Using TZM Alloy to Produce Titanium Isothermal Forging Material

Titanium alloy has some special requirements on isothermal forging, for example, there are some special requirements on mold temperature, pressure and dwell time. During isothermal forging the mold temperature should be at 850~950 ℃ and pressure should be control at 100~120 MPa. Besides, the dwell time should be at 5~15 minutes, and based on the above requirements, commonly used nickel-base superalloy, insoluble metals and their alloys (TZM alloy), ceramic material, such as silicon nitride, silicon carbide and so on as titanium isothermal forging material. The experiment found that compared to the performance of other material TZM alloy has more favorable advantages. TZM alloy not only has good temperature resistance and high strength property, but the die service life also has a strong advantage.

Using TZM alloy as sophisticated forgings materials during isothermal forging, there may be has some crack happening in forging die to cause damage, and forging die damage may be caused by the following reasons:
1. The forging die happen some local plastic deformation and dimensional change;
2. Effected by the lubricant and protective gas, the embedding of material cause wearing;
3. The cracks concentrated on the place where the local stress is highly.

In order to prevent forging die early damage, understanding the carrying capacity before the crack spread of TZM alloy forging die, understanding of the conditions of forging die appeared, have important significance for judging the operation reliability and evaluation the forging die service life.

The cracks in the forging die are often unavoidable, so to slow the pace of cracks expansion has a certain influence on the service life of the mold. It was found that if the dwell time is too long, there will have a certain impact on crack formation and expansion. So isothermal forging pressing time should be as short.On the other hand, forging die at preheating and cooling will produce high thermal stress, causing cracks. In order to avoid large thermal stress, people should pay special attention to preheat uniformity.

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Surface Oxidation and Segregation of TZM Alloy

Segregation phenomenon refers to the constituent elements of the alloy uneven distribution in the crystallization. The experiment found that TZM alloy added element segregation occurs at ultrahigh vacuum and at different temperature ranges. Titanium segregation starts from 840 ℃ and zirconium segregation is beginning from 1100 ℃. Titanium's maximum temperature segregation is 1150 ℃ and zirconium is 1350 ℃. Higher than the above temperature, the surface concentration of titanium and zirconium are decreasing, and higher than 1400 ℃titanium will disappear the same surface. Segregation temperature is similar to the required temperature of these two elements diffuse to the molybdenum substrate. The temperature of segregation disappearance depends on the balance of the additional diffusion kinetics.

In TZM alloys, titanium and zirconium element has a great affinity for oxygen, so oxidation reaction with oxygen is easily. Stability of TiO2 and ZrO2 promotes the surface material to absorbent the oxygen, free standard enthalpy of formation of these two oxides is lower than MoO2, and both vapor pressure is smaller than MoO2. Thus, the surface oxygen can diffuse to the alloy and preferential oxidation with the additive of alloy producing oxides precipitate. TZM alloy samples after 1390 ℃ treatment, the alloy surface is covered with a large amount of oxide precipitation. After milling alloy surface, the inside oxygen precipitates content only one-tenth of alloy surface.

We can confirm TZM alloy surface oxidation by microstructure oxide precipitation tests of the alloy. The shape and form of oxide precipitates has big difference with carbide precipitate. In an oxidizing atmosphere, at 1200 ℃ alloy starts decarburization reaction, oxygen is gradually dissolved and the original oxide oxidation occurs.

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Properties and Applications of Molybdenum Copper Alloys

The main applications of molybdenum-copper alloy are closely related to its good properties.

1. Molybdenum copper (Mo-Cu) is often prepared as a heat sink and heat sink plate, mainly because molybdenum-copper alloy has excellent electrical and thermal conductivity properties.

2. Mo-Cu can also be used as instrument components. Because it has non-magnetic, low and adjustable thermal expansion coefficient, high elastic modulus, high thermal conductivity and other properties which can meet the requirements of some special instruments, so it widely be use as instrument components.

3.Melting point of Molybdenum is 2610℃and copper melting point is 1083℃, therefore molybdenum-copper alloy at room temperature and high temperature not only has good strength, and has a certain plasticity. When the temperature is higher than the melting point of copper, copper alloy will liquefy to play cooling effect. Therefore molybdenum copper alloy can be used as a special high-temperature materials used in aerospace and military fields, such as nozzle throat insert, electrical contacts and rockets, missiles, weapons and other high temperature components.

4. Molybdenum has high hardness and brittleness, it is more difficult to machine. After added copper into Mo-Cu alloy, hardness decreased, plastic increases, so molybdenum copper has good processing performance can be processed into a variety of complex shaped parts, which greatly expanded its field of application.

5. Mo-Cu also contents low gas and has good vacuum performance. First of all, the oxide of molybdenum and copper reduction is simple. Secondly, N, H, C and other impurities in molybdenum and copper remove easily, so it has good vacuum performance.

