Fabricating Ti_2AlNb sheet with high tensile strength and good ductility by hot packed rolling the spark plasma sintered pre-alloyed powder

摘要

In this work, a novel "spark plasma sintering (SPS) of pre-alloyed powder followed by a hot packed rolling" method is proposed to fabricate the Ti_2AlNb sheet. Ti2AlNb sheets with high tensile strength and good ductility are obtained without any post heat treatment. Ti_2AlNb compact is first prepared by SPS of the pre-alloyed powders. The compact sintered at 1060 °C consists of only B2 phases with an average grain size of 25.88 μm. No α2 phase forms after rolled at 1030 °C and the B2 grain size increases by increasing the rolling passes because of the fast grain growth of B_2 grains. Numerous ultrafine O phases precipitated inside the B_2 matrix after cooled in air, and they contribute to the excellent strength and ductility of the sheets. The mechanical property tests showed that the sheets rolled by 2 passes (thickness reduction: 42% + 42%) and 4 passes (30% + 21% + 21% + 21%) had the maximum tensile strength of 1239.03 MPa and the maximum elongation of 9.49%, respectively. All the rolled sheets presented ductile fracture mode with numerous dimples on the fracture surface.