US2659134A - Composite alloy - Google Patents

Description

1953 T. E. LEONTIS ET AL 2,659,134

COMPOSITE ALLOY Filed Aug. 16, 1950 INVENTORSQ Thomas E. Leon/11S i y Rober/ S. Busk A TTORNE Y6 m v A W M Patented Nov. 17, 1953 UNITED STATS QFFICE COMPOSITE ALLOY ware Application August 16, 1950, Serial No. 179,777

2 Claims.

The invention relates to a magnesium-base alloy article. It more particularly concerns a zinc-containing magnesium-base composite alloy having a high tensile strength and the lightness characteristic of magnesium.

The term magnesium-base alloy used herein means a magnesium alloy containing at least 80 per cent of magnesium by weight.

The invention is predicated upon the discovery that by die-expressing at elevated temperature a zinc-containing magnesium-base alloy in particulated form in admixture with particulated aluminum a high strength composite alloy extrusion is obtained. The composite alloy extrusion of the invention has the same compactness and. integrity as the usual magnesium-base alloy extrusions made by extruding a solid mass, such as an ingot of a magnesium-base alloy, but the metallographic structure of the composite product is uniquely different. Metallographic examination reveals a new type of structure in a magnesium-base alloy article. The structure is essentially multimetallic. Each of the particulated metals of the mixture which is extruded is changed to the form of elongated particles with the long axis parallel to that of the extrusion. The elongated particles are all welded one to the other into a solid mass without voids forming a product which may be subjected to all the metal working operations in use with conventional magnesium-base alloys, such as rolling, forging, drawing, welding, electroplating, heat treating, etc. The invention then consists of the composite magnesium-base alloy product and method of making the same herein fully described and 3 particularly pointed out in the claims, the following description setting forth several modes of practicing the invention.

In carrying out the invention, various aluminum-and zirconium-free magnesium-base alloys containing zinc may be used, such as those containing from about 0.5 to 8 per cent of zinc. It is advantageous to include in the zinc-containing magnesium-base alloy a conventional amount of manganese, e. g. from about 0.1 to 2.5 per cent, a generally desirable amount being about 1 per cent. If desired, the alloy also may contain calcium in amount up to 1.0 per cent, or copper in amount up to 0.5 per cent. The zinc-containing magnesium-base alloy, used as one of the in gredients of the composite alloy of the invention, is reduced to particulate form in any suitable way, such as by grinding or atomizing. The atomized form yields superior results and may be produced by forming a melt of the alloy and atomizing it by impinging a jet of a cool gas, e. g. natural gas, against a thin falling stream of the molten alloy. The atomized alloy consists of a mixture of various sized fine spherical rapidly solidified particles, the particles having a very fine grain structure. It is desirable to screen out particles coarser than those passing about a 10 to 20 mesh standard sieve.

The aluminum ingredient of the mixture of particulate metals to be extruded according to the invention, is elementary aluminum which has been finely divided in any convenient manner. Its particle size is preferably made finer than that of the zinc-containing aluminumand zirconium-free magnesium-base alloy with which it is to be mixed.

Before extrusion, the particulated metals are mixed together in any convenient manner to form a uniform mixture of the metal particles comprising the extrusion charge. The relative amounts of the particulated zinc-containing magnesium-base alloy and particulated aluminum are adjusted so that there is at least 0.1 part by weight of the particulated aluminum per 100 parts of the mixture. Beneficial results are had with up to as much as about 6 parts of particulated aluminum per 100 parts of the mixture. A preferred proportion is about 3 parts of the particulated aluminum per 100 parts of the mixture.

The mixture of particulated metals is charged into the heated container of a ram extruder, having a suitable size container and die opening and subjected to extrusion pressure to cause the mixture of particulated metals to be heated and extruded through the die opening.

