Macrosegregation and the underlying mechanism in Ti-6.5Al-1.0Cr-0.5Fe-6.0Mo-3.0Sn-4.0Zr alloy

A novel method for the analysis of composition distribution of titanium alloys over a large area (64 mm × 72 mm) was investigated by exploring the original position statistic distribution based on spark spectrum (OPA-SS) in Ti-6.5Al-1.0Cr-0.5Fe-6.0Mo-3.0-Sn-4.0Zr titanium alloy. The results showed that OPA-SS could characterize the distribution of elements in different positions on the titanium alloy. The macrosegregation of Sn was the most pronounced, with a statistic segregation degree higher than 18%; the macrosegregation of Mo followed with a statistic segregation degree of 10%; the macrosegregation of Al and Fe was relatively milder, lower than 8%. The main reason for the macrosegregation state of the as-cast Ti-6.5Al-1.0Cr-0.5Fe-6.0Mo-3.0Sn-4.0Zr alloy can be the solute redistribution during liquid solidification and the diffusion rate of each element in the solid phase.