US1855436A - Magnesium base alloys - Google Patents

Description

Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE BOBERT.TEOHAS WOOD, 01' LAKEWOOD, OHIO, ASSIGNOB TO AIEBIOAN EAGNESIUH GO BPORATIOIE-OI' PITTSBURGH, PENNSYLVANIA, A. CORPORATION OF NEW YORK BASE llo Drawing.

alloys of thiscla'ss containing tin and man- 'ganese. I 5 In my copending application filed concurrently herewith, there is described and claimed a magnesium base alloy containing v or without other allo ing elements, such as manganese, the alloy ing characterized by certain advantages therein disclosed. In the first of these alloys manganese is an essential constituent and in the second its presence is m optional althou h desirable.

The object 0 this invention is the provision of a commerciall operable and economical'method of intro ucingmanganese into magnesium base alloys such as those disclosed an in the above mentioned copending applications, and other alloys containin tin. Several methods have alrea y been disclosed for introducin manganese into magnesium base allo s. or example, the-metal 39 in the form of finely divided particles may be added directly to the molten magnesium. The latter may not safely be heated to more than 800 C. in ordinary atmosphere and even at this tem rature considerable care 'is necessary and t e reaction with the atmosphere is severe. At best not more than a trifling amount-of manganese can be alloyed in this way, probably not more than 0.02 per cent.

about 1100 C. in an inert atmosphere, for instance, argon or helium, and a substantially greater amount ofmanganese will alloy but this method is economically prohibitive.

The manganese may be alloyed with aluminum and this aluminum-manganese alloy added to molten magnesium as a rich alloy. This method has the disadvantage that all an uent alloys made by the addition of n this r ch alloyto magnesium will contain The molten magnesium may be heated to Application filed December 88, 1980. Serial No. 504,429.

aluminum and aluminum may not be desired in the particular magnesium alloy be compounded. Also the amount of manganese which can be added in this wa is limited.

Where the presence of aluminum in the magnesium alloy is not required or desirable but where manganese and tin are desire the method which I have invented and herewith disclose is of a special advantage.

In carrying out my method in the preferred manne first prepare a tin manganese-rich allo I have found that if finely divided metallic manganese be added to molten in at about 500 C. very little alloying takes place even if the temperature is maintained for a relatively long time, but if the temperature is raised to between 500 C. and 1000 C. appreciable alloying of the manganese and tin occurs within a. fairly short time. By this method I have obtained alloys of 80 Eer cent tinv and per cent manganese. y raising the temperature to between 1000 C. and 1600 C. I have produced alloys of per cent tin and 50 per cent manganese. A simple yet desirable precaution to prevent oxidation of the tin at elevated temperatures consists in sprinkling. charcoal on the surface of the molten metal. This in no way interferes-with the process and may be skimmed ofl before the alloy is .poured 1nto the usual notch bar molds.

Having prepared the proper manganeserich alloy I add the necessary amount thereof, with or without additions of pure tin, to the molterfinagnesium. By this method the desired amount of manganese is easily alloyedwith the magnesium.

As a. practical example of the application of the principles herein outlined, I have heated a pot of molten tin to about 1100 C.

and then added. finely divided metallic mangan'ese, The melt was covered with powder charcoal and maintained at this temperature for about 30 minutes, being stirred fairly regularly. It was then allowed to cool,

poured into notch. bars and a chemical analysis made. This showed a manganese content of 21.06 r cent and a tin content of 78.94 per cent. y going to higher temperatures the content of alloyed manganese can be further increased, if desired.

I claim- 1. In compounding a magnesium base al- 5 loy containing tin and man anese, adding a tin-manganese alloy to mo ten magnesium.

2. The method of compounding a magnesium base alloy containing tin and manganese, which comprises heating tin to more 10 than about 500 (3., adding manganese thereto, maintainingthe temperature of the melt until the manganese has substantially dissolved, and adding a suitable proportlon of the resulting tin-manganese al oy to molten 5 magnesium.

.In testimony whereof I hereto acflix my signature. 7

ROBERT THOMAS WOOD.