“…The addition of these heavy refractory elements has conferred considerable solid solution strengthening with simultaneous increases in high temperature creep resistance. For this reason, the total amount of refractory alloying addition has been gradually increased in the advanced Ni-base superalloys [1,2]. However, the refractory elements segregate severely during solidification [3,4], which often lead to a number of problems such as (i) interdendritic porosity [5], (ii) misoriented grains [6], (iii) freckle formation [6,7], (iv) localized phase instability [8,9], and (v) formation of topologically close-packed (TCP) phases [9,10].…”