Growth of Crystals and Formation of C40/C11_b Lamellar Structure in (Mo_0.85Nb_0.15)Si₂

In this paper, high-quality single crystals of (Mo(0 85)Nb(0 15))Si(2) around 8 mm in diameter and 90 mm in length, have been grown by optical heating floating zone method. Effects of chemical composition and growth rate on forming C40 structured single crystal were studied. Aligned C40/C11(b)) lamellar structured can be formed in the as-grown crystals after post annealing at temperatures between 1473 and 1873 K Chemical composition as well as annealing temperature are found to be two important factors to form C11(b) lamellae in the C40 matrix Fully C40/C11(b) lamellar structure was formed after annealing at 1873 K in the present work The aligned C40 and C11(b) lamellae follow a crystallographic orientation relationship of (0001)C40//( 110)C11(b). Dislocations were observed in some coarse C11(b) lamellae but never in C40 lamellae of the duplex structure This is probably due to accumulation of misfit strain during formation of C40/C11(b) lamellae.