6. Mo-Cu not only has good thermal conductivity properties, and it also has high melting point, corrosion resistance, low thermal expansion and other properties. So it not only be used in high-voltage ceramic vacuum, used in the microelectronics industry becomes more and more popular , such as molybdenum copper is widely made integrated circuits and heat sink materials.

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Copper Molybdenum Copper Packaging Martial

Copper molybdenum copper (CMC) packaging material is kind of composite sandwich flat structure, which uses pure molybdenum as core material, double-sided coated with copper or copper dispersion strengthened.

Thermal expansion coefficient of this material is adjustable and it also has high thermal conductivity, excellent high temperature and other good performance, has been widely used in electronic packaging. CMC Material is metal matrix flat layered composite electronic packaging materials. The structure of this electronic packaging composite materials are stacked, generally divided into three layers.

The intermediate layer is a low expansion material layer and on both sides of the high electrical and thermal conductivity material layer. On the other hand, there are two, or four composite laminates of this material. Commonly use rolling composite method, plating composite method, explosive forming method and other processing method to produce. These materials have good thermal conductivity and low coefficient of expansion in the planar direction, and basically there are no dense problems, in addition, the processing cost of it is relatively low. For example, there can be continuous rolling to compounding produce rolls / Invar / Cu composite sheet, which can greatly reduce production costs and it also can be processed into 70um foil, widely used in the core layer PCB and lead frame material.

Because the CMC material has high theoretical thermal conductivity, coefficient of expansion and matched to Si, back in the 1990s, experts and scholars employed a in-depth study, the United States AMAX company and Climax Specialty Metals company use hot rolling complex method produced CMC composites, and applied for a patent, has been used in the electronic device B2 stealth bomber. CMC structure and CIC are the same as three-layer composite structure, but the hardness, tensile strength, heat and electrical conductivity much higher than the CIC, it is because the middle of the CMC is molybdenum plate, molybdenum and strength, electrical conductivity, and thermal conductivity are higher than Inar alloys.

CMC electronic packaging materials having excellent thermal conductivity and adjustment thermal expansion coefficient, currently is the preferred electronic packaging materials in high-power electronic components among domestic and international. Besides, it can match with Be0, Al203 ceramics, widely used in microwave, communications, aerospace, power electronics, high-power semiconductor lasers, medical and other industries. In addition, in microwave packaging and radio frequency field also extensive use CMC material as the heat sink material. In military electronic devices, it is often adopted as a highly reliable circuit board substrate material.

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Using Liquid Phase Method to Produce Molybdenum Disulfide

Liquid phase method including precipitation, hydrothermal and solvothermal method, different methods exist significant differences in process step, sulfide raw material consumption, waste and water emissions. The main features of the liquid phase method are low cost of production, large production yield, high purity and controllable form. Besides, molybdenum disulfide can be prepared in different functional requirements. However, the requirements of liquid phase method for raw materials requirement are high, and the resulting product is easy reunion.

Production molybdenum disulfide by precipitation method- Making molybdenum sulfide reacts with molybdenum salt to produce insoluble molybdenum trisulfide. Then after precipitation, pyrolysis or reduction can obtain molybdenum disulfide. Using precipitation to produce molybdenum disulfide, the reaction process is simple, easy operation, low cost, high yield, which is suitable for industrial production.

 Production molybdenum disulfide by Hydrothermal method- the reaction of hydrothermal method is happen in sealed special containers, under high temperature, pressure conditions and other conditions, and water-soluble molybdenum sulfide reacts with molybdenum disulfide salt formation in water to produce water-insoluble molybdenum-disulfide. This method can generate products directly, greatly reducing or avoiding the formation of hard agglomerates. What’s more, the hydrothermal method has shorter process steps, simple equipment requirement, easy operate, less sulfide material consumption, smaller particle size and other advantages. In addition, the obvious advantages of it are eliminating exhaust gas containing hydrogen sulfide.

Production molybdenum disulfide by Solvothermal method - This method is based on the hydrothermal method, but organic solvent instead of water. Due to the diversity of organic solvents, lower boiling point and different dielectric constant, polarity, viscosity, etc., depending on the different solvent system and the target product can design new synthetic routes, expanding the scope of application of the hydrothermal method.

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Ultra-fine Molybdenum Copper Powder

With the rapid development of science, technology and cutting-edge industries, especially the development of the electronics industry by leaps and bounds, put forward newer and higher requirements electronic packaging materials performance. Packaging materials are not only required to match the thermal expansion coefficient of the packaged device, but is required to have high thermal conductivity, non-magnetic, heat resistance, corrosion resistance and other special properties.

Molybdenum copper (Mo-Cu) alloy is a binary and mutually insoluble pseudo alloy and it has high melting point, high density, good electrical conductivity, good thermal conductivity, adjustment coefficient of expansion and other advantages. So it is widely used in aerospace, metallurgy, electric power, electronics and semiconductor industries, especially plays an important role in the electronics, semiconductor industry and pays close attention to all developed countries.

