JPH0242888B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention can be used as an element for a magnetostrictive sensor used in a load cell, a force meter for measuring pressure, tension, etc., an element for a magnetostrictive vibrator for generating ultrasonic waves, or an element for a structure using magnetostriction such as a magnetostrictive bimetal. The present invention relates to a useful palladium-cobalt alloy having large magnetostriction. In recent years, in the field of force measurement using metal magnetostrictive materials, with rapid progress in automation, miniaturization, and labor-saving of various processes and devices, improvements in sensor reliability, higher precision, and miniaturization have been made. has become in demand. As a magnetostrictive material that can meet these diverse needs, firstly, it has large magnetostriction and can provide a large signal output, and secondly, it has good cold workability and can be formed into the desired shape. Thirdly, it is necessary that the amount of strain be expressed in a low magnetic field. Conventionally, magnetostrictive materials used for force measurement include Ni, Fe-Ni alloy, Fe-Si alloy, and Fe-
Metals and alloys such as Al alloys are used depending on the purpose. The saturation magnetostriction value of these magnetostrictive materials is about Δl/l≒-35×10 ^-6 (l = length) of Ni or a smaller value, and some alloys have poor cold workability. be. In the present invention, it has been discovered that with a specific composition of palladium-cobalt alloy, large magnetostrictive properties far exceeding the magnetostrictive values of conventional magnetostrictive materials can be developed through simple heat treatment or processing. The purpose of this is to make it easy to cold work and have a magnetostatic strain of -40 to -170×10 ^-6.
The object of the present invention is to provide a novel material which has a value of . The alloy of the present invention consists of more than 80% palladium and less than 92% palladium and less than 20% cobalt and more than 8% by weight, contains a small amount of impurities, and has an absolute magnetostriction saturation value of 40 × 10 ^-6 or more. A palladium-cobalt alloy for a magnetostrictive actuator is characterized by the following. In addition, the method for producing the alloy of the present invention involves hot working and cold working for alloys consisting of more than 80% palladium and less than 92% palladium and less than 20% cobalt and more than 8% cobalt, and containing a small amount of impurities. Magnetostrictive operation characterized by forming a thin plate into a desired shape, heating it in air, inert gas, or vacuum at a temperature of 900°C or higher and lower than the melting point for 1 minute or more, and then slowly cooling it at a desired rate. The method for manufacturing palladium-cobalt alloys for body use. Next, a method for producing the alloy of the present invention will be explained. First, palladium and cobalt having the above composition range are melted in an ordinary melting furnace in air, an inert gas, or a vacuum, and then sufficiently stirred to form a uniform molten alloy. Next, this is poured into a mold to create an ingot, and this is further poured into a mold.
After performing hot working such as forging, rolling, or swaging at a temperature of 900°C or higher and 1400°C or lower, the material is cold worked at room temperature or above room temperature to form a material in a shape suitable for the intended use. This molded body is heated to 900℃
The product is heated and maintained at a temperature above the melting point or below, for example 1000° C., for 1 minute or more, usually for about 1 hour, and then slowly cooled to form a product. Next, examples of the present invention will be described. Example Palladium and cobalt were melted using a Tammann furnace (electric resistance furnace) in an alumina crucible with an inner diameter of about 10 mm while passing argon gas, and after stirring the molten metal well, it was sucked into a quartz tube with an inner diameter of about 3 mm and cooled. . Next, it was swaged at room temperature to form a round bar with a diameter of 2 mm, and a sample approximately 10 cm in length was cut from this round bar. Then, it was heated at 1000°C for 1 hour and then cooled at a rate of 100°C/hour to prepare a measurement sample. The longitudinal magnetostriction of the sample in the longitudinal direction was measured using an optical lever type device having two rotors. On the other hand, an ingot made by pouring the molten alloy into an iron mold was hot forged and cold rolled into a thin plate of about 0.2 mm. An annular sample with an inner diameter of 33 mm and an outer diameter of 45 mm was punched out from this thin plate, and was subjected to the same heat treatment as the round bar sample to obtain a sample for measuring dynamic magnetostriction characteristics. The dynamic magnetostriction characteristics were measured using an ordinary Maxwell Bridge type device. Table 1 shows the longitudinal magnetostriction values of the present invention example at an applied magnetic field Hex=1.2 kOe and the saturation magnetostriction values of the three conventional alloys.

