The application of powder metallurgy light metal alloy on automobiles

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Due to the implementation of automobile lightweight, it has provided broad application prospect for aluminum, magnesium, titanium and other light metal materials. Although aluminum alloy powder can be used in a lot of parts of automobiles, Al-Si alloy may firstly have large application on oil pump gear due to its high specific strength, high specific stiffness, low thermal expansion coefficient and good wear resistance. In view of industrialization, it is more important to carry out the optimization study on the preparation process of powder metallurgy aluminum alloy.

The other research spot of aluminum alloy is composite, including the traditional AI/SiC, AI/C, AI/BN, AI/Ti(C,N) as well as the emerging carbon nanotubes reinforced aluminum alloy. High strength aluminum powder is closely related with rapid solidification. By designing composition and adding intermetallic compound in the pure aluminum substrate, aluminum alloy that has high strength, high tenacity and high thermal stability can be generated. The room temperature strength of this kind of material will be more than 600Mpa and the ductility will exceed 10 percents. Besides, it will still have good thermal stability at 400 degrees Celsius and the fatigue limit is 2 times of aluminum casting alloy.

Magnesium alloy has lower density than aluminum alloy and may have better application prospect, but it is still under research status. Rapid solidification is also an important means of producing high performance magnesium alloy powder. Currently, there is almost no safety problem that exists in this technology. Besides, the performance of the materials that produced by this technology is far better than the casting alloys.

High cost can be regarded as a main problem that exists in the application of titanium alloy on automobiles, while the main obstacle of titanium alloy powder lies in the high performance low cost titanium powder. (GB) QinetiQ Ltd has developed a kind of electro-deoxidization technology (EDO) that can be used in the batch production of titanium powder. This technology is entirely different with the traditional hydrogenation dehydrogenation process that uses titanium sponge as the raw material, which is a kind of method that is similar with molten salt electrolysis, in which TiO2 is used as the cathode and graphite is used as the anode. In the electrolysis process, the oxygen in TiO2 will migrate to anode and will generate CO after consuming the carbon in the anode, thus titanium powder can be generated in the cathode. The oxygen content of titanium powder is in the range of 0.035 percent-0.4 percent. This technology can be used in producing various titanium alloy powders. Due to the sensibility to atmosphere and impurities, the sintering of titanium alloy powder can also be regarded as a technical difficulty, which often needs hot isostatic pressure or subsequent hot working. By adding eutectic and rare earth elements, the sintered density of titanium alloy powder can be obviously improved as well as its mechanical property will also reach the level of forging titanium alloy. This series of work will greatly promote the application of titanium alloy on the engine key parts of automobiles.