Producing ultra-fine molybdenum copper powder not only can refine powder size and powder will become more uniformity, so it can improve the density and organization uniformity. Ultra-fine powder can obtained molybdenum copper alloy which has near the theoretical density. Besides, the copper will distributed around and molybdenum evenly, forming the ideal network-like structure.

In order to find the optimum method for preparing ultra-fine molybdenum copper powder, using scanning electron microscopy and transmission electron microscopy studies the effects of different milling ways and different milling on molybdenum copper powder’s morphology and particle size.

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Cleaned Molybdenum Wire

Cleaned molybdenum wire is a surface clean, no graphite layer and molybdenum oxide layer molybdenum wire, which has a good high strength, conductivity, cutting speed, long life and other good properties. Cleaned molybdenum wire is usually applied in line cutting field, it usually as vacuum devices, heating elements, refractory matter of high temperature furnace and the parts for electric light source production. In addition, the cleaned molybdenum wire can also be used as a spray molybdenum wire, applied to the wear parts of the car, improving its mechanical wear.

Cleaned white molybdenum wire, using electrolytic cleaning or hydrogen sintering method to clean graphite coating on molybdenum wire surface and to make the surface bright and glossy. Electrolytic cleaning cleaned molybdenum wire method: this is a cleaning method which uses conducting medium to apply voltage on molybdenum wire and to clean molybdenum wire. And the molybdenum wire will as an electrode and immerse in electrolyte. Hydrogen sintering clean white molybdenum wire method: This method is mainly cleaning metal impurities on the surface of molybdenum wire. Firstly, putting molybdenum wire in vacuum furnace, heating vacuum furnace above 1400 ℃, repeated pass hydrogen into vacuum furnace to make the amount of hydrogen in the furnace reaches 500-10,000 microns, then remove the reaction products which produces by impurities on cleaned molybdenum wire surface and hydrogen.

Cleaned molybdenum wire applications and its performance has a certain relationship between the degree of processing, for example, un-annealed cleaned molybdenum wire and annealed molybdenum wire can as rods, hooks, mandrel and the electrodes applied to different areas, but the performances of them are different, for example, annealed cleaned molybdenum wire elongation is ≤8%; straightness is ≤20 / 200, tensile strength is 1200-2200MPa. On the other hand, un-annealed cleaned molybdenum wire elongation is ≥10%; straightness is ≤ 20/200; tensile strength is 700-1500MPa. The user can select different processing levels’ white molybdenum wire according to application.

Chinatungsten Online (Xiamen) Manu. & Sales Corp. has provided the following molybdenum wire types, such as high temperature molybdenum wire, doped molybdenum wire, straightening type molybdenum wire, high temperature cleaned molybdenum wire, straightening and doping type cleaned molybdenum wire, straightening type cleaned molybdenum wire, high temperature straightening type cleaned molybdenum wire, doped cleaned molybdenum wire and soft cleaned molybdenum wire.

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Molybdenum and TZM Alloy Plastic Processing

When stress of the metal exceeds the elastic limit, there will have plastic deformation occurs. Adjacent atomic planes have relative tangential motion. Besides, when the shear stress is large enough, the atomic will from the equilibrium position go into another equilibrium position. But when the external force disappear the atomic planes which after tangential motion can not move back to the original position, thus producing irreversible permanent deformation, that is, plastic processing.

Deformation resistance refers to a kind of ability for resistance plastic deformation. The metal material in order to maintain the original state, there will produce deformation resistance to resist deformation at certain of temperature, speed and deformation degree. From the microscopic point, the external forces make the distance between atoms to change resulting in an imbalance of attraction and repulsion. Molybdenum and TZM alloy in the rolling process will produce deformation resistance, and the main factors which influence the deformation resistance is material chemical composition, metallurgical properties, geometry, friction of deformation outer zone, material work hardening and the deformation zone of thermodynamic parameters.

Molybdenum and TZM alloy plastic processing method mainly includes rolling, extrusion, drawing, stamping, forging, die forging and the equipments include used include rolling mill, extrusion machines, stretching machines, punching machine, forging machines and rolling machine and so on. Molybdenum and TZM alloy only through plastic processing can obtain the desired shape such as wire, strip, rods, tubes and other products with customized shapes and can apply to different areas as well. The main plastic processing method of TZM or molybdenum rod is rolling and model rolling. On the other hand, the wire and tubes usually through stretching machine to produce, and the products of sheet, strip and foil mainly through rolling method.

Using rolling method for material plastic processing mainly puts metal blank in the gap of a pair of rotating rollers (the desired shape), through the compression of rotating rollers to decrease cross-section and to increase the length of the material, then to obtain high quality products. Rolling method is mainly used for the production of bar, sheet and tube. Using rolling mill can obtain good quality product, having low metal burning rate, high productivity, high degree of mechanization, and therefore it is widely used. Rolling can be divided into cold rolling and hot rolling.

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