, the strength will drop significantly.

As for thermal stability, it is inevitable that the strength at room temperature will decrease significantly after long-term exposure to temperatures of 150'C or higher, for example.

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 10"°C/sec or more, and the resulting powder or ribbon-shaped thin strip is formed by powder metallurgy. A method of making an aluminum alloy has been proposed (U.S. Pat. Nos. 4,347,076 and 4,464,19
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 researches in view of the current state of the technology as described above.

The aluminum powder metallurgy 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 excellent strength and elongation after exposure to high temperatures. It has been found that this material has the unique property of having an extremely small decrease in That is, the present invention provides the following alloy and method for producing the same.

[1] (i) 5 to 17% Fe as the first additional element,
(ii) 1 to 7% by weight of Mo as the second additive element, and (iii) 1 to 7% by weight of at least one of Mn, Cr, W, Co, and Ni as the third additive element, with the remainder being A.
1 and unavoidable impurities, the content of the first additive element is greater than the respective contents of the second and third additive elements, the tensile strength is 40 kg/mm2 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 Mo as the second additive element, and (iii > Mrl, Cr, W, C as the third additive element)
Contains 1 to 7% by weight of at least one of O and 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 the molten Al alloy, it is practically 10”°C/5e
It is characterized by forming particulates, flakes, thin wires, or ribbon-like thin strips at a cooling rate of less than 1C, and molding them as they are or further cut into pieces as necessary. A method for producing heat-resistant aluminum powder metallurgy alloys.

In the present invention, Fe5 to 17% by weight as the first additive element and MO1 as the second additive element are added to the aluminum.
~7% by weight and Mn, Cr, W as the third additional element,
It is essential to contain 1 to 7% by weight of at least one of Co and N1 (7) and to make the content interval of the first additive element larger than the content interval 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 05°C/sec is cold preformed according to a conventional method, and then hot Through processing, a product with almost 100% density can be obtained. The lower limit of the cooling rate is preferably 102°C/sec. The method for cooling the molten metal is not particularly limited, but an atomization method is exemplified as a typical method. In addition, by adopting conditions that increase the thickness or diameter of ribbon-like thin strips, thin wire-like objects, or flake-like objects formed by melt spinning methods, melt extraction methods, etc. that belong to ultra-rapid solidification methods, , 105°
It is possible to obtain materials with desired properties with cooling rates of less than C/sec. 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 obtain a predetermined result 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 produce a flake-like material having the desired characteristics as a cooling rate of The cooling rate may be 105° C./second or more in some cases.

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 during forming processing.

Although the conditions are not particularly limited, it is sufficient to form a material with a particle size of about 40 mesh or less at a particle size of 700 km cm2.0 or more, and then hot work it at a temperature of about 200°C. The cold preforming may be performed by any method that allows a molded product to be handled when proceeding to the subsequent hot working step, and may be performed, for example, by mechanical pressing, isostatic pressing, or the like. Examples of hot working methods include hot extrusion, hot 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 almost loses its excellent properties even after being exposed to high temperatures for a long time. It can be maintained without any problems.

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 10'C/sec.

Note: Samples No. 3.6.10 and 12 have compositions outside the scope of the present invention.

No. 11 has the same composition as No. 5, but the cooling rate is 105
~b This is obtained from the bed.

The powder obtained above was cold preformed at a pressure of 2830 kg/cm'' to form a molded body with a diameter of 3 cm x height of 7.6 cm, and then extruded at 400'C and a pressure of 0.6 x 10' at an extrusion ratio of 9.
~1.2X10' kmMcm2F extruded material was obtained.

Table 2 shows the extruded material and the extruded material at 350'C.
The tensile strength and elongation at room temperature when annealed at 400'C for 64 hours are shown. For sample No. 12, 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 and are difficult to hot extrude, which limits their field of use.

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 Nos. 5 and 11, even if the composition is within the composition range of the present invention, if the cooling rate during powder production exceeds iQ5°C/sec, the extruded material Elongation is small.

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

(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 Mo as the second additive element, and (iii) 1 to 7% by weight of at least one of Mn, Cr, W, Co, and Ni as the 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 Mo as the second additive element, and (iii) 1 to 7% by weight of at least one of Mn, Cr, W, Co, and Ni as the 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.