材料期刊网

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 alpha phase (alpha(p)) and beta transformed structure (beta). It was found that interstitial carbon is enriched in the alpha(p) phase and its content slightly reduces with the increase of the volume fraction of alpha(p). The measurements of carbon content in the present alloy with an alpha(p) of 15vo1% showed that the carbon content in the alpha(p) phase increases with the increment of carbon addition until a maximum but keeps almost constant in the beta phase. The addition of carbon reduces the solubility of Al and Mo in the alpha(p) phase and leads to the increment of Mo partitioning to the beta 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 alpha(p) which can be explained in term of the difference of carbon solubility in the alpha(p) and beta phases.