In 1948, the U.S. DuPont used the magnesium reduction method to mass produce titanium sponge – this marks the beginning of the industrialized production of titanium sponge that is Titanium and titanium alloy are also widely used in various fields due to their high specific strength, good corrosion resistance, and heat resistance. Titanium alloy has been used in the aviation industry for more than half a century; in recent years, in the field of 3C, Huawei, Apple, Xiaomi, Glory, and other cell phones have been imported into the titanium shell, more and more 3C manufacturers are expected to use titanium alloy. So why is titanium alloy so widely favored?
Properties of Titanium
High specific strength: 1.3 times that of aluminum alloy, 1.6 times that of magnesium alloy, 3.5 times that of stainless steel, the champion among metal materials.
High thermal strength: the use temperature is several hundred degrees higher than that of aluminum alloy, and it can work for a long time under the temperature of 450-500℃.
Good corrosion resistance: acid, alkali, and atmospheric corrosion resistance, extreme resistance to pitting, and stress corrosion.
Good low-temperature performance: titanium alloy Ti-5Al-2.5Sn with deficient interstitial elements can maintain a certain degree of plasticity at -253℃.
High chemical activity: high chemical activity at high temperatures, efficiently reacting chemically with hydrogen, oxygen, and other gaseous impurities in the air to generate a hardened layer.
Small thermal conductivity: the thermal conductivity is about 1/4 of nickel, 1/5 of iron, and 1/14 of aluminum.
Classification and use of titanium alloys
Titanium alloys can be categorized into heat-resistant alloys, high-strength alloys, corrosion-resistant alloys (titanium-molybdenum, titanium-palladium alloys, etc.), low-temperature alloys, and alloys with special functions (titanium-iron hydrogen storage materials, titanium-nickel memory alloys). Although Titanium and its alloys have been used briefly, they have been awarded several honorable titles for their outstanding performance. The first title is “space metal,” which is lightweight, high strength, and high temperature resistant, especially suitable for manufacturing airplanes and various spacecraft. At present, about 75% of the titanium and titanium alloys produced in the world are used in the aerospace industry. Many parts initially made of aluminum alloys have been replaced by titanium alloys.
Aerospace applications of titanium alloys
Titanium alloys are mainly used to manufacture aircraft and engine materials, such as forging titanium fans, pressurizer discs and blades, engine cowlings, exhaust devices, and other parts, as well as aircraft beams, compartment frames, and other structural frame parts. Spacecraft mainly use high-strength, corrosion-resistant, and low-temperature-resistant titanium alloys to manufacture various pressure vessels, fuel storage tanks, fasteners, instrument straps, frames, and rocket shells. Artificial Earth satellites, lunar modules, manned spacecraft, and space shuttles also use titanium alloy plate weldments.
In 1950, the United States first used the F-84 fighter bomber as the rear fuselage heat shield, windshield tail cowl, and other non-load-bearing components. The 1960s began using titanium alloy parts from the rear fuselage to the middle of the fuselage, partially instead of structural steel manufacturing spacer frames, beams, flaps, slides, and other important load-bearing components. In the 1970s, civil aircraft began to use many titanium alloys, such as the Boeing 747 airliner Titanium, which amounted to more than 3640 kilograms and accounted for 28% of the weight—with the development of processing technology, rockets, satellites, and spacecraft also used a lot of titanium alloy. The more advanced the airplane, the more Titanium is used. U.S. F-14A fighter using titanium alloy, accounting for about 25% of the weight of the machine; F-15A fighter for 25.8%; U.S. fourth-generation fighters with titanium amount of 41% of its F119 engine with titanium amount of 39%, is the current amount of Titanium with the highest amount of airplanes.
Reasons for the extensive use of titanium alloys in aerospace
Why does the material for air transport aircraft have to be Titanium?
Modern airplanes are sailing at a top speed of more than 2.7 times the speed of sound. Flying at supersonic speeds causes a lot of heat to be generated by the friction between the airplane and the air. When the flight speed reaches 2.2 times the speed of sound, the aluminum alloy can not withstand and must use high-temperature resistant titanium alloy. When the aero-engine thrust-to-weight ratio from 4 to 6 increased to 8 to 10, the pressurized gas outlet temperature correspondingly from 200 to 300 ℃ risen to 500 to 600 ℃, the original low-pressure pressurized gas discs and blades made of aluminum must be changed to titanium alloy.
In recent years, scientists have been working on the performance of titanium alloy research and are constantly making new progress. The original Titanium, aluminum, and vanadium were composed of titanium alloy, with a maximum operating temperature of 550 ℃ ~ 600 ℃. In the newly developed titanium aluminum (TiAl) alloy, the maximum operating temperature has increased to 1040 ℃. Instead of stainless steel, titanium alloy can be used to manufacture high-pressure compressor disks and blades, which can reduce the structure’s weight. Aircraft can save 4% of fuel for every 10% weight reduction. For rockets, for every 1kg of weight reduction, the range can be increased by 15km.
3C Applications of Titanium Alloys
Currently, the consumer electronics industry represented by cell phones is very “revolutionary”; the head of the manufacturers hopes to borrow titanium alloy to improve the product’s premium ability.
Huawei, Apple, millet, Glory, and other cell phones have imported the material. Apple, from the Ultra series of watches, began to standardize titanium alloy cases; its latest release, the iPhone15, which is a Pro version of the new titanium metal body, became Apple’s first cell phone using aviation-grade Titanium; Huawei released in 2022 folding screen phone, Mate Xs2 structural parts in titanium alloy materials, and Watch4 Pro in the use of titanium alloy bezel; Glory! Released on October 12, the light and thin, large internal folding flagship phone, Glory Magic Vs2, uses Lupin titanium hinges and other innovative materials. The new Millet 14 machine has the highest pricing, the 14Pro titanium version.
It is reported that Samsung will use a titanium alloy center frame on the Galaxy S24 Ultra; the center frame part is similar to the original color titanium color scheme of the iPhone 15 Pro.
Overall, titanium alloy, with its high specific strength and lightweight advantages, is highly promoted as an essential reason. This can make consumer electronics products lighter, and the consumer experience will be more comfortable.
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