Processing And Properties Of The High-velocity Compaction Preparation Of Titanium-based Materials

As a new high-density powder metallurgy forming technology, high-velocity compaction (HVC), has the advantage of low cost, high green density and evenly distributed, low springback and high precision, etc. At present, the research of HVC technology at home and abroad are mainly concentrated in some easy forming powder, such as Fe-based and Cu-based powder, while rarely in the powder with a high hardening rate, which are difficulty in forming. Therefore, this paper carried out the HVC forming study of the titanium-based material powder. To expect breakthrough the difficult densification and high cost limitations of the titanium-based materials manufactured by powder metallurgy. The titanium powder, titanium alloy powder, titanium-based mixed elemental powder and composite powder were formed by HVC, the law and forming characteristics of HVC were studied. And the effects of powder property, pressing process, lubrication conditions and sintering temperature on green body and sintered body were also studied.The results of titanium powder show that:An appropriate amount of powder lubricant can effectively reduce the ejection force and improve the maximum impact force. Therefore we can obtain a higher green density at a higher impact energy per mass. For the powder of different particle size, the green density are depends on the powder particle size and bulk density, while the sintered density increases with the decrease of the particle size. At the maximum impact energy, the green densities of-100to-400mesh titanium powder are larger than90%, and the sintered densities are larger than98%.The results of titanium alloy powder and titanium-based mixed elemental powder show that:High-velocity compaction of the different particle size of Ti-6A1-4V alloy powder, with the powder particle size refinement, the green density decreases,while the sintered density increases, and the green density is larger than85%. Compared with-100and-200mesh powder, the green density of-300mesh powder is the lowest,85.1%; while the sintered density is the highest,98.2%; the Vickers hardness and bending strength of the sintered sample are the highest,354HV2.0and1265MPa, respectively. The mixed powder Ti-4.5Al-6.8Mo-1.5Fe were pressed by high velocity compaction technology and then sintered3h in vacuum at the temperature of1050,1150and1350℃, respectively. The overall performance of1150℃sintered sample is the best, the density is99.96%, the Vickers hardness is374HV2.0, and the bending strength is2190Mpa.The results of the TiB/Ti-4.5Al-6.8Mo-1.5Fe titanium matrix composite powder show that:The10vol%TiB/Ti-4.5Al-6.8Mo-1.5Fe sample, sintered at1250℃,has the maximum aspect ratio of TiB whisker, and the sample having the best tensile strength, which is1179Mpa, higher than that of the matrix alloy. This is mainly due to having a good density of the sample, the larger aspect ratio of TiB whisker, and the more uniform organization.Overall, HVC technology can high density form various types of titanium-based powder, and develop a new way to manufacture high performance titanium-based material with short process and low-cost, by HVC and vacuum sintering.