JP2001271102A - Bulk forming method for nonequilibrium powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for bulk forming process of alloy powder having a nonequilibrium phase. SOLUTION: In this method, alloy powder is produced by a mechanical alloying method or a rapid solidifying method and having a nonequilibrium phase is mixed with metal powder, ceramics powder or the like. This powdery mixture is filled into a metallic pipe and is pressed and heated to produce a bulk form containing a dense nonequilibrium phase, and the obtained product is further subjected to roll forming together with the metallic pipe to produce a denser form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidification molding method for bulking an alloy powder containing a non-equilibrium phase. More specifically, the present invention relates to a technique for solidifying and forming a bulk of an alloy powder containing a non-equilibrium phase by heating the alloy powder while applying pressure.

[0002]

2. Description of the Related Art An alloy powder containing a non-equilibrium phase can be produced by a mechanical alloying method or a rapid solidification method. However, since the non-equilibrium phase is easily crystallized, its solidification molding is very difficult. In particular, it is difficult to produce a compact by solidifying and molding with the non-equilibrium phase remaining, because thermal energy cannot be used to promote bonding by diffusion.

[0003] A technique has been proposed in which a non-equilibrium phase alloy powder is filled in a stainless steel pipe and solidified and formed by rolling (sheath rolling technique). After degassing, it is necessary to completely seal both ends of the pipe, and there remains a problem in industrial use.

[0004]

Under these circumstances, the present inventors have made intensive studies to solve the problems of the above prior art in view of the above prior art. Filling the metal powder containing metal powder into a metal pipe and pressing it with a punch where the part in contact with the powder is larger than the inside diameter of the pipe and smaller than the outside diameter, while solidifying and molding by directly energizing and heating the powder, The present inventors have found that the molding can be carried out densely at a temperature below the formation temperature, and have completed the present invention. The present invention has been made to provide a method for easily solidifying and molding an alloy powder containing a non-equilibrium phase by press molding.

[0005]

The present invention for solving the above-mentioned problems comprises the following technical means. (1) After filling an alloy powder containing a non-equilibrium phase produced by a mechanical alloying method or a rapid solidification method into a metal pipe, a portion in contact with the powder is larger than the inside diameter of the pipe and smaller than the outside diameter using a punch. A method for molding a non-equilibrium powder, comprising solidifying and molding a powder by applying current while applying pressure. (2) After mixing metal powder with alloy powder containing non-equilibrium phase prepared by mechanical alloying method or rapid solidification method, fill the metal pipe and contact the powder with the inner diameter of the pipe or more and the outer diameter A method for molding a non-equilibrium powder, comprising solidifying and molding a powder by applying current while applying pressure using a smaller punch. (3) After mixing ceramic powder with alloy powder containing non-equilibrium phase produced by mechanical alloying method or rapid solidification method,
A method for forming a non-equilibrium powder, comprising filling a metal pipe and solidifying and forming the powder by energizing and heating while applying pressure using a punch whose portion in contact with the powder is at least the inner diameter of the pipe and smaller than the outer diameter. (4) An inorganic or organic fibrous substance is mixed with an alloy powder containing a non-equilibrium phase produced by a mechanical alloying method or a rapid solidification method, and then mixed into a metal pipe. A method for molding a non-equilibrium powder, comprising solidifying and molding by energizing and heating while applying pressure using a punch having an inner diameter or more and a diameter smaller than the outer diameter. (5) A method for molding a non-equilibrium powder, wherein the molded body produced by the method according to any one of (1) to (4) is densely molded by rolling together with a metal pipe.

[0006]

Next, the present invention will be described in more detail. The present invention deforms an alloy powder that crystallizes by applying heat together with a molding die (metal pipe) without applying heat, thereby applying a shearing force to the powder to promote bonding between the powders. And a bulk solidified molded body. As the alloy powder containing a non-equilibrium phase used in the present invention, a powder synthesized by a rapid solidification method or a mechanical alloying method can be used. Examples of these powders include, but are not limited to, aluminum alloys and magnesium alloys manufactured by a single roll method, iron alloys manufactured by an atomizing method, and titanium alloys manufactured by a mechanical alloying method. The powder does not need to be composed only of the non-equilibrium phase, and the non-equilibrium phase and the equilibrium phase may be mixed. The non-equilibrium phase generally refers to a phase that becomes an equilibrium phase by heating, such as an amorphous phase or a quasicrystalline phase. The size of the alloy powder is not particularly specified, but generally a powder of 1 mm or less is preferable.

[0007] The alloy powder containing the non-equilibrium phase is filled into a metal pipe. Although a filling method is not particularly specified, a filling method using vibration or a filling method using a press or a hydrostatic pressure can be used for densely filling the pipe. The material of the pipe is not particularly specified, but a material which is deformed by pressurization and has conductivity can be used. Generally, pipes of stainless steel (SUS304), mild steel, titanium, aluminum, etc. can be used.

