The creep behavior of powder-metallurgy processed Ti-6Al-4V-1B(wt.%)

The elevated-temperature (400-455 °C) tensile-creep deformation behavior of a powder-metallurgy processed Ti-6Al-4V-1B(wt.%) alloy was evaluated for applied stresses between 400 MPa and 450 MPa. The extruded alloy exhibited aligned TiB whiskers along with a lenticular α+β phase morphology. In situ tensile-creep observations indicated that the TiB whisker cracking occurred prior to crack formation in the α and β phases. The extent of surface cracking within the secondary creep stage was significant. Post-mortem analysis revealed that TiB cracking was also observed within the bulk of the sample though the extent of cracking within the bulk was not as severe as at the surface. Overall, the secondary creep rates were similar to that for a Ti-6Al-4V-1B(wt.%) cast alloy and significantly lower than those for Ti-6Al-4V(wt.%). Thus, 1 wt.%B improved the creep resistance of Ti-6Al-4V(wt.%).