As to the extrusion conditions, the temperature of the particulated metal mixture in the con tainer may be about the same as that conventionally employed for extruding solid ingots of the known zinc-containing aluminum-freemagnesium-base alloys, e. g. 600 to 800 F. The ratio of the cross-sectional area of the extrusion container to that of the die opening has a material efiect on the mechanical properties of he composite extrusion product obtained. A desirable ratio is at least about 30 to 1, although ratios as high as 150 to 1 or more may be used. The speed of extrusion may be varied over a wide range and depends to some extent upon the size and shape of the die opening. In any case, the extrusion speed is to be held down to that at which the extrusion produced is free from hot shortness. A safe extrusion speed may be ascertained by visual examination of the product as it extrudes, the hot shortness being evident as 3 cracks in the extruded product and sharply reduced strength. The composite extrusion prod uct may be subjected to any of the fabrication operations conventionally in use with the con- By putting a charge of the mixture of the metals involved under pressure while at heat, as with the apparatus shown, the mixture of metal particles is compacted but not subjected to furventional or non-composite magnesium-base al- 5 ther mixing before extrusion. The metals origiloys, such as rolling, forging, drawing and weldnally in the charge as individual metal particles ing, and its tensile properties may be enhanced do not lose their original distinctive composition by heat treatment. except at the surfaces of the union of the differ- The invention may be further illustrated and out metal particles which become extended and explained in connection with the accompanying l lengthened during extrusion. At these surfaces, drawing in which: during extrusion or heat treatment, some diffu- Fig. 1 shows a schematic sectional elevation sion of metal takes place between the zinc-conof an extrusion apparatus suitable for use in taining particles and the aluminum particles, practicing the invention; forming composite alloy.

Fig. 2 is a similar view to Fig. 1 showing a 15 The following examples, set forth in the table modification of the apparatus; and below, are illustrative of the invention:

Table Com osition of extrusion charge of particulated Mg Mechanical propertiesin 1,000 5.1.

alloy mixed with particulated aluminumv Exmislon 9mm of extrusions 1 Example O. Blank Weight Weight Redw Extrusion ASK Aged 11.1. H.T.A.

Analysis of Mg alloy 5:5, T???" tion in diameter,

alloy Al area TYS TS TYs TS TYS 'IS 'lYS is 99.9 1.13% Z11, balance Mg 0.1 34:1 44 30 43 24 3 26 37 99. .do 05 34:1 41 34 42 37 20 33 3 94.0 do 0.0 34:1 40 30 40 32 41 42 Blank 1...- 100 .do None 34:1 33 39 24 30 22 41 4 99.0 0.95%2 1.0 3411 37 31 33 27 3s 29 37 100 1o None 34:1 37 2s 36 19 32 23 33 99.9 1.2%M 3.9% Zn, balance Mg" 0.1 34:1 42 49 24 35 34 41 99.5 do 0.5 3411 40 45 27 40 34 43 99.0 .do.. 1.0 34:1 45 42 49 32 45 40 49 91.0 ...do 3.0 3411 39 45 50' 35 44 41 49 9 94.0 do 0.0 341 47 42 44 41 52 43 52 B1nnk3 100 .do None 341 41 42 49 29 39 3s 44 10 99.0 1.03% Zn,0.62% Ca, balance Mg 1.0 64:1 40 34 41 22 3e 25 37 Blank 4.... o None 04=1 40 31 40 20 33 21 3s 1 0.77% Zn, 0.147 Cu balanceM 1.0 150:1 37 30 33 27 3s 23 3s 13 1mm; 5-.-. 10 do N e 1501 6 3; 2% i4 23 3s .3 150:1 2 4 Blank 6..-. None 1501 "{24 41 42 49 22 32 TYS=tensile yield strength defined as the load at which the stress TS tensile strength.

Fig. 3 is a similar view to Fig. 1 showing another modification of the apparatus.

As shown, the apparatus comprises, in its three forms, an extrusion container I adapted to confine a charge 2 of the mixture of metal particles to be compacted and extruded. The container is provided with a heating element 3, In Fig. 1, one end of the container l is closed'by the die plate 4 in which is provided the die opening 5. In this form of the apparatus, the charge 2 is caused to be compacted in the container and extruded through the die opening 5 by application of pressure by means of the dummy block 6 forced into the bore 1 of the container by the ram 8 to form the extrusion 9.

