JPH05320793A - High hardness intermetallic compound base alloy for casting - Google Patents

Abstract

PURPOSE:To provide a high hardness metallic material having superior corrosion resistance, castability, and grindability. CONSTITUTION:This alloy has a chemical composition consisting of, by atom, 7.0-9.5% Ti, 9.0-12.0% Si, 0.01-0.2% C, 0.1-3.0%, in total, of Hf and/or Zr, and the balance essentially Ni or further containing 0.1-3.0%, in total, of one or more elements among Ta, Al, Fe, Cr, Nb, Cu, and Mo so that the total content of Hf, Zr, Ta, Al, Fe, Cr, Nb, Cu, and Mo becomes <=3.0%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a high hardness, excellent corrosion resistance, and castability, and is suitable for casting, for example, based on a Ni ₃ (Si, Ti) intermetallic compound suitable as a material for watches. It concerns alloys.

[0002]

2. Description of the Related Art Conventionally, a case member for accommodating a timepiece body, which is composed of a timepiece member (a body, a glass edge, and a back cover)
Although stainless steel has been the mainstream, the timepiece-like members are generally manufactured by punching and subsequent milling, and it is also necessary to make small holes and threads. .. Therefore, a material having poor machinability causes severe damage to the tool and increases man-hours. Therefore, free-cutting stainless steel such as SUS303 steel is usually used.

However, in free-cutting stainless steel, S (sulfur) added to improve machinability acts as inclusions to impair the finish of polishing finish and cause cracking during punching. Therefore, it was not easy to stabilize the product quality.

Therefore, recently, in order to solve the above problems and reduce the cost, attempts have been made to manufacture a timepiece member by a precision casting method such as a die casting method or a lost wax method, and at the same time, punching cannot be performed. There is an increasing tendency to apply high hardness materials. This is because the application of the high hardness material has a good result in preventing the surface flaw of the product.

However, in the case of cast materials, castability, which has not been a problem in the conventional plastically worked materials, has a great influence on the quality of the finished product. Little material has been known that has corrosion resistance and polishing properties and exhibits good castability.

[0006]

From the above viewpoints, the present invention provides a number of high hardness materials having excellent corrosion resistance, castability, and polishability, which are suitable for, for example, timepiece members. It was completed based on the results of research conducted by the present inventors while conducting repeated tests. "Ti: 7.0-9.5%
(Hereafter,% representing the component ratio shall be atomic%), Si: 9.0 ~
12.0%, C: 0.01 to 0.2%, either or both of Hf and Zr: 0.1 to 3.0% in total, or further T
One or more of a, Al, Fe, Cr, Nb, Cu and Mo: 0.1 in total
Corrosion resistance, casting with a chemical composition of ~ 3.0% in a proportion such that the total content of Hf, Zr, Ta, Al, Fe, Cr, Nb, Cu and Mo is 3.0% or less, and the balance being substantially Ni. sex, excellent polishing property and has a high Ni ₃ (Si, Ti) for casting having a hardness greater characterized in providing an intermetallic compound based alloy ".

[0007]

The alloy according to the present invention can be produced by adjusting the components so as to have the above-mentioned chemical composition and melting it. However, this alloy is based on Ni ₃ (Si, Ti) which is an intermetallic compound. It has a very high hardness and a melting point of 1200-
Since it is a low melting point alloy with a low casting temperature of 1250 ° C and an excellent casting surface, it is suitable for die casting. Further, since it is a high Si alloy, a stable silicate film is formed on the surface, so that it exhibits excellent corrosion resistance and is suitable for use as a timepiece member and the like. Then, it shows good polishing property by comprehensive adjustment of components, and exhibits preferable surface texture after polishing.

The reason why the content ratios of the constituents in the alloy of the present invention are numerically limited as described above will be explained below.

A) Ti and Si combine with each other to maintain the crystal structure of the Ll ₂ type intermetallic compound and to ensure room temperature ductility, but when the Ti content is less than 7.0%. Or, if the Si content is less than 9.0%, the hardness of the alloy and the room temperature ductility are deteriorated. On the other hand, if the Ti content exceeds 9.5% or the Si content exceeds 12.0%, Ni ₃ Ti or Ni ₅ Si
₂ Precipitation of Ni ₁₆ Ti ₆ Si ₇ occurs and impairs the surface properties during polishing.

