Effect of Cr on microstructural evolution of aluminized fourth generation Ni-base single crystal superalloys

► Effects of Cr on microstructure in aluminized fourth generation Ni-base superalloys. ► Higher Cr encourages secondary reaction zone nucleation after aluminizing. ► Higher Cr precipitated more topologically close-packed phases in substrate. ► Cr accelerates secondary reaction zone nucleation, but not for their growth.