Microstructure and mechanical properties of Nb-Si alloy with addition of Mn

The effect of Mn element on the microstructure and mechanical properties of Nb-Si based alloys is studied, and the investigated alloys compositions are Nb-16Si-22Ti-xMn (x = 0, 2, 4, 8 at.%). Solubility of Mn in Nbss phase is higher than that in silicide. This dissolution of Mn in Nbss phase and silicide causes solid solution strengthening. Tiss phase and Mn2Ti phase eutectic structure precipitates between dendrites of 8Mn alloy, which affect room-temperature fracture toughness and compressive strength adversely. After heat treatment, Tiss phase and Mn2Ti eutectic structure almost disappears in Mn-contained alloys (Nb, Ti)(3)Si phase decomposes and transforms to Nbss phase and alpha-(Nb, Ti)(5)Si-3 phase. The fracture toughness of heat treated 8Mn alloy has been improved greatly due to Mn solution strengthening in Nbss phase. (C) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).