Tailoring the microstructure of molybdenum disilicide matrix composites with Nb additions

The effect of Nb addition on the microstructure of MoSi2 alloy was studied. Two kind of composition designations were adopted to get different microstructures. In the first group, the compositions are designed as Mo1/3(1−x)Si2/3(1−x)–xNb (x=0.05, 0.1 and 0.4375). In this group, a composite containing MoSi2 and Nb5Si3 as well as Nb5Si3C is formed. The volume fraction of Nb5Si3 and Nb5Si3C phases increase with Nb addition and become the predominant matrix phase when Nb addition is 43.75%. In the second group, the compositions are designed as (Mo1−x, Nbx)Si2. A composite containing MoSi2 and NbSi2 as well as a small amount of Nb5Si3 is formed.