Study of Chemical Inhomogeneity in Beta-Solidifying TiAl Alloys of Various Composition

The results of original research into the structure and statistical distribution of elements alloyed into ingots from a new Russian intermetallic TiAl alloy having two variable compositions (Ti-44.5Al-2V-1Nb-1.5Zr/2.5Cr-0.1Gd, at.%) are presented. The experimental ingots having a nominal weight of 3-30 kg were obtained according to two technological schemes: 1 - triple vacuum arc remelting (VAR + VAR + VAR) with a consumable compacted electrode; 2 - VAR -> VAR -> single vacuum induction melting (VAR + VAR + VIM) in a cold crucible furnace. The statistical processing of the chemical analysis results was carried out using Shewhart charts. The results indicate a minimum degree of volumetric macrosegregation in the ingots and the almost complete absence of segregation inhomogeneity in Zr- and Cr-containing compositions: the maximum range of Al content over the cross section of triple-remelted ingots was no more than 0.84 at.% (0.42 wt.%), while along the height of the ingots, Al content was no more than 1.87 at.% (0.55 wt.%).