JPH0196358A - Composite molybdenum plate and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a composite Mo plate having excellent impact resistance and high temp. deformation resistance by subjecting a composite ingot in which high pure Mo and Mo contg. specific amounts of La or La2O3 are laminated to high working and furthermore subjecting it to heating and coarsening treatment. CONSTITUTION:Each one layer or more of a pure Mo layer having >=99.95% purity and not contg. small amounts of elements to be added and a dope Mo layer contg. 0.1-1.0wt.% La or La2O3 and the balance consisting of Mo are combined. The composite ingot obtd. by this method is worked at >=80% total working ratio for its thickness. The work is then heated at least at the recrystallization temp. and is subjected to a coarsening treatment. By this treatment, the pure Mo layer shows a disk-shaped structure, and on the other hand, the dope Mo layer shows interlocking structure.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a molybdenum plate used for shell structural materials, high temperature reactors, boats for nuclear fuel sintering, materials for nuclear fusion reactors, materials for electron tubes, etc. Regarding the manufacturing method.

[Conventional technology]

Generally, molybdenum plates manufactured by powder metallurgy are made of pure molybdenum.

The recrystallization start temperature of this molybdenum plate is 1000°C. Therefore, a molybdenum plate made of molybdenum is 1
When used at temperatures above 000° C., there is a problem in that the plate becomes brittle due to the growth of recrystallized particles and is easily deformed under high-temperature loads. Therefore, as a molybdenum material that compensates for the above-mentioned drawbacks, a method has conventionally been used in which molybdenum is strengthened by adding various dopants.

[Problem that the invention seeks to solve]

However, conventional doped molybdenum materials require a high processing rate in the manufacturing process and have poor processability.

Furthermore, when used at high temperatures, the recrystallized structure is controlled by the arrangement of the dopant, so the recrystallized structure becomes long in the rolling direction and short in the direction perpendicular to the rolling direction. Therefore, when used in a manner that places a load on the short recrystallized structure, it has the disadvantage that it easily deforms.

On the other hand, by selecting the crystal grain structure of a molybdenum plate with a purity of 99.95% or more, a method is being used to create a plate with excellent high-temperature strength that has restrictions on the direction of use. However, it has the disadvantage that it easily deforms under large loads.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, it is a technical object of the present invention to provide a molybdenum plate that is easy to use and has a small amount of deformation even when subjected to loads under high temperature conditions, and a method for manufacturing the same.

[Means for solving problems]

According to the present invention, the ingot serving as the starting material for producing a molybdenum plate is, for example, 0.1% or more to 1.0%
% or less of lanthanum or lanthanum oxide;
It is formed from a combination of one or more layers of each of the two types of layers, including a pure molybdenum layer made of molybdenum with a purity of 99.95% or more.

Next, the ingot with this multilayer is
Hot forging, rolling, or a combination thereof is performed at a total processing rate of 0% or more.

Next, on the molybdenum plate made of this fibrous structure,
A coarsening treatment is performed by heat treatment at a temperature higher than the recrystallization temperature to recrystallize the crystal grains and release internal strain.

At this time, the pure molybdenum layer with a purity of 99.95% or more has a disk-like structure with an average diameter of 10 mm to 150 nm because there is no effect of suppressing grain growth due to dopants or impurities.

On the other hand, in the doped molybdenum layer doped with lanthanum, the dopant is arranged along the rolling direction, so grain growth in the thickness direction is suppressed, so the layer does not become coarse in the thickness direction, and rolling It exhibits a so-called interlocking structure that extends along the direction.

That is, a composite molybdenum plate is obtained, which is formed by an interlocking layer that is dispersion-strengthened by lanthanum oxide grains and a layer that has a disk-like structure that is less likely to cause grain boundary sliding without directionality.

Therefore, a high-quality molybdenum plate material with very little deformation even when exposed to high temperatures can be obtained.

