Characteristics and Properties of Ti-8Mo-6Cr Alloys with Added NbC Powders through the Vacuum Sintering Process at Various Temperatures

抄録

In this study, three different powders are mixed and used to produce Ti-8Mo-6Cr-xNbC alloys of three different proportions: Ti-8Mo-6Cr-1NbC, Ti-8Mo-6Cr-3NbC and Ti-8Mo-6Cr-5NbC. The Ti-8Mo-6Cr-xNbC alloys simultaneously undergo a vacuum sintering process at temperatures of 1250, 1275 and 1300℃, respectively. The experimental results show that the lowest apparent porosity (0.1%) and highest hardness (66.5 HRA) of the Ti-8Mo-6Cr-1NbC alloys are acquired after sintering at 1300℃ for 1 h. However, the transverse rupture strength (TRS) values of the Ti-8Mo-6Cr-1NbC alloys sintered at 1300℃ display an obvious decrease as a result of the grain-coarsening phenomenon. Due to the TiC precipitates, grain refinement and a lower porosity appear in the 1250℃-sintered Ti-8Mo-6Cr-1NbC alloys, with the TRS showing an obvious increase (as compared with Ti-8Mo-6Cr, the TRS value increases from 1333 to 1532 MPa). These alloys also have the lowest corrosion current (I_corr was 1.47 × 10⁻⁵ A·cm⁻²) and highest polarization resistance (R_P was 3.61 × 10³ Ω·cm²) in 1M H₂SO₄ solutions. These results confirm that the Ti-8Mo-6Cr-1NbC alloys sintered at 1250℃ possess the suitable mechanical properties and optimal corrosion resistance.