The development trend of titanium and titanium alloy powder metallurgy technology

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Titanium and titanium alloy parts that produced by powder metallurgy technology will have no composition segregation as well as have even structure and stable performance. The application of titanium on the automobile can be regarded as a very attractive market. By developing new low cost raw material production method and combining it with the advanced powder metallurgy near forming technology, titanium is expected to enter into automobile industry. At present, high cost can be regarded as the main obstacle that exists in the wide application of titanium and titanium alloy. Therefore, powder metallurgy technology can effectively reduce the cost. In order to meet the requirements of further reducing the production cost of titanium and titanium alloy, new titanium powder forming technology is springing up continuously.

titanium metal powder metallurgy

Titanium warm compacting process

This technology is based on powder metallurgy warm compacting process and combines the advantages of metal injection molding process. By adding a certain amount of micro powder as well as increasing the lubricant or adhesives content, the mobility, filling ability and crystallized ability of mixed powder can be improved, thus the powders can be used in making the parts that have complex shapes. Therefore, this technology will have very wide development prospect.

Researches about the application of warm compacting process on the preparation of powder metallurgy titanium alloy have been carried out. In the experiment, pure titanium that is made by hydrogenation dehydrogenation method is used as the raw material and will be suppressed under 500MPa. Afterwards, the compact will have vacuum sintering at 1280 degrees Celsius. Research shows that the tensile strength will reach to the maximum value of 1051MPa when the temperature of powder and mold is at 155 degrees Celsius. This is because under the effect of temperature, the plasticity of titanium metal powder will be improved, which will have coordination deformation effect on the particle rearrangement in the pressing process and will increase the pressed density. On this basis, they carried out the research on the die wall lubricated warm compaction of mixed powder that has the nominal composition of Ti-6.8Mo-4.5Al-1.5Fe-1.5Nb by using zinc stearate as the die wall lubricant under same pressing conditions. After the pressing process, the compact density can reach 86 percents to 90 percents of the theoretical density and has exceeded the performance index of cold isostatic pressing technology.

Titanium injection molding

Pure titanium parts can be produced by the injection forming technology. The experiment uses the hydrogenation dehydrogenation titanium powders that have the average particle size of 23 micrometers that will be sintered at the temperature in the range of 1198-1348K. When the temperature is more than 1298K, the tensile strength will be more than 630MPa; when adding a certain amount of gas atomized powders that have the average particle size of 15 micrometers in the hydrogenation dehydrogenation titanium powders, the sintered compact that has very high sintered density will be formed under low sintering temperature (1248-1298K), besides, the percentage elongation can reach 15percents to 20 percents. Metal injection molding technology can also be used on Ti-6Al-4V alloy powders, by sintering it at 1223K, Ti-6Al-4V alloy that has more than 96 percents of relative density and the tensile strength of 950MPa can be formed. Alloy powder can be produced by self-diffusion high temperature synthesis, which can be used in producing sintering parts that have the relative density of 97 percents and will have very high strength and ductility after mixing with organic adhesives, stirring, injection molding and sintering. By preparing the injection molded pure titanium with the titanium powder that is produced by hydrogenation dehydrogenation method at the vacuum sintering temperature of 1250 degrees Celsius, the sintered density can reach up to 98 percents. When the titanium powder is sintered for 1.5 hours under this temperature, the tensile strength and elongation of the products will respectively reach 349MPa and 6.4 percents.