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.