阅读说明：本技术 一种钛铝粉末复合棒材及其制备装置 (Titanium-aluminum powder composite bar and preparation device thereof ) 是由 方爽 魏振伟 兰博 李凯 姜涛 于 2020-05-29 设计创作，主要内容包括：本发明是一种钛铝粉末复合棒材及其制备装置,本发明技术方案利用了粉末材料良好的流动性,一个阶梯变化的变形量作用下,粉末颗粒之间的孔隙完全消失,达到全致密化,与此同时外层金属与内层金属通过过度组织形成一个整体,实现粉末构件固化-组织-成形一体化。相比于粉末轧制法和喷射沉积法,工艺流程大幅缩短,成本降低,从而制备出组织致密且具有细小再结晶组织。(The invention relates to a titanium-aluminum powder composite bar and a preparation device thereof. Compared with a powder rolling method and a spray deposition method, the process flow is greatly shortened, the cost is reduced, and therefore the prepared material has a compact structure and a fine recrystallized structure.)

1. The titanium-aluminum powder composite bar is characterized in that: the bar is in a layered structure from the core to the outside, the core is a cylinder of metal titanium, the outer layer is an annular metal aluminum layer, then an annular metal titanium layer, and the like, so that the titanium-aluminum composite bar is formed.

2. The titanium aluminum powder composite bar according to claim 1, wherein: the core part and the outward layered structures are both made of metal aluminum powder and metal titanium powder.

3. The titanium aluminum powder composite bar according to claim 1, wherein: the core and the outward layered structure are a total of four layers.

4. The titanium aluminum powder composite bar according to claim 1, wherein: the diameter of the core is the same as the thickness of the layers outward of the core.

5. An apparatus for preparing the titanium aluminum powder composite bar of claim 1, wherein: the device comprises a curing cavity and a forming cavity, wherein the two parts are connected together and coaxially and horizontally placed, and the device comprises:

the curing cavity comprises an annular upper cavity (12) and an upper pressure head (15), the upper pressure head (15) is sleeved in the upper cavity (12) and is in transition fit, and the rear end of the upper cavity (12) is connected with an annular first-stage extrusion die (11);

the rear end of the primary extrusion die (11) is a forming cavity which is sequentially a middle die cavity (10), a secondary extrusion die (5) and a lower die cavity (7), and a columnar lower pressure rod (6) is sleeved in a central hole of the lower die cavity (7) and is in transition fit;

the curing cavity and the forming cavity are arranged on a base (13) through a support (3), and a left hydraulic station (14) and a right hydraulic station (9) are respectively arranged in front of and behind the base (13) and provide hydraulic actuation for each part of the curing cavity and the forming cavity through hydraulic pipes (1);

heat insulation cotton (4) is arranged among the upper die cavity (12), the first-stage extrusion die (11), the middle die cavity (10), the second-stage extrusion die (5) and the lower die cavity (7) of the components of the curing die cavity and the forming die cavity and is fixedly connected through a lock catch ring (16).

6. The apparatus of claim 5, wherein: the two-stage extrusion die (5) and the bracket (3) at the bottom of the lower die cavity (7) are arranged on a slide rail (8) on a base (13) and can independently perform horizontal movement along the axial direction.

7. The apparatus of claim 5, wherein: the inner hole of the secondary extrusion die (5) is conical, and the difference between the maximum inner diameter and the minimum inner diameter is 1/20 of the length of the secondary extrusion die (5).

8. The apparatus of claim 5, wherein: the curing cavity and the forming cavity are made of steel materials with breaking strength exceeding 2000 MPa.

Technical Field

The invention relates to a titanium-aluminum powder composite bar and a preparation device thereof, belonging to the technical field of hot working.

Background

In the temperature range of 700-850 ℃, the specific strength of the TiAl alloy is obviously higher than that of common titanium alloy, nickel-based superalloy and other materials, the TiAl alloy casting is firstly applied to an engine, for example, the TiAl alloy is applied to a low-pressure turbine of a GEnx engine in the GE company rate of America, and the structural mass of each stage of low-pressure turbine is reduced by 45.5 kg. The TiAl alloy has low plasticity of as-cast structure, and can effectively refine the structure and reduce the component segregation degree through forging, extrusion, rolling and other hot processing, thereby improving the comprehensive mechanical property of the alloy. The titanium-aluminum bimetal composite bar takes aluminum alloy as the metal on the inner side of the tube as a stress layer, and a layer of titanium alloy is covered on the outer side of the tube as a protective layer. And the cost can be saved to a great extent by the bimetal compounding, so that the aim of lightening the pipe is fulfilled, and the bimetal compounding is highly emphasized by some countries in recent years and is used in the fields of aviation, military armor and the like.