In the form of the apparatus shown in Fig. 2, the container I is closed at one end by the plate I0. The other end of the container received the die block I I carried by the hollow ram I2 which forces the die block into the container causing the charge 2 to be compacted and to extrude through die opening I3 to form the extrusion I4 which extends into bore I5 of the hollow ram In the modification of Fig. 3, the container is closed at one end with a plate I6. The charge 2 is extruded as a tubular extrusion I7 through the annulus I8 around the die block I9 while it is forced into the container by the ram 20.

The forms of the apparatus shown are conventional.

F. followed by heat treating for 16 hours at 350 F.

curve deviates 0.2% from the modulus line.

In making the composite alloys shown in the foregoin table, the zinc-containing magnesiumbase alloys used were in atomized form the particles of which were of various sizes substantially all passing through a 20 mesh sieve while being retained on a 200 mesh sieve. The particles of the particulated aluminum were of generally finer size than those of the magnesium alloy. The two particulated metals were mixed together in the proportions indicated and the mixture charged into the heated container of a ram ex truder of the type illustrated in Fig. 1. For the blanks, the zinc-containing magnesium alloy in the same particulated form as used in the mixtures was extruded alone under comparable extrusion conditions. The rate of extrusion of the examples numbered 1 to 10, inclusive, and Blanks 1, 2, 3 and 4 was about 2 lineal feet of extrusion per minute. In Example 11 and Blank 5, the rate of extrusion was 5 lineal feet per minute. In Example 12 and Blank 6, the rate of extrusion was 15 lineal feet per minute.

Among the advantages of the invention are that a workable metal product is obtained having the light weight characteristic of magnesiumbase alloys but with enhanced strength, which is generally retained or increased by a more or less prolonged (e. g. 1 to 20- hours) heating in the temperature range of about 300 to 800 F. This property enables the composite alloy to be hot worked in the foregoing temperature range without loss of strength.

We claim:

1. The method of making a solid composite high strength metal product which consists in forming a m'xture of two particulated metals, one consistin of aluminum in amount from 0.1 to 6 per cent of the weight of the mixture, the other forming the balance of the mixture and consisting of a magnesium-base alloy containing 05 to 8 per cent of zinc, up to 2.5 per cent of manganese, up to 1 per cent of calcium, and up to 0.5 per cent of copper, the balance of the alloy being magnesium, and die expressing the mixture at a temperature between 600 and 800 F'.

2. A composite metal body consisting of two particulated metals one consisting of aluminum in amount from 0.1 to 6 per cent of the weight of the body, the other forming the balance of the body and consisting of a magnesium-base alloy containing 0.5 to 8 per cent of zinc, up to 2.5 per cent of manganese, up to 1 per cent of calcium, up to 0.5 per cent of copper, the balance of the alloy being magnesium, the particles being elongated, orientated in the same direction, and welded together into an integral solid.

THOMAS E. LEONTIS. ROBERT S. BUSK.

6 References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Treatise on Powder Metallurgy by Goetzel, vol. 2, pp. 500, 740, 741. Published in 1950.

Symposium on Powder Metallurgy, Buffalo Spring Meeting, March 3, 1943, published by American Society for Testing Materials, Philadel- 25 phia, Pa., pages 42 and 43.

Claims (1)

1. 2. A COMPOSITE METAL BODY CONSISTING OF TWO PARTICULATED METALS ONE CONSISTING OF ALUMINUM IN AMOUNT FROM 0.1 TO 6 PER CENT OF THE WEIGHT OF THE BODY, THE OTHER FORMING THE BALANCE OF THE BODY AND CONSISTING OF A MAGNESIUM-BASE ALLOY CONTAINING 0.5 TO 8 PER CENT OF ZINC, UP TO 2.5 PER CENT OF MANGANESE, UP TO 1 PER CENT OF CALCIUM, UP TO 0.5 PER CENT OF COPPER, THE BALANCE OF THE ALLOY BEING MAGNESIUM, THE PARTICLES BEING ELONGATED, ORIENTED IN THE SAME DIRECTION, AND WELDED TOGETHER INTO AN INTEGRAL SOLID.

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