THE GROWTH OF DENDRITES IN SUPERALLOY

The influence of solidification parameters on primary and secondary de ndrite arm spacings of the nickel-base superalloy with composition 6Co -5,04Cr-4,72Al-1,05Ti-1,05Nb-0,96Mo-0,16C-0,02V (wt.%) was studied. Th e samples were prepared by unidirectional solidification with constant thermal gradient 150 K/cm in the melt at L/S interface in the interva l of growth rate from 13,9 to 41,7 mum.s-1. We have found out the aver age primary and secondary dendrite arm spacings are function of the gr owth rate. The primary dendrite arm spacing depends on growth rate and thermal gradient in the melt; at L/S interface according to the relat ion lambda1 = 127, 62 + 38, 09 G(L)-0,5R-0,25. The dependence between secondary dendrite arm spacing and growth rate and G(L) is given by th e relation lambda2 = -3,49 + 41,64 G(L)-0.5 R-0,5.