JPS6247449A - 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. Ni 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 5-30wt% Ni as the 1st added element, 1-10wt% Zr as the 2nd added element, 1-10wt% one or more among Fe, Mn, Cr, W, Co, Mo and Ti 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 The present invention relates to a heat-resistant aluminum powder metallurgy alloy. 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. It is.

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, 261B, 4032 etc.)
When the temperature exceeds 0'C, the strength is significantly reduced.

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

Even in the case of SAP, in which aluminum oxide is 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/sec or more, and the resulting powder or ribbon-shaped thin strip is formed by powder metallurgy. A method of forming an aluminum alloy has been proposed (U.S. Pat. Nos. 4,347,076M 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 As a result of various studies conducted in view of the current state of the technology as described above, the present invention has been developed by adding specific additive elements to an aluminum alloy containing nickel as the main additive element, and adding specific additive elements to the molten metal. The aluminum powder metallurgical alloy obtained by cooling under specific conditions not only has excellent strength at high temperatures, but also has the unique property of having extremely small decreases in strength and elongation after exposure to high temperatures. I found out. That is, the present invention provides the following alloy and method for producing the same.

■(i) 5 to 30% by weight of Ni as the first additive element, (1
1) 1 to 10% by weight of Zr as the second additive element, and (iii) Fe, Mn, Cr, W as the third additive element.
, Co, Mo and 7-i, and the remainder consists of Al and inevitable impurities.
The content of the additive element is larger than the content of each of the second and third additive elements, and the tensile strength is 40 kg/mn+
A heat-resistant aluminum powder metallurgical alloy characterized by an elongation of 2 or more and an elongation of 5% or more.

■(i>Ni5 to 30% by weight as the first additive element, (i
i) Zr1 to 10ffiffi% as the second added source,
and (iii> Fe, Mn, Cr as the third additional element,
Contains 1 to 7% by weight of at least one of W, Co, Mo, and Ti, with the remainder consisting of Al and unavoidable impurities;
The content of the additive element is substantially 105
Forming particulates, flakes, thin wires, or ribbons at a cooling rate of less than °C/SeC, and molding them as they are or further broken into pieces if necessary. A method for producing a heat-resistant aluminum powder metallurgy alloy.

In the present invention, 5 to 30% by weight of Ni as the first additive element and Zr1 as the second additive element are added to the aluminum.
~10 wt% and FeSMnXC as third additive element
, rlw, at least one of Co, Mo and Ti 1-1
It is essential that the content of the first additive element be 0% by weight and that the content of the first additive element be greater than the content of each of the second and third additive elements. If any of these conditions are not met, the desired effects cannot be obtained, as is clear from the redistribution examples and comparative examples.

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 105°C/second is cold preformed according to a conventional method, and then hot worked. By doing so, the density of the product is almost 100%. 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. Also, the melt spinning method, which belongs to the ultra-rapid solidification method,
105°C by adopting conditions that increase the thickness or diameter of ribbon-like thin strips, thin wire-like objects, or flake-like objects formed by the melt extraction method, etc.
It is possible to obtain materials with desired properties with cooling rates of less than 1/2 seconds. 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 10''°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, a material with a particle size of about 40 mesh or less may be formed at a pressure of 700 kg/cm2.G or more, and then hot worked at a temperature of about 200'C. The cold preforming may be carried out by any method that allows a molded body to be obtained that can be handled when proceeding to the subsequent hot working step, and may be carried out, 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 and comparative examples will be shown below to further clarify the features of the present invention.

Example 1 A molten metal containing the additive elements shown in Table 1 was atomized by the atomization method to form 1 q of powder of about 100 mesh or less at a cooling rate of about 10'°C/sec.

Note: Samples Nos. 3, 6, 9, 11 and 13 have compositions outside the scope of the present invention;
, 5, but was obtained by the pinning method at a cooling rate of 105~b.

The powder obtained above was cold preformed at a pressure of 2830 kmCm2 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'.
Extrusions were obtained at ~1,2×10' kg/cm2.

Second. The table shows the extruded material and the extruded material at 350'C.
It shows the tensile strength and elongation at room temperature when annealed for 0 hours and 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. 5 and 12, even if the composition is 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 will decrease. 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 30% by weight of Ni as the first additional element;
(ii) 1 to 10% by weight of Zr as the second additive element, and (iii) Fe, Mn, Cr, W, as the third additive element.
Contains 1 to 10% by weight of at least one of Co, Mo, and Ti, with the remainder consisting of Al and unavoidable impurities;
A heat-resistant aluminum characterized in that the content of the additive element is greater than the content of each of the second and third additive elements, the tensile strength is 40 kg/mm^2 or more, and the elongation is 5% or more. Powder metallurgy alloy. [2] (i) 5 to 30% by weight of Ni as the first additional element,
(ii) 1 to 10% by weight of Zr as the second additive element, and (iii) Fe, Mn, Cr, W, as the third additive element.
Contains 1 to 10% by weight of at least one of Co, Mo, and Ti, with the remainder consisting of Al and unavoidable impurities;
The content of the additive element is substantially 10^ from the Al alloy molten metal which is higher than the content of each of the second and third additive elements.
Forming a particulate material, a flake-like material, a thin wire-like material, or a ribbon-like thin strip material at a cooling rate of less than 5 ° C./sec, and molding the material as it is or further cut into pieces as necessary. A method for producing a heat-resistant aluminum powder metallurgy alloy.