The alloy powder containing the non-equilibrium phase includes metal powder,
Ceramic powder or inorganic or organic fibrous materials may be mixed. Preferably, for example, tungsten powder, tantalum powder, yttria powder, titanium boride powder, carbon fiber and the like are exemplified. As a mixing method, low-energy mixing such as wet mixing or mortar mixing can be used. Although the mixing amount is not particularly specified, mixing of 30% by volume or less is preferable. If it exceeds 30% by volume, the pressure required for deformation increases, and the load on the device increases.

The molding temperature must be as high as possible but not higher than the crystallization temperature of the alloy powder containing the non-equilibrium phase. Care should be taken in the vicinity of the crystallization temperature of the alloy powder containing the non-equilibrium phase because crystallization occurs depending on the holding time even at a temperature lower than the crystallization temperature. For example, a mechanically alloyed Ti—Si alloy having a crystallization temperature of 550 ° C. is 480 ° C.
Crystallization for 20 minutes. When crystallization occurs, local heat generation occurs, and cracks occur in the molded body.

It is necessary to use a molding punch having a portion in contact with the powder having a size smaller than the outer diameter of the metal pipe and larger than the inner diameter. In the present invention, it is important to use a punch whose portion in contact with the powder is larger than the inner diameter of the pipe and smaller than the outer diameter. If the punch is larger than the outer diameter of the metal pipe, no deformation of the metal pipe occurs, and the densification of the powder does not proceed. Also, punches smaller than the inner diameter are the same as in conventional press molding, and powder containing a non-equilibrium phase is not densified. Only when the size of the portion in contact with the powder is smaller than the outer diameter of the metal pipe and larger than the inner diameter, the pipe is deformed into a barrel shape and a shear force acts on the powder. Generally, a punch having a truncated conical tip can be used. Preferably, a carbide-shaped (WC-10% Co) frustoconical carbide punch is used, but is not limited thereto.

The apparatus used for molding is not particularly specified, but a pressure molding apparatus using electric current as a heating mechanism can be used. Specifically, a discharge plasma sintering machine or a pulse current sintering machine can be used. The pressing force at the time of molding is not particularly specified, but by forming the tip of the punch into a truncated cone shape, a large molding force can be applied to the powder. In solidification molding of a powder containing a non-equilibrium phase, it is desirable to apply a pressure of 200 MPa or more to the powder.

Although there is no particular limitation on the pressurizing method, pressurization by a hydraulic press or a mechanical mechanism can be used. However, since heating is performed by energization, a jig used for pressurization must have conductivity, and a metal jig is preferable.

The heating atmosphere is not particularly specified, but it is preferable to use a vacuum atmosphere or an inert gas atmosphere so that the surface of the powder containing the non-equilibrium phase is not oxidized.

The compact obtained by the present invention is a bulk compact containing a non-equilibrium phase, and can further destroy remaining pores by rolling to obtain a dense compact having a density of 95% or more. it can. Rolling needs to be performed with the compact placed in a metal pipe, and a general rolling mill can be used. Rolling is preferably performed at room temperature, but can be performed under heating at or below the crystallization temperature of the alloy powder containing the non-equilibrium phase.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 7.4 g of titanium powder (special grade reagent manufactured by Wako Pure Chemical) and 2.6 g of silicon powder (special grade reagent manufactured by Wako Pure Chemical) were alloyed with amorphous phase by mechanical alloying treatment for 200 hours. A powder was made. The obtained powder has an inner diameter of 4 mm and an outer diameter of 6 m.
A pipe made of stainless steel (SUS304) having a height of 3 mm and a height of 3 mm was filled with a press and solidified and formed in a vacuum using a discharge plasma sintering apparatus. The punch used was a carbide (WC-10% Co) frustoconical carbide punch having a portion in contact with the powder having a diameter of 5 mm and a tip having a slope of 45 °. Heating to 350 ° C. below the crystallization temperature of about 500 ° C.
Sintering was performed by holding for 3 minutes. In addition, the pressing force in the part which contacts a powder was 800 MPa.

The metal pipe was deformed into a barrel shape, and a molded product was produced. The resulting compact had a thickness of 2 mm and contained approximately the same amount of amorphous phase as the powder.

Example 2 A melted Al-15 atomic% Cr powder was quenched by a single roll method and pulverized to produce a powder containing quasicrystals. This powder was mixed with 2% by volume of carbon fiber (20 μm diameter) in a mortar, and then filled into a stainless steel (SUS304) pipe having an inner diameter of 4 mm, an outer diameter of 6 mm, and a height of 3 mm by pressing, and spark plasma sintering. It was solidified and molded in a vacuum using an apparatus. The part of the punch that comes into contact with the powder is φ5m
m with a 45 ° gradient at the tip (WC-1
A 0% Co) frustoconical carbide punch was used. The sintering was performed by heating to 350 ° C. below the crystallization temperature of about 400 ° C. and holding for 3 minutes. In addition, the pressing force in the part which contacts a powder was 800 MPa.

The metal pipe was deformed into a barrel shape, and although a part of the metal pipe was pressed against the molded body, a dense molded body was obtained. The obtained molded body was a bulk body having a thickness of about 2 mm and containing quasicrystals.

