DE1061041B - Method for the production of composite cast parts from magnesium or a magnesium alloy and a base body consisting of metal or a metal alloy, in particular iron - Google Patents

Description

In many branches of technology, so-called composite casting processes are used, the aim of which is to to make the properties of two different materials usable at the same time in a workpiece. So are z. B. the combinations of iron and copper alloys, iron and aluminum or aluminum alloys, Iron and zinc and numerous other combinations are known. The combination Iron — aluminum is often used in such cases in which the good thermal conductivity or the low specific weight of aluminum are exploited can be.

Composite castings of the metal combinations described above are preferably produced by processes in which, by immersion treatment with the metal to be cast on, e.g. B. aluminum, a transition layer, ie a diffusion or bonding layer Me _x Alj ,, is formed in which both metals are involved, whereby a molecular bond between the two materials in question is achieved. The feature of all these composite casting processes is thus an intermediate layer, in the formation of which the two metals to be cast together are involved. It is also known to produce composite castings with an intermediate layer of a third metal, for example iron-magnesium composite castings with an intermediate layer of calcium. A composite casting process for iron and magnesium or magnesium alloys, which is desirable in the art, has not been able to be implemented since iron and magnesium neither diffuse into one another nor form compounds with one another and therefore an intermediate _{layer Me x} Mg ₁ could not be formed. It therefore seemed hopeless to come up with a casting method for casting magnesium and iron on the principle of the composite casting process described above.

The subject of the invention is a process which enables magnesium to be cast onto iron, a bond being achieved which has similar strength properties as are achieved in the other composite casting processes. When practicing this process, the procedure is that the workpiece is made of metal or metal alloys, ζ. B. iron-based (steel or cast iron) immersed in a known manner after appropriate surface cleaning in a melt of aluminum or aluminum alloys and thereby an intermediate layer of the general formula Me _x AIj can grow on the surface. After this has been done, the dipped iron part is inserted into the mold and the magnesium or magnesium alloy is cast onto the intermediate layer to produce a magnesium composite casting.

Method of manufacture

of composite castings made of magnesium

or a magnesium alloy

and one made of metal or one

Metal alloy, especially iron,

existing base body

Applicant:

Metallgesellschaft Aktiengesellschaft,
Frankfurt / M., Reuterweg 14

Dr. Gustav Gürtler, Frankfurt / M.,
has been named as the inventor

When casting onto a workpiece made of iron, the _{pure aluminum adhering to the Fe x} Alj ₁ layer or the corresponding aluminum alloy dissolves in the flowing magnesium, so that there is direct contact between the Fe _x Alj 1 layer and the magnesium. As in the case of the aluminum-iron composite casting process, one preferably proceeds in such a way that the piece immersed in aluminum is inserted into the mold while it is warm and the magnesium is poured in during a period of time in which the aluminum adhering to the immersed body is still liquid. With the good alloyability of aluminum and magnesium, however, it is also possible to bring the adhering aluminum back into solution after its solidification by the cast magnesium in a short time and thus to achieve the same composite casting effect as with the still liquid aluminum coating. This fact gives the process the advantage over the known casting process for aluminum that the objects to be cast, which have been pretreated by immersion, can be processed at any time after the pretreatment.

Although iron-aluminum compounds have only a very low solubility in magnesium, it is sufficient this low solubility apparently indicates a certain molecular connection between the Fe ^ Aljr layer applied to the iron and the to generate incoming magnesium. In any case, it turns out that there is a continuous metallic transition without disturbing oxide layers between the

909 560/371

_{the Fe x} Al ₁ , layer grown on iron and the cast magnesium.

Investigations of the mechanical properties of the bond produced in this way have shown that the achievable tensile strength of the layer is between 3 and 4 kg / mm ² , that is to say it is of the order of magnitude of the mechanical values that a bond between iron and aluminum has. The same is true for the shear strength.

Such other metals and alloys can also be used in place of iron with magnesium or a magnesium alloy on which by dipping in aluminum a layer of a compound of the aluminum with the corresponding one Can produce metal, such. B. with nickel.

Claims (2)

Patent claims: 1. A process for the production of composite castings made of magnesium or a magnesium alloy and a base body consisting of a metal or a metal alloy, in particular iron, which is coated with an intermediate layer, characterized in that the base body is briefly immersed in an aluminum melt to apply the intermediate layer and then magnesium or a magnesium alloy is cast onto the intermediate layer according to the general formula Me _x AL _1. 2. The method according to claim 1, characterized in that the casting of the magnesium takes place as long as the aluminum layer adhering to the workpiece has not yet solidified. Considered publications:
German Patent Nos. 247 780, 336 219;
U.S. Patent No. 2,455,457;
ATZ, 1953. CS 909 560/371 6.