[Table] Figure 1 shows the weight proportions of palladium and cobalt among the measurement results: 57%: 43%, 77%: 23%,
The relationship between the longitudinal magnetostriction value and the applied magnetic field Hex is shown for alloys with compositions of 80%:20%, 82%:18%, and 90%:10%, and for nickel as a comparative example. These results show that the longitudinal magnetostriction of the alloy of the present invention is greater than that of nickel in all compositions, especially in the case of 82% palladium and 18% cobalt.
It can be seen that the value of the alloy exhibits a large value of -167×10 ^-6 , which is about 5 times that of nickel, in a magnetic field of 1100 Oe. FIG. 2 shows the longitudinal magnetostriction values when applied magnetic fields of 100 Oe, 200 Oe, and 1200 Oe are applied to various alloys within the composition range of the present invention. That is, cobalt 15-20 in any applied magnetic field.
It is the largest in %. FIG. 3 shows the relationship between the maximum value of the ratio of longitudinal magnetostriction to the applied magnetic field (λ/Hex) _nax of the alloy of the present invention and the concentration. where (λ/Hex) _nax is cobalt content
−1.1 to −1.5×10 ⁻⁶ Oe ⁻¹ for 10–20% alloy;
Is it comparable to that of Nickel, or
The value is higher than that. In particular, an alloy with a cobalt content of 18% has a value of -1.53×10 ^-6 Oe ^-1 , which is approximately 1.5 times as large as that of nickel. Note that in a magnetostrictive vibrator, the value of the electromechanical coupling coefficient k, which is a figure of merit, is also important, so the results of measuring this for an alloy of 82% palladium and 18% cobalt are shown in FIG. As shown in the figure, k of the alloy of the present invention is small when the DC deflection magnetic field is about 35 Oe or less when compared to nickel, but when it exceeds that, it becomes larger than that of nickel. As explained in detail above, the alloy of the present invention can also be used as an element for a magnetostrictive vibrator. In addition, the alloy of the present invention not only exhibits a very large saturation magnetostriction value, but also consists of a single solid solution of face-centered cubic crystals, so it is extremely easy to cold or hot work, and it can be molded into any shape. It is possible to obtain. This is also a great advantage when manufacturing thin plates such as magnetostrictive vibrators and magnetostrictive bimetals. Finally, in the present invention more than 80% palladium
The reason why it is limited to 92% or less is that if the palladium content is 80% or less or 92% or more, the absolute value of the magnetostatic strain saturation value becomes smaller than the desired value of 40×10 ^-6 or more.

[Brief explanation of drawings]

Figure 1 is a characteristic curve diagram showing the relationship between longitudinal magnetostriction and applied magnetic field for palladium-cobalt alloys, and Figure 2 is a graph showing the relationship between longitudinal magnetostriction and applied magnetic field for palladium-cobalt alloys.
Figure 3 is a characteristic curve diagram showing the relationship between longitudinal magnetostriction and alloy concentration in an applied magnetic field of 1200 Oe. Figure 3 is a characteristic curve diagram showing the relationship between (λ/Hex) _nax and alloy concentration of palladium-cobalt alloy. The diagram shows palladium 82
%, is a characteristic curve diagram showing the relationship between the electromechanical coupling coefficient and the DC deflection magnetic field of an alloy with 18% cobalt.

Claims (1)

[Claims] 1 Consisting of palladium exceeding 80% and not exceeding 92% and cobalt being below 20% and not exceeding 8% by weight, containing a small amount of impurities, and having an absolute value of magnetostriction saturation value of 40×
A palladium-cobalt alloy for use in magnetostrictive actuators, characterized by having a hardness of 10 ^-6 or more. 2. An alloy consisting of more than 80% palladium and less than 92% palladium and less than 20% cobalt and more than 8% by weight, and containing a small amount of impurities, is made into a desired shape such as a wire rod or thin plate material by hot working and cold working. A palladium-cobalt alloy for a magnetostrictive actuator, which is then heated in air, in an inert gas, or in a vacuum at a temperature of 900°C or higher and lower than the melting point for 1 minute or more, and then slowly cooled at a desired rate. Manufacturing method.