Example 3 A molten La-25 at% Ni-20 at% Al alloy was quenched and then pulverized to produce an alloy powder containing an amorphous phase. After 5 atomic% TiB2 powder was mixed with the obtained alloy powder in a mortar, the inner diameter was 4 mm, the outer diameter was 6 mm,
A 3 mm high stainless steel (SUS304) pipe was filled with a vibrator and solidified and formed in a vacuum by a discharge plasma sintering apparatus. The part of the punch that contacts the powder is φ
Carbide with 5mm and 45 ° gradient at the tip (WC
A −10% Co) frustum-shaped carbide punch was used. The sintering was performed by heating to 250 ° C. below the crystallization temperature of about 300 ° C. and holding for 5 minutes. In addition, the pressing force in the part which contacts a powder was 500 MPa.

The metal pipe was deformed in a barrel shape, and a dense compact was obtained. Although the obtained compact had a slight decrease in the amorphous phase, the compact had an amorphous phase surrounding the TiB2 particles.

Example 4 4.4 g of iron powder (atomized powder) was mixed with 5.6 g of titanium powder (reagent made by Wako Pure Chemical Industries), and a powder containing an amorphous phase was synthesized by a mechanical alloying method for 400 hours. 5% by mass of yttrium oxide powder is mixed with the obtained powder in a mortar, filled into a titanium pipe having an inner diameter of 4 mm, an outer diameter of 6 mm, and a height of 5 mm, and solidified in a vacuum by a discharge plasma sintering apparatus. did. The punch is a carbide (W
C-10% Co) was used.
The sintering was performed by heating to 320 ° C. below the crystallization temperature of about 400 ° C. In addition, the pressing force in the part which contacts a powder was 800 MPa.

The metal pipe was deformed in a barrel shape, and was pressed against the molded body. Although the surface of the obtained molded body was dense, pores remained slightly near the center. However, the amorphous phase remained in the molded body, and the yttrium oxide particles were also uniformly dispersed.

Example 5 A Ti-40 atomic% Fe alloy produced by a rapid solidification method was mixed with 10
It was pulverized for 0 hour, filled into a stainless steel (SUS304) pipe having an inner diameter of 3 mm, an outer diameter of 6 mm, and a height of 5 mm, and solidified and formed in a vacuum using a pulse current sintering apparatus. The punch used was a super hard (WC-10% Co) super hard punch having a shape contacting with the powder and having a diameter of 5 mm and a 45 ° tip. 320 with a crystallization temperature of about 400 ° C or less
Sintered by heating to ° C. In addition, the pressing force in the part which contacts a powder was 800 MPa.

The metal pipe was deformed in a barrel shape, and a dense compact containing an amorphous phase could be obtained. The compact was pressed against a metal pipe and could be rolled at room temperature to reduce the thickness of the compact by 10%.
The obtained rolled material was further densified than the compact, and also contained an amorphous phase.

[0025]

As described above in detail, the present invention relates to a method for bulk molding of non-equilibrium powder. According to the present invention, 1) the method for bulk molding of non-equilibrium material of the present invention can be used. Alloy powders containing non-equilibrium phases such as amorphous and quasicrystals that could only be produced in the form of powders and ribbons can be processed into bulk compacts, and the superior mechanical and chemical properties of the non-equilibrium phases 2) In addition, a bulk body containing a non-equilibrium phase can be further processed into a member with a complicated shape by rolling or forging, expanding the field of industrial application. can do,
3) Unlike the conventional alloy development in which the number of alloying elements is increased, the material obtained in the present invention controls the constituent phases to improve its properties, and is an alloy that is rich in recyclability and environmental compatibility. Effects such as the achievement of development can be achieved.

Claims (5)

[Claims] After filling a metal pipe with a non-equilibrium phase-containing alloy powder produced by a mechanical alloying method or a rapid solidification method, a punch having a portion in contact with the powder that is larger than the inside diameter of the pipe and smaller than the outside diameter is formed. A method for molding a non-equilibrium powder, comprising solidifying and molding a powder by applying and heating while applying pressure. 2. After mixing a metal powder with an alloy powder containing a non-equilibrium phase produced by a mechanical alloying method or a rapid solidification method,
A method for forming a non-equilibrium powder, comprising filling a metal pipe and solidifying and forming the powder by energizing and heating while applying pressure using a punch whose portion in contact with the powder is at least the inner diameter of the pipe and smaller than the outer diameter. 3. A ceramic pipe is mixed with an alloy powder containing a non-equilibrium phase produced by a mechanical alloying method or a rapid solidification method, and then filled into a metal pipe. A method for forming a non-equilibrium powder, comprising solidifying and forming a powder by heating while applying pressure using a punch having a smaller outer diameter. 4. An inorganic or organic fibrous substance is mixed with an alloy powder containing a non-equilibrium phase produced by a mechanical alloying method or a rapid solidification method, and then the mixture is filled into a metal pipe. A method for molding a non-equilibrium powder, comprising solidifying and molding by energizing and heating while applying pressure using a punch having a diameter equal to or greater than the inner diameter of the pipe and smaller than the outer diameter. 5. A method for molding a non-equilibrium powder, wherein the compact produced by the method according to any one of claims 1 to 4 is compacted together with a metal pipe by rolling.