JPS59116356A - Molybdenum alloy - Google Patents

Abstract

PURPOSE:To obtain an Mo alloy with a high recrystallization temp. and superior strength at high temp. by adding a small amount of Zn and a very small amount of B to Mo and by alloying them. CONSTITUTION:Powders of Mo, Zn and B and C are blended together in a prescribed ratio, and they are mixed by means of a magnetic pot roll. The mixture is press-molded under 3,000kg/cm<2> pressure. The molded body is sintered by calcination at 1,830 deg.C in a hydrogen atmosphere for 7hr, and two such sintered bodies are joined together and alloyed by a vacuum arc melting method using a consumable electrode to form an Mo alloy ingot contg. 0.02-0.5% Zr and 5- 100ppm B. The ingot is worked into a thin plate by hot forging, hot rolling and cold rolling. An Mo alloy with a high recrystallization temp. and superior strength at high temp. is obtd. and is used as a heat resistant material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a molybdenum alloy that has excellent high-temperature strength and a high recrystallization temperature.

[Technical background of the invention and its problems]

Molybdenum alloys have excellent high-temperature stability in vacuum, inert, and reducing atmospheres, so they are used as a variety of heat-generating materials.Recently, molybdenum alloys are used for applications in the nuclear field, such as the reactor walls of fusion reactors. is expanding.

However, after a molybdenum alloy is heated above its recrystallization temperature, its ductility at room temperature becomes poor, and brittle fracture is more likely to occur at grain boundaries, resulting in a decrease in its strength.

As a solution to this problem, an alloy containing molybdenum and a small amount of vanadium is known. This improves the strength of the alloy by dissolving vanadium in molybdenum, and also cleans the grain boundaries by reacting vanadium with grain boundary impurities (such as oxygen) present in the grain boundaries. There are also alloys known in which the deoxidizing effect is improved by adding a small amount of carbon.

However, in recent years, as the properties required of molybdenum alloys have become stricter, there has been a strong desire to develop molybdenum alloys that have a high aged crystallization temperature and excellent high-temperature strength.

[Purpose of the invention]

The object of the present invention is to provide a molybdenum alloy with a novel composition that has a high recrystallization temperature and high high-temperature strength.

[Summary of the invention]

The molybdenum alloy of the present invention contains zirconium (Zr) 0
．． 02-0.5% by weight, boron (B) 5-1001)p
m, the remainder being molybdenum (MO).

In the IIJI Q alloy of the present invention, Zr forms a solid solution with MO, and also combines with oxygen, carbon, etc. in the base metal, and is dispersed in the base metal, thereby improving the mechanical strength of the alloy, especially its high temperature It is a component that not only increases strength but also increases recrystallization temperature and suppresses coarsening of crystal grains. The effect of Zr can be seen from 0.02 times bleaching, but
If the amount exceeds 0.5% by weight, the rate of increase in recrystallization temperature will decrease and the processability of the resulting alloy will deteriorate. Preferably 1; tO, 1 to 02 times.

B is a component that greatly contributes to cleaning grain boundaries and prevents coarsening of crystal grains after recrystallization. If the B content is less than 5 ppm, the grain boundary cleaning effect will not be sufficient, and if it exceeds 1100 ppm, Mo2B will precipitate and become coarse, leading to embrittlement of the alloy. Ideally 20~s
opprn.

The MO alloy of the present invention can be manufactured as follows. That is, Mo with a particle size of 3 to 20μ7n.

After weighing a predetermined amount of Zr I B powder and thoroughly mixing them in a mixer such as a porcelain pot mill, the obtained mixed powder is made into a kufu.

Shape it with a cloth etc. After this compact is sintered according to a conventional method, the obtained sintered compact is arc melted in a vacuum to form an alloy.

At this time, it is useful to add a small amount of carbon, preferably 300 ppm or less, in addition to MOIZrlB, since this can further promote the deoxidizing effect of carbon and the effect of B during arc melting.