Here, the addition amount of lanthanum oxide in the doped molybdenum layer containing lanthanum oxide was set to 1.0% or less because if the addition amount exceeds 1.0%, the amount of lanthanum oxide evaporated during sintering increases. This is because the pure molybdenum layer with a purity of 99.95% will be contaminated and the formation of a disk-like structure in the pure molybdenum layer with a purity of 99.95% in the crystal grain coarsening process will be hindered.

The reason why the content is set to 0.1% or more is that if O is less than 1%, the effect of lanthanum as a doping agent is weak, and formation of a sufficient interlocking layer cannot be expected.

〔Example〕

Next, a composite molybdenum plate material according to an example of the present invention will be described with reference to the drawings.

First of all, the average particle size of 99.95% pure or more is 3 to 5 μm.
Pure molybdenum powder was prepared.

Next, each 0.01. 0.1. 0.5. 1.
Molybdenum oxide powder doped with 0% by weight of lanthanum oxide was subjected to hydrogen reduction to prepare doped molybdenum powder doped with lanthanum oxide and having an average particle size of 2 to 5 μm.

Next, a mold for molding the powder was prepared, and first, doped molybdenum powder doped with lanthanum oxide was filled and the powder was leveled so that it was parallel to the bottom of the mold.

Next, pure molybdenum powder with a purity of 99.95% or more was filled, and the same leveling operation was performed. Finally, the powder doped with lanthanum oxide is again filled, leveled and worked, and a pressed body is formed using a hydraulic press at a pressure of 2 tons/cIII, and sintered at 1900°C for 5 hours in a hydrogen stream. An ingot having a 3N structure and having a thickness of about 30 m1 was obtained.

This ingot was heated at a maximum temperature of 1300° C., hot forged, and rolled repeatedly while gradually lowering the heating temperature, followed by warm rolling and cold rolling to obtain a molybdenum plate with a thickness of 2 times.

Next, this plate was subjected to grain coarsening treatment at 2250° C. in a hydrogen stream, and then test pieces of 2% weight x 20 mm x 15 Q mm were cut from the final rolling direction and the direction perpendicular to the final rolling direction. Using these specimens 1 to 4 according to the present invention and other comparison specimens 5 to 8 of similar size, a span of 10
Q +n with loads of 500g and 1000g, 1800
A deformation test was conducted at ℃ for 10 hours, and the amount of deformation was compared. Incidentally, the deformation test was conducted in the manner shown in FIG.

Here, the test pieces used for comparison are Plate 8, which is made of molybdenum with a purity of 99.95% and has a disk-shaped grain structure that is effective in high-temperature deformation resistance, and Molybdenum with a purity of 0.1%.

Molybdenum plates 5 to 7 contain lanthanum oxide at a ratio of 0.5% and 1.0%.

In addition, FIG. 1 shows the concept of the structure of test pieces 1 to 4 according to the present invention and comparison test pieces 5 to 8.

V-no, lower j-white Table-1 *〉20 Grounded on the jig As a result, as shown in Table-1, the lantern was 0.1 to 1.
The composite molybdenum plates (1 to 4) according to the present invention formed by a molybdenum layer containing 0% and a molybdenum layer with a purity of 99.95% or more have a difference in deformation in the rolling direction and at right angles to the rolling direction. It is observed that the amount of deformation is smaller than that of Comparative Examples 5 to 8, and the amount of deformation is also smaller.

[Example 2] In the same manner as in Example 1, 0.1 and 0.5゜1, respectively.
．． A layer made of molybdenum with a purity of 99.95% is sandwiched between molybdenum layers containing 0% by weight of lanthanum oxide, and furthermore, the degree of working becomes 65%, 80%, and 93% in the final rolling. I prepared an ingot.

Next, the ingot is heated to a maximum temperature of 1300°C, and subjected to hot forging and hot rolling, as well as warm rolling and cold rolling, so that the degree of working becomes 65%, 80%, and 93%, respectively. A plate with a certain ratio was manufactured. From there, 2u
+x 2 Qmsx A 150 mm specimen was cut out.

