Sintering Of Titanium and Titanium Alloy Materials

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Titanium is a new kind of material with the advantages of low density, high specific strength, heat resistance and corrosion resistance. It weighs only half as much as iron, but its mechanical properties such as hammering and drawing are neck and neck with copper. Generally speaking, as the temperature decreases, the resistance of the metal will decline, but titanium is the opposite, the lower the temperature, titanium will become more and more rigid, and at the critical temperature will appear superconductivity phenomenon.

Titanium alloy and titanium are similar in nature to some extent, with the characteristics of small density and high strength, in addition to its excellent mechanical properties, corrosion resistance is strong. And its thermal strength is high, obviously better than aluminum alloy, at the same time at low temperature and ultra-low temperature its mechanical properties change little.

The sintering of titanium alloy powder is usually a solid phase diffusion method. When the titanium alloy is prepared by the mixed element method, it is found that the alloying elements in the titanium alloy may exhibit a transient liquid phase during sintering or provide a diffusion channel to promote the densification process, which is also called strengthening sintering.

The realization of the strengthening sintering process depends on three basic conditions, namely solubility criterion, segregation criterion and diffusion criterion. Generally, the matrix should be in the additive: have a large solubility, or form an intermediate compound, and the solubility of the additive in the matrix should be small.

During vacuum sintering, the additive can be precipitated out at the interface between powder particles, and it can be maintained throughout the sintering process. This precipitation enriched the additive by dispersing the contact surfaces between the powder particles. Therefore, it provides a channel for rapid diffusion of the matrix. This precipitation characteristic is reflected in the continuous decrease of liquid and solid lines in the phase diagram of the matrix and the added elements. When the solubility standard and precipitation standard are met, the strengthening sintering effect of additive depends on its influence on the substrate material diffusion rate. The faster the material diffusion rate is, the better the strengthening sintering effect is.

Titanium Alloy Materials Application:
(1) General corrosion-resistant parts are manufactured from treated pure sponge titanium powder through cold-pressure-vacuum sintering. Parts made from titanium powder are already quite mature for the aviation industry. Pure sponge titanium powder or alloy powder is directly rolled into porous titanium or dense titanium plate.

(2) TiAI alloy target materials are produced by means of element powder sintering with titanium powder and aluminum powder as raw materials. In the field of electronics, it is required to use high-vacuum titanium aspirating material, which is usually produced by HDH titanium powder with a large surface area.

(3) Titanium alloy powders are synthesized by cold isostatic pressing and sintering in vacuum sintering furnace, and then by forging or rolling to obtain a variety of profile, this type of titanium alloy profile has a wide range of applications.

(4) HIP prealloy powder was directly formed to produce high-strength titanium alloy products.

(5) Use prealloy powder to directly HIP forming as parts, used for the parts of mid-temperature aero-engine or HIP billet reheating and forming materials, in order to manufacture the load-bearing components for aircraft.

(6) The engine connecting rod made by element mixing and hot isostatic pressure after vacuum sintering is widely used in automobile engines, and the powder metallurgy inlet and exhaust valve is also widely used in automobile industry.

Titanium is widely used in aircraft, rockets, missiles, satellites, spacecraft, ships, military, medical and petrochemical fields. Recent research has found that the human body contains certain titanium elements, titanium elements will stimulate phagocytes, can enhance the immune function, so many laboratories are working on the development and application of biological titanium.

Titanium alloy was widely used in the aerospace field in the early days, mainly used in the manufacture of aircraft engines or pneumatic components. In recent years, the new development of titanium alloy mainly focuses on the following five aspects: medical titanium alloy, flame retardant titanium alloy, high strength and high toughness beta, titanium aluminum compound, high temperature titanium alloy, nickel titanium alloy.