US2206537A - Magnetic metallic material containing tungsten - Google Patents

Description

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Patented July 2, 1940 UNITED smrss PATENT QFFifiE MAGNETIO METALLIC MATERIAL OGNTAIN- ING TUNGSTEN No Drawing.

3Claims.

This invention relates to metallic materials containing more than 83% of tungsten, and having densities exceeding or at least not substantially less than 15 gm./ml.

Materials, capable of being machined, containing more than 83% of tungsten together with nickel and copper are known and are valuable on account of their high density; they are usually prepared by sintering the powdered constituents together at a temperature below 1500 C. They are, however, only feebly magnetic. For certain purposes it would be an advantage if such materials had strongly magnetic properties. Ihe object of the invention is to produce materials of the kind described which, whilst having the essential characteristics of these known alloys, have also strongly magnetic properties.

I have found that the addition of a few per cent of iron to a material of the kind described confers upon it strongly magnetic properties. I.

' and the density does not approach 15. Again it is known that the addition of iron to a nonmagnetic metal will often produce a feebly magnetic alloy, whose magnetic properties can be regarded as due directly to those of the iron present. The materials produced according to the prwent invention are far more strongly magnetic than would be the case if the magnetism depended solely on the magnetism of the small proportion of iron present. Whilst the invention is in no way dependent on the theory, I believe the strongly magnetic properties are due to the formation of a phase containing nickel, tungsten and iron in solid solution. 1 1

According to the invention a metallic material contains more than 83% of tungsten, not less than 2% or nickel, preferably some copper, and some iron; has a density not substantially less than 15 gm./ml.; has a magnetic permeability greater than 2.

Twoembodimentsoftheinventionwillnow Application October 1, 1938, Serial In Great Britain October 4, 193'! be described by way of example. In the first a mixture of metal powders containing 88% tungsten, 5% nickel, 2% copper and 5% iron is pressed and sintered at a temperature of about 1450 C. so as to give a'coherent body. This rnaterial has a magnetic permeability greater than 10.

In the second mixture of metal powders containing 88% tungsten, 6% nickel, 4% copper and 2% iron is pressed and slntered in the same way. The permeability of'the resulting material is somewhat lower than the first example but still greater than 5.

If it is desired to obtain the highest possible density for a given permeability the proportion of copper should not be much more than half the proportion of nickel present. The presence of copper does not materially aflect the permeability or greatly increase the density obtainable, it no Y limit is placed on the temperature or duration of the sintering; but it enables a given density to be obtained at a lower temperature and/or with a shorter duration. It is preferable therefore that at least 1% of copper should be present.

It will thus be seen that I have provided a new composition of matter in the form of a magnetic material havinga density of at least 15 gm./ml. and consisting of a pressed and sintered mixture of tungsten, nickel, iron and copper powders having a composition by weight lying within the range 83 to 95% tungsten, 2 to 14% nickel, 2 to 14% iron and preferably 1 to 13% copper.

I claim:

1. A magnetic alloy having a density of at least 15 gm./ml. and consisthig of a pressed and sintered mixture oi tungsten, nickel, iron and copper powders having a compomtion by weight lying within the range 83 to 95% tungsten, i to 14% nickel, 2 to 14% iron and l to 13% copper.

2. An alloy according to claim 1 containing 88% tungsten, 5% nickel, 2% copper and 5% iron.

3. An alloy according to claim 1 containing 88% tungsten, 6% nickel, 4% copper and 2% d-nonen may s'rosa'r PRICE.