Next, this specimen was subjected to crystal grain coarsening treatment at 2250° C. in a hydrogen stream. This test piece was applied with a span of 100 and a load of 10.
A deformation test was conducted at 1800° C. for 10 hours using 00g to compare the amount of deformation. The results are shown in Table-2.

Margin Table-2 below *〉20 Grounding on the jig As a result, as shown in Table-2, test pieces 2, 3.5, 6, and 8.9 with a processing rate exceeding 80% were more processed. It is recognized that the amount of deformation is smaller than that of test specimens 1 and 4.7 with a ratio of 65%.

〔Effect of the invention〕

As explained above, according to the present invention, 0.1% or more to 1%
．． An ingot formed of at least one doped molybdenum layer containing 0% or less lanthanum and at least one pure molybdenum layer having a purity of 99.95% or more is hot forged at a processing rate of 80% or more in the thickness direction. Alternatively, hot rolling, further warm rolling and cold rolling are performed to align the dopant of the doped molybdenum layer containing lanthanum oxide in the direction perpendicular to the plate thickness, and then heated to a temperature higher than the recrystallization temperature.
By performing the coarsening treatment, the doped molybdenum layer containing lanthanum oxide becomes an interlocking layer that is dispersed and strengthened by the lanthanum oxide particles, while the purity is 99%.
．． A 95% or more pure molybdenum layer forms a layer having a large disk-like structure with little slippage at grain boundaries.

Therefore, it is possible to provide a composite molybdenum plate with excellent usability that exhibits little deformation even under high-temperature loads, and a method for manufacturing the same.

[Brief explanation of the drawing]

1 to 8 in FIG. 1 are conceptual diagrams showing the following structure. 1 is a three-layer structure according to the present invention of a molybdenum layer containing 0.01% lanthanum oxide and a molybdenum layer with a purity of 99.95%; 2 is a molybdenum layer containing 0.1% lanthanum oxide and a purity of 9
Three-layer structure according to the invention of 9.95% molybdenum layer, 3 is a molybdenum layer containing 0.5% lanthanum oxide and purity 9
Three-layer structure according to the present invention of 9.95% molybdenum layer, 4 is a molybdenum layer containing 1.0% lanthanum oxide and purity 9
9.95% molybdenum layer three-layer structure according to the present invention, 5 is a structure of a molybdenum plate containing 0.1% lanthanum oxide as a comparative example, 6 is a molybdenum plate containing 0.5% lanthanum oxide as a comparative example 7 is the structure of a molybdenum plate containing 1.0% lanthanum oxide as a comparative example, and 8 is the structure of a molybdenum plate with a purity of 99.95% as a comparative example. FIG. 2 is a diagram showing an aspect of a high temperature deformation test. Figure 1

Claims (1)

[Scope of Claims] 1) A pure molybdenum layer with a purity of 99.95% or more and containing no trace additive elements, and a layer containing lanthanum or lanthanum oxide in a weight ratio of 0.1% to 1.0%, with the remainder being 1. A composite molybdenum board comprising at least one doped molybdenum layer made of molybdenum. 2) A composite molybdenum plate according to claim 1, wherein the pure molybdenum layer has a disk-like structure, and the doped molybdenum layer has an interlocking structure. 3) A pure molybdenum layer with a purity of 99.95% or more, which does not contain trace additive elements, and a weight ratio of 0.1% or more to 1.0%.
A preparation process of preparing a composite ingot formed by combining at least one layer of each of the following lanthanum or lanthanum oxide with a doped molybdenum layer with the remainder being molybdenum, and total processing of 80% or more with respect to the thickness of the ingot. A method for producing a composite molybdenum plate having excellent impact resistance and high-temperature deformation resistance, comprising a processing step of processing the workpiece at a high temperature and a coarsening step of heating the workpiece at a temperature at least at which it recrystallizes. .