The microstructure optimizing of the Nb–14Si–22Ti–4Cr–2Al–2Hf alloy processed by directional solidification

Abstract In this work, the microstructure evolution of an Nb–14Si–22Ti–4Cr–2Al–2Hf alloy processed by liquid-metal-cooled directional solidification (LMC) and heat treatment (HT) was investigated. The microstructure in the quasi-steady-state growth region of the LMC ingot consisted of primary (Nb,Ti) SS dendrites and eutectic (Nb,Ti) SS /(Nb,Ti) 5 Si 3 . The unstable (Nb,Ti) 3 Si phase was eliminated and the eutectic with coupled (Nb,Ti) SS and (Nb,Ti) 5 Si 3 occurred. After heat treatment of selection, the fiber reinforcing mash structure was maintained: the (Nb,Ti) SS phase connected to be a continuous matrix and the fine discontinuous fibrous (Nb,Ti) 5 Si 3 was distributed uniformly and parallel to the growth direction on longitudinal section.