The difference between titanium alloy and magnesium alloy

magnesium alloy
Magnesium alloy is an alloy based on magnesium with other elements added. The main alloying elements are aluminum, manganese, zinc, cerium, thorium, and small amounts of zirconium and cadmium. Currently the most widely used is magnesium-aluminum alloy, followed by magnesium-manganese alloy and magnesium-zinc alloy. Magnesium alloys can be widely used in automobiles, electronics, textiles, construction and military fields due to their excellent casting, extrusion, cutting and bending properties.

The melting point of magnesium alloy is 650°C and has good die-casting properties. The tensile strength of magnesium alloy castings can generally reach 250MPa, and the highest can reach more than 600MPa.

Magnesium alloy has low density (about 1.8g/cm3) and high strength. Magnesium alloy is the lightest metal structural material, with a specific gravity of only 1.8, which is 2/3 that of aluminum and 1/4 that of iron. Its specific strength is as high as 133, which makes magnesium alloy a high-strength material. Magnesium alloy has a large elastic modulus and good shock absorption. Within the elastic range, magnesium alloys absorb half the energy than aluminum alloy parts when subjected to impact loads, so magnesium alloys have good impact resistance and noise reduction properties.

The die-casting performance of magnesium alloy is very good. The minimum wall thickness of die castings can reach 0.5mm, which is suitable for manufacturing various automotive die castings. Magnesium alloy parts have high stability, die castings have high castability and dimensional accuracy, and can be processed with high precision.

Compared with alloys, magnesium alloys have absolute advantages in heat dissipation. For radiators made of magnesium alloy and aluminum alloy of the same volume and shape, the heat (temperature) generated by a certain heat source is more easily transferred by the magnesium alloy through the radiator root than the aluminum alloy. The faster you get to the top, the easier it is for the top to reach high temperatures.

However, the linear expansion coefficient of magnesium alloy is very large, reaching 25-26μm/m℃, while that of aluminum alloy is 23μm/m℃, brass is about 20μm/m℃, structural steel is 12μm/m℃, and cast iron is about 10μm/m℃. m°C. Rocks (granite, marble, etc.) are only 5 to 9 μm/m°C, and glass is 5 to 11 μm/m°C. When applying it to heat sources, the effect of temperature on the size of the structure must be considered.

Application examples of magnesium alloy: Generally, mid-to-high-end and professional digital SLR cameras use magnesium alloy as the frame to make it strong, durable and good in hand; casings of mobile phones and laptops; heat dissipation parts of computer and projector casings that generate high temperatures inside use magnesium Alloy; automotive steering wheels, steering brackets, brake brackets, seat frames, rearview mirror brackets, distributor brackets and other structural parts that require lightweight and high strength.

According to the forming method, it is divided into two categories: deformed magnesium alloy and cast magnesium alloy.

Magnesium alloy grades are expressed in the form of English letters, numbers and English letters. The first English letter is the code name of its most important alloying component element, and the following numbers represent the average value of the upper and lower limits of its most important alloying component element. The last English letter is the identification code, which is used to identify different alloys with different specific constituent elements or slightly different element content.
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Titanium alloy

Titanium alloy refers to an alloy metal made of titanium and other metals. They have high strength, good corrosion resistance and high heat resistance. Titanium alloys are widely used in the production of aircraft engine compressor parts, frames, skins, fasteners and landing gears. Titanium alloys are also used in structural parts of rockets, missiles and high-speed aircraft.

The melting point of titanium is 1668°C. It has a close-packed hexagonal lattice structure below 882°C and is called alpha titanium; it has a body-centered cubic lattice structure above 882°C and is called beta titanium. By utilizing the different characteristics of the above two structures of titanium and adding appropriate alloying elements, titanium alloys with different structures can be obtained. At room temperature, titanium alloys have three matrix structures, and titanium alloys are divided into the following three categories: α alloys, (αβ) alloys and β alloys. In our country, they are represented by TA, TC, and TB respectively.

The density of titanium alloys is generally around 4.51g/cm3, which is only 60% of steel. Some high-strength titanium alloys exceed the strength of many structural steel alloys. Therefore, the specific strength (strength/density) of titanium alloys is much greater than that of other metal structural materials. , can produce parts with high unit strength, good rigidity and light weight.

Titanium is non-toxic, lightweight, strong and has excellent biocompatibility. It is an ideal medical metal material and can be used as an implant in the human body. In the United States, 5 beta titanium alloys have been recommended for use in the medical field, namely TMZFTM (TI-12Mo-^Zr-2Fe), Ti-13Nb-13Zr, Timetal 21SRx (TI-15Mo-2.5Nb-0.2Si)), Tiadyne 1610 (Ti-16Nb-9.5Hf) and Ti-15Mo are suitable for implantation into the human body, such as artificial bone, vascular stents, etc.

TiNi alloy has good biocompatibility, and there are many medical examples that utilize its shape memory effect and superelasticity. Such as thrombus filters, spinal orthopedic rods, dental orthopedic wires, vascular stents, bone plates, intramedullary needles, artificial joints, contraceptive devices, heart repair parts, micropumps for artificial kidneys, etc.

Titanium alloy products can be obtained by die casting and machining. The melting temperature of titanium alloy is very high, and the requirements for mold steel are also very high. There are many processing methods for titanium alloys, including: turning, milling, boring, drilling, grinding, tapping, sawing, EDM, etc.

Titanium alloys also have poor machinability. The cutting forces when cutting titanium alloys are only slightly higher than steel of the same hardness. However, the thermal conductivity of most titanium alloys is very low, only 1/7 of steel and 1/16 of aluminum, so the heat generated by cutting will not dissipate quickly. Accumulate in the cutting area, causing rapid wear, collapse, and built-up edge on the tool edge.