C) C has the effect of improving the mid- to high-temperature ductility in the atmosphere, but if its content is less than 0.01%, the desired effect due to the above-mentioned effect cannot be obtained, and cracking during casting occurs. Etc. will become a concern. On the other hand, if the C content exceeds 0.2%, the above effect cannot be expected due to the precipitation of the second phase.

D) Since Hf and Zr both have the same effect of improving the hot ductility of the alloy and are effective in preventing cracks during casting, either or both of them are added. .. However, if the total content of these is less than 0.1%, the desired effect due to the above-mentioned action cannot be obtained, while if the total content exceeds 3.0%, precipitation of the second phase occurs and the desired good results are obtained. It becomes difficult to secure a good surface texture.

E) Ta, Al, Fe, Cr, Nb, Cu and Mo All of these components have the effect of further improving the alloy characteristics, so one or more of them may be added if necessary. .. That is, Ta, Al, Fe, Cr, and Nb are particularly effective in increasing the hardness of the alloy, and increase the value of the product in the case of, for example, watches, etc., and also impair the corrosion resistance against sweat. Absent. Further, Cu and Mo are particularly effective for improving the corrosion resistance of the alloy, and addition of Cu and Mo does not impair the surface gloss. However, if the total content of these elements is less than 0.1%, the above effect is not remarkable, while on the other hand, if the content is excessive (total amount).
If it is added to more than 3.0%), the second phase is precipitated like Hf and Zr, and it becomes difficult to secure good surface properties.

As described above, Ta, Al, Fe, Cr,
Nb, Cu, and Mo are elements that cause the precipitation of the second phase, like Hf and Zr.
The total content of Zr, Ta, Al, Fe, Cr, Nb, Cu and Mo is 3.0.
% And below.

The high-hardness alloy for casting according to the present invention is particularly suitable as a timepiece member, but it goes without saying that it can be used for various other purposes requiring the above-mentioned performance.

[0015]

Example First, alloys having the chemical compositions shown in Table 1 were melted and a timepiece member was manufactured by the lost wax method and the die casting method. In addition, according to the material investigation of the member for the watch side after casting, it was found that this was Ni ₃ (Si, T) having the Ll ₂ type crystal structure.
i) It was confirmed that the alloy was based on an intermetallic compound.

[0016]

[Table 1]

Next, the "Vickers" of the obtained timepiece side member is obtained.
"Hardness", "corrosion resistance", "casting defect" and "surface properties after polishing" were investigated.
The artificial sweat specified in 1141-52 is kept at 40 ° C,
A method of visually observing the occurrence of surface pits when the timepiece member was immersed in this for 60 days and taken out. Further, the evaluation of casting defects was carried out by visually observing the occurrence of cracks, shrinkage cavities, wrinkles and the like. For the evaluation of the surface properties after polishing, the presence or absence of "unevenness" or "wrinkle" was visually judged.

From the results shown in Table 1, it can be confirmed that all the alloys of the present invention have high hardness and excellent corrosion resistance, castability, and surface properties after polishing.

[0019]

[Summary of Effects] As described above, according to the present invention, it is possible to provide an intermetallic compound-based alloy exhibiting excellent corrosion resistance, castability, polishability, and high hardness, and applied to timepiece members and the like. As a result, the quality and value of the product can be further improved, and industrially useful effects are brought about.

Front page continuation (72) Inventor Seiya Wada, 8-2 Honshiocho, Shinjuku-ku, Tokyo Inside the Technical Research Institute of Japan (72) Inventor Takayuki Takasugi 12-11 Nishihanaen, Aoba-ku, Sendai City, Miyagi Prefecture

Claims (2)

[Claims] 1. At atomic%, Ti: 7.0 to 9.5%, Si: 9.0 to 12.0%, C: 0.
01 to 0.2%, either or both of Hf and Zr: 0.1 to total
A high hardness alloy for casting, based on a Ni ₃ (Si, Ti) intermetallic compound, characterized in that it contains 3.0% and the balance consists essentially of Ni. 2. At atomic%, Ti: 7.0 to 9.5%, Si: 9.0 to 12.0%, C: 0.
01 to 0.2%, either or both of Hf and Zr: 0.1 to total
3.0%, one or more of Ta, Al, Fe, Cr, Nb, Cu and Mo: 0.1 to 3.0% in total for the above Hf, Zr, Ta, Al, Fe, Cr, N
b, Cu and Mo are contained in a ratio such that the total content is 3.0% or less, and the balance is substantially composed of Ni,
High hardness alloy for casting based on Ni ₃ (Si, Ti) intermetallic compound.