However, it should be noted that when the amount of residual carbon exceeds 500 ppm, the workability of the alloy deteriorates significantly.

The alloy ingot thus obtained can be subjected to predetermined processing such as hot forging and hot rolling to be processed into various shapes for practical use.

[Embodiments of the invention]

1) Alloy production MO, Zr, BIC powder (average particle size 6 μ+?z)
were blended in a predetermined ratio, mixed using a porcelain pot roller, and then formed into a molded product using a lano press at a pressure of 3000 kg/cnt2.

This molded body was fired in a hydrogen atmosphere at 1830C for 7 hours to form a sintered body with a diameter of 25 mm and a length of 300 trvn. Two pieces of this material were joined together and alloyed using a consumable electrode vacuum arc melting method to form an ingot with a diameter of 50 mrv and a length of 200 mm.

The composition of the obtained MO alloy is shown in the table.

In the table, sample numbers 1 to 6 are alloys of the present invention, and sample number 7 is a comparative example.

The above-mentioned ingot was subjected to conventional hot forging, hot rolling, and cold rolling to obtain a material having a thickness of 1 mm.

2) Measurement of properties and results The plates of each sample number were annealed at various temperatures in a hydrogen furnace for 1 hour, then the plates were cooled to room temperature, and the Witzkers hardness (Hv) of these plates was measured. . Figure 1 shows the fallen fruit.

For the plate materials of sample numbers 1 to 5, read the temperature at which the HV of iL shows an intermediate value between the processed material and the fully annealed material from Figure 1, and calculate that temperature (semi-softening temperature) and the Zr content of the plate material. Figure 2 was obtained by plotting the relationship between

Next, each plate material was observed under a microscope at a magnification of 200, and the number of recrystallized grains present in a unit area (0,0625+n+n2) was measured, and the results are shown in FIG. 3 as a relationship with the annealing temperature.

7. For each sample number 1 to 50 plates. The relationship between the amount of r and the recrystallized grain size was read from FIG. 3 and is shown in FIG. 4.

Then, for the plate materials of sample numbers 2, 4 and 7, 1400
After annealing at t: for 1 hour, the tensile strength (MPa) was measured at each of these temperatures, and the results are shown in FIG.

As is clear from FIG. 1, the Mo alloy of the present invention has high hardness, that is, a high recrystallization temperature. It's a trench.
It can be seen from FIGS. 2 and 3 that as the amount of Zr increases, the semi-softening temperature increases, that is, the recrystallization temperature increases and the recrystallized grains become smaller.

Moreover, as is clear from FIG. 5, the alloy of the present invention has a higher 71 strength than pure Mo.

〔Effect of the invention〕

The MO alloy of the present invention has a high recrystallization temperature and high high-temperature strength, so it is highly useful as a high-temperature heating material.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the annealing temperature and Witzkars hardness of the board used in the examples, Figure 2 is a diagram showing the relationship between semi-softening temperature and Zr content, and Figure 3 is the relationship between annealing temperature and recrystallization. The relationship diagram with particle size, Figure 4 is 7. Relationship diagram between r amount and recrystallized grain size,
FIG. 5 is a diagram showing the tensile strength at each temperature. Funeral 41 ~ R t Zr amount (% of hair) - Figure 5 8. Shape ('C) - Procedural amendment document January 24, 1958 Kazuo Wakasugi, Commissioner of the Patent Office 1, Indication of the incident 1981 Special Fraud Application No. 224016 2 Name of the invention Molybdenum Alloy 3 Relationship with the person making the amendment Name of the special fraud applicant (307) Tokyo Shibaura Electric Co., Ltd. (Name) 4 Agent

Claims (1)

[Claims] Zirconium 002-05 heavy i' [L% + boron 5
A molybdenum alloy characterized in that 1100pp and the remainder are molybdenum.