Microstructure of fine-grained β-type titanium alloy produced by mechanical alloying and consolidation process

The mechanical alloying (MA) treatment was applied to the mixed powder of titanium and iron with average composition of Ti-15 mass%Fe. Heptane was also used for the MA treatment as a source of carbon. The MA treatment resulted in the production of alloyed powder in which all constituents were fully dissolved in the solid solution. By the consolidation of the MA-treated powder (hot rolling at 1073 K), a bulk material of β-type titanium alloy with fine-grained structure was successfully obtained. As a result of TEM observation, it was found that the TiC particles with a size of 200 nm were dispersed within the β-Ti matrix structure. The mean grain size of β-Ti was measured at around 1-2 μm. Although the fine-grained β-type titanium alloy produced by the MA treatment and consolidation process has very high hardness, it was also found that a significant amount of metastable coarse metallic compounds, Ti2Fe, existed in the material, leading to the deterioration of ductility of the consolidated material.