The effects of carbon addition (0.01wt%-0.43wt%) on a Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-1Nd (wt%) alloy with a bimodal microstructure were investigated. Electron probe microanalysis was carried out to examine the partitioning behavior of carbon and the relation of carbon content to the distributions of Al and Mo in the primary α phase (αp) and β transformed structure (β). It was found that interstitial carbon is enriched in the αp phase and its content slightly reduces with the increase of the volume fraction of αp.The measurements of carbon content in the present alloy with an αp of 15vo1% showed that the carbon content in the αp phase increases with the increment of carbon addition until a maximum but keeps almost constant in the β phase. The addition of carbon reduces the solubility of Al and Mo in the αp phase and leads to the increment of Mo partitioning to the β phase. When the carbon content is over 0.17wt% (0.67at%), carbide precipitation occurs in the matrix and its volume fraction is related to the volume fraction of αp which can be explained in term of the difference of carbon solubility in the αp and β phases.
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