The processing method of the metal laminated composite material is various, and the methods aiming at the powder metallurgy material generally comprise a powder rolling method and a spray deposition method. The powder rolling method comprises two methods: one is that powder is loosely spread on a base metal strip blank, and then the bimetal composite material is formed by powder rolling and sintering; the other is to use two hoppers to supply powder simultaneously, roll the powder into a bimetal powder strip blank, and then further sinter and roll the bimetal powder strip blank to obtain the bimetal composite material. This method is characterized by a long cycle time and is generally used for the production of panel-shaped components. The jet deposition method is characterized in that molten liquid metal flows out from a flow guide pipe at the bottom of a crucible under the action of air pressure or dead weight to form a stable metal liquid flow, when the metal liquid flow passes through an atomizer, the metal liquid flow is dispersed into an extremely fine metal liquid particle jet flow by high-pressure inert gas, part of small particles in the jet flow are condensed and solidified, part of large particles can keep a liquid phase and are in a solid state and a semi-solid state, the jet flow is told to be sprayed to a lower substrate material to generate impact, condensation and solidification, most of the jet flow forms a deposition layer, and the deposition layer is attached to the substrate. The limitations of this method are that the deposit forms an excessively thick liquid phase layer on the top, which will exfoliate into a soil-like cast structure, making thick-walled components difficult to produce, and in addition, the dimensional accuracy of the deposited layer is low due to uneven distribution of the material in the metal jet.

Disclosure of Invention

The invention provides a titanium-aluminum powder composite bar and a preparation device thereof aiming at the defects in the prior art in China, and aims to improve the production efficiency of the titanium-aluminum bimetal composite bar and the microstructure of the titanium-aluminum bimetal composite bar.

The purpose of the invention is realized by the following technical scheme:

the titanium-aluminum powder composite bar is of a layered structure from the core to the outside, the core is a cylinder of metal titanium, the outer layer is an annular metal aluminum layer, then an annular metal titanium layer, and the like, so that the titanium-aluminum composite bar is formed.

In one implementation, the core and the outward layered structures are made of metal aluminum powder and metal titanium powder.

In one implementation, the core and outward laminate structure together are four layers.

In one implementation, the core has the same diameter as the thickness of the outward layers.

The technical scheme of the invention provides a device for preparing the titanium-aluminum powder composite bar, which comprises a curing cavity and a forming cavity, wherein the curing cavity and the forming cavity are connected together and coaxially and horizontally arranged, and the device comprises:

the curing cavity comprises an annular upper die cavity 12 and an upper pressure head 15, the upper pressure head 15 is sleeved in the upper die cavity 12 and is in transition fit, and the rear end of the upper die cavity 12 is connected with an annular primary extrusion die 11;

the rear end of the first-stage extrusion die 11 is a forming die cavity which sequentially comprises a middle die cavity 10, a second-stage extrusion die 5 and a lower die cavity 7, and a columnar lower pressing rod 6 is sleeved in a central hole of the lower die cavity 7 and is in transition fit with the central hole;

the curing cavity and the forming cavity are arranged on a base 13 through a bracket 3, a left hydraulic station 14 and a right hydraulic station 9 are respectively arranged in front of and behind the base 13 to provide hydraulic actuation for each part of the curing cavity and the forming cavity through a hydraulic pipe 1;

the heat insulation cotton 4 is arranged among the upper die cavity 12, the first-stage extrusion die 11, the middle die cavity 10, the second-stage extrusion die 5 and the lower die cavity 7 of the components of the curing die cavity and the forming die cavity and is connected and fixed through a locking ring 16.

In one embodiment, the secondary extrusion die 5, the support 3 at the bottom of the lower die cavity 7, are mounted on slide rails 8 on a base 13 and are capable of independent horizontal movement in the axial direction.

In one implementation, the internal bore of secondary extrusion die 5 is tapered with the difference between the largest internal diameter and the smallest internal diameter being 1/20 times the length of secondary extrusion die 5.

In one implementation, the curing cavity and the forming cavity are made of steel materials with breaking strength exceeding 2000 MPa.

The technical scheme of the invention has the characteristics and beneficial effects that:

the titanium-aluminum powder composite bar provided by the invention is obtained based on the research on the plastic forming technology of the powder metallurgy bimetal composite bar, mainly aims at the technical current situation that the period is long and the microstructure distribution uniformity is poor in the domestic metal laminar composite material processing method at present, and the basic principle of the preparation is that the good fluidity of the powder material is utilized, the pores among powder particles completely disappear under the action of a deformation amount with step change, the full densification is achieved, and meanwhile, the outer layer metal and the inner layer metal form a whole through a transition structure, and the solidification-structure-forming integration of the powder component is realized. The transition structure comprises steel sheaths when the metal powder is formed between the layers. Compared with a powder rolling method and a spray deposition method, the process flow is greatly shortened, the cost is reduced, and therefore the prepared material has a compact structure and a fine recrystallized structure.

