US2294389A - Electrical resistance alloy - Google Patents

Description

Sept. 1, 1942. R. s. DEAN EIAL ELECTRICAL RESISTANCE ALLOY 2 Sheets-Sheet 1 Filed Nov. 6, 1939 onQDo9mu om mm 9 h: 8 mu ow hw ob .Q on mm 8 mm QQS Qmkmsk 59m m \w 9 x MwZEQWMM 9 YAW ATTORNEY5 Sept. 1, 1942. I R. s. DEAN ETIAL ATTORNEY 5 NV OR. Re a/admit p /z BY Claw/ace 7/3106 6246/2500 k $2 amino 1E my MQE. mm? N Patented Sept. 1, 1942 UNITED STATES PATENT OFFICE ELECTRICAL RESISTANCE ALLOY Application November 6, 1939, Serial No. 303,008

7 Claims.

This invention relates to electrical resistance alloys having high electrical resistance and a low temperature coefllcient of resistance. It relates more in particular to the alloys of manganese, nickel and copper which have theseproperties.

In the drawings accompanying the specification:

Fig. 1 is a ternary diagram of the manganesenickel-copper system showing the relationship between composition and electrical resistance;

Fig. 2 is a similar diagram showing the temperature coeflicient of electrical resistance as affected by the composition.

We have found that alloys of manganese, nickel and copper, within a certain composition range, possess electrical resistance of more than 170x ohm/cm. and a temperature coeificient of less than i1.0 10- ohms/ohm/deg. C. The relation between electrical resistance and composition in the ternary system manganesenickel-copper appears clear from Fig. l. The lines show equal electrical resistance as indicated. The unit of electrical resistance is 10- ohm/emf. Thus, along the line marked I10, the electrical resistance is 170 X 10- ohms/cm}.

Fig. 2 shows the relation between composition and temperature coefficient of electrical resistance in this same ternary system. The lines show equal temperature coeflicient of electrical resistance in which the unit is 10- ohms/ohmI- deg. C.

It will be clear that these results of our investigations disclose a range of compositions which have a high electrical resistance and a very low temperature coeflicient. By noting where the lines of Figs. 1 and 2 bisect each other, a composition may be determined where the desired combination of properties are to be found.

We prefer to employ these alloys in the state produced by quenching from a temperature of about 900 degrees C. and cold working to suitable wire or other shape for practical use. The results from which Figs. 1 and 2 were plotted were obtained on alloys treated in this way. As to most of these alloys, when they are reheated to a temperature of approximately 450 degrees C., the very low temperature coeflicient is no longer found in the alloys of high resistance. This is illustrated by the following examples:

To secure the results desired, various quenching temperatures may be used. Good results may Alloy composition Resist- Tempera- Resist- Temperaanoe cold ture ance ture. worked coeflicient 450 C. coefficient Mn Ni Cu compassed within the range of high electrical resistance and low temperature coeflicient are valuable. The following table illustrates tensile of the alloys in the cold worked condition:

Composition Tensile Rockwell strength 0 per square Mn Ni Cu inch These alloys posses corrosion resisting properties which make them especially useful for electrical resistance purposes.

These alloys in the range up to 10% nickel possess unusually high vibration damping capacity. When measured at very low stresses, the damping capacity is of the order of 2%. The alloys of high resistance possess a coefiicient of linear expansion of more than 20 10- cm./cm./deg. C.

Thus, it will be seen that in addition to unusual electrical properties, the alloys of our invention have desirable mechanical properties which make them eminently suitable for the production of electrical resistance elements of various types. Just as the combination of electrical properties desired may be determined by reference to composition, so the composition may be modified to meet mechanical requirements to a considerable extent, although it will be understood that as the number of properties considered is increased, there is less likelihood of obtaining the maximum of any particular characteristics, and some compromise may be necessary.

In addition to the selection of composition for determining properties, the treatment, particularly the heat treatment, of the alloys will have a hearing. The alloys of our present invention may be used as either low temperature or high temperature resistance alloys, particularly when they are employed in the soft condition.

A study of the ternary diagrams and an analysis of the properties as compared to composition, shows that with from about 45% and to manganese, and substantially independently of the relative proportions of copper and nickel, the resistance value is or above, with a particular valuable range occurring when the manganese is between about 55% and about 75%. So far as the relationship of copperto nickel is concerned, the manganese being constant, the relationship is fairly orderly as the shape of the lines in Fig. 1 illustrates.

on one side of the pseudo-binary line, that is, on 4 the side where the manganese is greater than the nickel. Indeed, generally it may be stated that in the direction of increased manganese. the temperature coemcient of electrical resistance tends to be lower and the electrical resistance itself higher. The most valuable properties, therefore, are found in the relatively high manganese range previously discussed.

What we claim is new and desire to protect by Letters Patent of the United States is:

1. An electrical resistance element composed of an alloy of manganese, nickel and copper having more than 55% 75% manganese, from 2 /2% to 35% nickel, balance copper, said element having an electrical resistance of not less than 170 10- ohms/cm said alloy being quenched from a temperature between about 900. degrees C. and the melting point thereof and cold worked.

manganese and less than consisting of approximately 2. An electrical resistance element composed of an alloy of manganese, nickel andcopper having a composition of between manganese and 75% manganese having an electrical resist ance of between 170 to 200 10 ohms/cm. and a temperature coeificient of electrical resistance not greater than 1.0 0- ohms/ohm/deg. 0.. said alloy falling within the region of low temperature coefficient of electrical resistance as identified in Fig. 2, and being quenched from a temperature between .about 900 degrees C. and the melting point thereof and cold worked.

3. An electrical resistance element consisting of an alloy of manganese, nickel and copper,

wherein the proportion of manganese is between about 25% and about and wherein the temelements copper perature coefficient of electrical resistance is less than 0 10- ohms/ohm/deg. C., said alloy falling within cient of electrical resistance as identified in Fig. 2, and being quenchedfrom a temperature between about 900 degrees C. and the melting point thereof and cold worked.

4. An electrical resistance element identified on the attached drawings falling substantially at the points where lines showing at least 150 10 ohms/cm. in Fig. 1 would cross lines on Fig. 2 showing a temperature coefficient of electrical resistance not greater than 1 10- ohms/ohm/deg. C., said resistance consisting of 45 to 75% manganese and at least one of the and nickel, said alloy being temperature between about 900 the meltingpoint thereof and quenched from 9. degrees C. and cold worked.

5. A resistance element comprising an alloy of approximately manganese, approximately 7%% nickel and approximately 27%% copper, said alloy being quenched from a temperature between about 900 degrees C. and the melting point thereof and cold worked.

6. A resistance element comprising an alloy 65% manganese, and balance nickel and copper, the proportion of copper being greater than the proportion of nickel, the nickel constituting at least 2%% of the alloy, trical resistance of at least 170x10- ohms/cm. and a temperature coefllcient of electrical resistance not greater than 1x10 ohms/ohm/cmF, said alloy being quenched from a temperature between about 900 degrees C. and the melting point thereof and cold worked.

7. An electrical resistance element, having a low temperature coeflicient of electrical resistance, comprising an alloy quenched from a temperature of about 900 degrees C. and cold worked,

said alloy consisting of about 60% to manthe region of low temperature coefli the resistance element having an elec-

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