US2270191A - Magnesium base alloy - Google Patents

Description

Patented Jenfls, 1942 UNITED STATES PATENT OFFICE MAGNESIUM BASE ALLOY John C. McDonald, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application October 4, 1940, Serial No. 359,683

3 Claims.

' such as high yield and tensile strengths.

Commercially pure magnesium has been used only in a. limited way as a structural material because of its relatively low strength, although ggsilight weight is a highly desirable character- It is, therefore, the principal object of the invention to provide a magnesium base alloy which possesses the light weight characteristic of magnesium and at the same time is endowed with superior strength characteristics.

Other objects and advantages will be apparent as the description of the invention proceeds.

My invention resides in the discovery that a magnesium base alloy containing from 0.01 to 4 per cent of platinum, the balance being magnesium, possesses the aforementioned properties of high tensile and yield strengths. The term magnesium used herein and in the appended claims is intended to include magnesium containing the ordinary impurities that are found in commercially'pure metal, such as traces of nickel, iron, copper, and silicon. While the properties of high yield and tensile strengths are manifest over the entire range of composition indicated, I have found that in general the preferred combination of properties is-found in those alloys containing from 0.1 to 2.5 per cent of platinum; A preferred composition having exceptionally high yield and tensile strengths is one containing about 1 per cent of platinum.

The following table, listing some of the prop- A erties of rolled sheet metal made from my new binary alloy and comparing these properties with those of magnesium, illustrates the improvement in yield strength and tensile strength of my new alloy over that of magnesium. The magnesium used in preparing the new alloy and for the purposes of comparison was obtained by sublimlng commercial magnesium.

Table Nominal compo- Annealed Cold rolled sition in percent I Yield Tensile Yield Tensile i l strengthin strengthin strengthin sttengthin lbs/sq. in. lba/sq. in. lbs./sq. in. lba/sq.

The properties set forth above under the term "annealed were obtained by first rolling the specimens at a temperature of from 650 to 750 F. and thereafter annealing them at various temperatures of from 400 to 800 F; The properties' selected for the table were those of the annealed specimens ,which exhibited the maximum elongation. The properties set forth under the term "cold rolled were obtained by subjecting the specimens which had been first hot rolled at a temperature of from 650 to 700 F. to additional rolling in the cold state. The properties selected for the table were those of the cold rolled specimens which'showed the greatest yield strength while having an elongation of at least 1 per cent in 2 inches.

A comparison of the properties listed in the above table shows that the yield strength and tensile strength of my new alloy are markedly 2o superior to those of magnesium in both the an healed and the cold'rolled state. The improvement shown in the above example is exhibited throughout the range of the alloying ingredient indicated.

The new alloy will be found to be most useful in making large castings, forgings, and the like protected from' oxidation by suitable flux.

I claim: '1. A magnesium base alloy containing from 0 0.01 to 4 per cent of platinum and characterized by a substantial improvement in at least one of 40 the properties ductility, yield strengthfand' tensile strength as compared to magnesium without the platinum. v

' 2. A magnesium ,base alloy containingfrom 0.01 to 4 per cent of platinum, the, balance being magnesium.

3. A magnesium base alloy containing'from 0.1 to 2.5 per cent of platinum,the balance being magnesium.

JOHN C. MCDONALD.