Compared with the preparation technology of powdery high-temperature alloy annular components at home and abroad, the technical scheme of the invention has the advantages that:

(1) by utilizing the good fluidity of the powder, the solidification-forming integration of the components is realized in the forming process of the bimetal composite bar, and the forming efficiency is improved;

(2) in the process of drilling the powder into the sheath, the powder is subjected to the action of temperature and pressure to continuously plastically deform, and the accumulated denaturation can meet the energy requirement of the whole process of combining powder particles from an interface to recrystallization nucleation and growth;

(3) the process flow is simplified, the development period is shortened, the material utilization rate is improved, and the manufacturing cost of the component is reduced.

Drawings

FIG. 1 is a schematic structural diagram of an extrusion die in the technical scheme of the invention

FIG. 2 is a schematic view of the internal structure of the composite bar according to the technical solution of the present invention

Detailed Description

The technical solution of the present invention will be further described with reference to the following examples:

referring to the attached drawings 1-2, the preparation method of the titanium-aluminum powder composite bar comprises the following steps:

step one, powder blank preparation

The powder blank comprises a powder sheath and powder, wherein the powder sheath is formed by sleeving four stainless steel cylindrical pipes with the same height and different diameters, so that four independent cavities are formed, metal titanium powder, metal aluminum powder, metal titanium powder and metal aluminum powder are sequentially filled from inside to outside, the core and the outward laminated structure are four layers, and the diameter of the core is the same as the thickness of each outward layer;

step two, preparing the extrusion device

The device comprises a curing cavity and a forming cavity, wherein the two parts are connected together and coaxially and horizontally placed, and the device comprises:

the curing cavity comprises an annular upper die cavity 12 and an upper pressure head 15, the upper pressure head 15 is sleeved in the upper die cavity 12 and is in transition fit, and the rear end of the upper die cavity 12 is connected with an annular primary extrusion die 11;

the rear end of the first-stage extrusion die 11 is a forming die cavity which sequentially comprises a middle die cavity 10, a second-stage extrusion die 5 and a lower die cavity 7, and a columnar lower pressing rod 6 is sleeved in a central hole of the lower die cavity 7 and is in transition fit with the central hole;

the curing cavity and the forming cavity are arranged on a base 13 through a bracket 3, a left hydraulic station 14 and a right hydraulic station 9 are respectively arranged in front of and behind the base 13 to provide hydraulic actuation for each part of the curing cavity and the forming cavity through a hydraulic pipe 1;

the heat insulation cotton 4 is arranged among the upper die cavity 12, the first-stage extrusion die 11, the middle die cavity 10, the second-stage extrusion die 5 and the lower die cavity 7 of the assembly of the curing die cavity and the forming die cavity and is connected and fixed through a lock catch ring 16;

the secondary extrusion die 5 and the bracket 3 at the bottom of the lower die cavity 7 are arranged on a slide rail 8 positioned on a base 13 and can independently perform horizontal movement along the axial direction;

the inner hole of the secondary extrusion die 5 is conical, and the difference between the maximum inner diameter and the minimum inner diameter is 1/20 of the length of the secondary extrusion die 5.

The curing cavity and the forming cavity are made of steel materials with breaking strength exceeding 2000 MPa;

sliding the powder blank and the upper pressure head 15 into the upper die cavity 12 together, and positioning the left end face of the lower pressure rod 6 at the extrusion port of the lower die cavity 7;

step three, preheating powder and a die

Heating the metal powder and the surrounding die assembly to 300-500 ℃, and carrying out heat preservation, wherein the heat preservation time is calculated according to the following formula 1:

T_{time of heat preservation}＝(L_{Diameter of upper die cavity}+L_{Wall thickness of upper compression ring}× 2) × 1.7min/mm equation 1

Step four, powder solidification

After the heat preservation time is over, the upper pressure head 15 starts to act, the speed is kept between 17mm/s and 20mm/s until the pressure reaches 50-200MPa, and then the upper pressure head 15 stops acting to obtain a solidified prefabricated blank;

step five, extrusion molding

Heating the middle die cavity 10 and the solidified prefabricated blank in the upper die cavity 12 to 500-700 ℃, extruding the solidified prefabricated blank obtained in the fourth step into the middle die cavity 10 from the upper die cavity 12 through the action of an upper pressure head 15, keeping the speed between 17mm/s and 20mm/s and the extrusion ratio between 1: 1 and 2: 1, and obtaining a completely solidified powder titanium-aluminum composite component;

and continuously pushing the completely solidified powder titanium-aluminum composite component to pass through a preheated secondary extrusion die 5 for extrusion, wherein the preheating temperature is 700-1000 ℃, the speed is kept between 17mm/s and 20mm/s, and the extruded component penetrates out of a central hole of a lower die cavity 7, so that the preparation of the titanium-aluminum powder composite bar is completed.