Non-equilibrium arc-melted binary Ti-Fe bulk alloys with ultra-high strength and enhanced ductility

摘要

In the present work we report on the formation of the high-strength and ductile hypo-, hyper- and eutectic Ti-Fe arc-melted alloy ingots with the dimensions of about 25-30 mm in diameter and 10-15 mm in height. The structure of the samples studied by X-ray diffractometry and scanning electron microscopy is found to consist of cubic Pm3m TiFe and BCC Im3m β-Ti supersaturated solid solution phase. The arc-melted Ti_(65)Fe_(35) alloy has a dispersed hypereutectic structure consisting of the primary TiFe phase and submicron-size eutectic structure. The arc-melted Ti_(65)Fe_(35) alloy ingot sample exhibits excellent mechanical properties: a Young's modulus of 149 GPa, a high mechanical fracture strength of 2.2 GPa, a 0.2 % yield strength of 1.8 GPa and 6.7% ductility. The hard round-shaped intermetallic TiFe phase and the supersaturated β-Ti solid solution result in a high strength of the Ti_(65)Fe_(35) alloy which in addition has much higher ductility compared to that of the nanostructured or glassy alloys. The ductile β-Ti solid solution phase enables plastic deformation of the sample. The reasons for the high ductility of the hypereutectic alloy are discussed.