DE2658504C2 - Method of making an alloy - Google Patents

Description

3 4

len vacuum treatment is said to have melted the content of certain of 600 torr. Then it is in a permanent mold Impurities, in particular undesirable from pure recrystallized alumina with an upper sodium, are reduced. shot of 1.1% by weight for evaporation losses

It is the object of the invention. Alloys or interweigh solid samarium with the molten one

metallic compounds of the type mentioned at the beginning 5 cast over cobalt. So that the samarium can be

with great accuracy with regard to the desired, mutually encircling cobalt shell, was

chiometric composition and high purity the previously the bottom and the side surfaces of the K jkille

of the structure and covered with solid cobalt pieces as homogeneously as possible in a crucible,

to manufacture. Furthermore, the evaporation losses during the pouring over with the molten liquid

of the easily evaporating component as low as possible, cobalt is initially formed which melts at around 600 ° C.

rigged. end eutectic. One after the other, that sa-

According to the invention, the ammonium-rich SmjCo and the cobalt-rich SmCo4- Component A, a superordinate element of the periodic system, the resulting inhomogeneous after cooling

stems, initially melted under protective gas, which are melted in the melting block with low power,

solid state component B. an element 15 This dissolves the low-melting eutectic below

from the group of rare earths and yttrium, then increasing melting point cobalt up to the

with the liquid component A poured over it, the 1335 ° C melting point of SmCo _{5 is} reached.

After cooling, the melted block is held up again. As a result of the increase in the melting point, the melt becomes

melted, and then poured off the melt. enriched with samarium so that by changing the

By pouring over a high vapor pressure, 20 activity coefficients during this process For example, at the melting temperature, the compo- vapor pressure of the samarium is significantly reduced, nent A, and / or a strong affinity for reactive components B containing the entire melt containing cobalt ver gases with the component prevents both stronger evaporation of the Samate A, a high-melting protective jacket and a reaction of the Samarium with the Formed around component B This largely prevents the crucible material and possible oxidic constituents from evaporation losses of component B if the argon atmosphere divides. The high melting temperature easily evaporates and protects the component temperature of the cobalt, which is around 1500 "C, needs to be not to achieve homogenization of the alloy before undesired reactions with the crucible material or with reactive components of the protective gases. After the entire insert becomes liquid rend of the subsequent melting. 30 poured off the melt.

If, during overmolding, parts of the outer surface of the in an analysis of the alloy produced in this way were found

component B is not in a solid state or has a high structural unity, i.e. freedom from enclosed

Foreign constituents only poorly reached by the liquid component A, and a high degree of homogeneity

can be, it has proven to be particularly advantageous in terms of structure and composition. The cobalt

proved, these parts with solid material the composition was 65.0 wt .-% and therefore agrees with the

nent A to surround. desired target composition.

Exist in the phase diagram of an alloy system. For example, multi-component stems of components A and B, low-melting alloys with several high-melting components, can be melted homogeneously when pouring on top. B. Easily evaporating component B in which the next most suitable master alloys of the high-melting component A can be produced according to the components, which are then composed of the low-melting eutectics via which a high vapor pressure and / or a strong one are dissolved. This partial alloy formation is then cast with an affinity for components having reactive gases with a change in the chemical activity coefficient. If alloys are to be produced with several components of the easily evaporating component B within easily evaporating components, so that the vapor pressure is combined with the alloy, then this is lowered together with component B in the solid state. Since the melting block was poured over the high-melting component, the temperature of this consisting of a phase mixture, regardless of the number of alloy component melt block, can generally be considerably lower than that of component A, and then the 50 mold can be used for the next Homogenization of the alloy Melt block for homogenization of the alloy when it is also melted several times before the melt is melted at a correspondingly reduced temperature. The method according to the invention prevents

The case according to the invention has proven to be particularly advantageous in that the high-melting component

proper method for the production of homogeneous alloy 55 nent A after pouring practically the crucible

made of cobalt and samarium, since this reactive component B represents undesirable

Components form low-melting eutectics. functions of component B with the crucible material or

In particular noble gases are suitable as protective gas, both of the crucible linings and with reactive gases that consist of for example argon, and other gases, such as. B. Water - the melt atmosphere can be absorbed. If it does not go beyond 60 with the alloy components, an evaporation loss is easy react. evaporating component through the enclosing

In the following, the invention is intended to be based on a preferred jacket of the solidifying refractory component

Referred embodiment explained in more detail component largely prevented will:

For the production of a cobalt-samarium alloy 65 the nominal composition 65% by weight cobalt and 35% by weight of samarium is first made of pure cobalt in a vacuum induction furnace under an argon pressure

Claims (1)

1 2 Rods from the higher-melting component to patent claims: will be given (DE-PS 12 73 200). By this measure a relatively homogeneous melt block is obtained, I. Process for producing an alloy or since the drops formed during melting of the intermetallic compound of at least one lower melting component not prematurely high-melting component A and at least drain, but between the higher-melting another lower-melting component rods get stuck. There they only fall after some distance B, the at the melting point of component A ser alloying with the higher melting point a high vapor pressure and / or a strong AfFi component. nhät against reactive gases such as Sauer- 10 It is also already known. Alloys of the contains substance and nitrogen in one crucible, to produce the composition of CeCos and PrCös by characterized in that that first the components with a high affinity for oxygen Cr or praseodymium can be melted in a vacuum. - The component A, a transition element of the increasing the temperature of the melt becomes Periodic table, first under protective gas then slowly melted the alloy component cobalt, added, whereby now an argon atmosphere with a - The component in the solid state is a pressure of approximately 400 Torr above the melt te B, an element from the group of the rare is prescribed as compensation for the expected-earths and yttrium, then with the liquid the evaporation losses of the easily evaporating Component A poured over. 20 rare earth components, this is in an upper The melt block obtained in this way is weighed in by about 2% by weight after the cooling. After casting treatment is melted again, the melt is cooled down quickly and the casting - and the melt is then poured off. block then at about HOO ⁰ C under reduced Homogenized pressure (see e.g. IEEETransac- Z The method according to claim 1, characterized in that it is marked on Magnetics, Sept 1971, See 423 to 426). The disadvantage of this process is that the oxygen-affine ßenfläche of the grain in the solid state is rare earths in the molten state parts of the component B, which do not or only reduce crucible material when pouring the top and, for example, when the liquid component is poor A reaches AljOrTiegel unwanted Al-impurities become, take with solid material of the component A 30,
be surrounded. Finally, there is one method of making 3. The method according to claim 1 or 2, thereby known alloys of the type mentioned indicates that at a temperature under a protective gas atmosphere, the melt block first reaches the transition temperature Is melted, the melted below the elements, the melt up to the start-Schraelz temperature the high-shrinkage compo- 35 the solidification is cooled and the rare harvest A then lies in the cooled by direct diffusion 4. The method according to any one of claims 1 to 3, melt are introduced (DE-AS 21 61 461).
characterized in that the melt block obtained in the above-mentioned process, however, has been found to be disadvantageous in the case of an inert gas, in that the desired Legiedmck of about 600 Torr is melted. 40 composition, homogeneity and structural 5. Applying the method after one of the uniformity is difficult to achieve. Also lets Proverbs 1 to 4 on cobalt as component A and it does not exclude with any certainty that it is with Samarium as component B. high affinity for one of the alloy components reactive gases, for example from the protective gas 45 atmosphere can be absorbed, undesirable structural contamination can occur. In addition, high material losses can occur through the The invention relates to a method for producing evaporation of the light evaporator.Jen component an alloy or intermetallic compound formed during the melting process, at least one high-melting component A 50 is also a levitation melting process for the production and at least one other lower melting point of alloys known, in which, in the case of quantitative KoiTinonente B. the differences between the components in the melting point of the compost Component A has a high vapor pressure and / or a strong component next to that which is present in larger quantities Affinity for reactive gases, such as acid-suspended melting. This melt is left substance and nitrogen, in a crucible. 55 then onto the other compo- So far, alloys or intermetallic components have been covered. Both components then join each other Connections, the components of which are highly negative, are then melted in a floating manner. dung enthalpies of their oxides or nitrides, d. H. a hozen (US-PS 31 02 002). In this process, each he have oxygen or nitrogen affinity, and yet the existing difficulties with regard to the their homogeneity and the given composition of the vapor pressure of the easily evaporating component special requirements are made, but not resolved in Va-. The method that vacuum arc or electron beam furnace with itself a very high energy requirement, even just for consuming consumable electrode melted. A production of very small amounts of alloy, Such a consumable electrode can be made, for example, from In DE-OS 22 34 748 is a vacuum treatment bundled metal rods with different diameters 65 described for light metal alloys be built up, the rods from the lower the liquid light metal component of the alloy The melting alloy component has a larger size than the solid one in a vacuum furnace Ren diameter and is sprayed on the outside of the thinner alloy additive. With this special