The effect of a small addition of nickel on the sintering, sintered microstructure, and mechanical properties of Ti-45Al-5Nb-0.2C-0.2B alloy

Abstract

Titanium aluminide based pre-alloyed powder is difficult to consolidate by pressureless sintering. The effect of a small addition of nickel (Ni) on the sintering, sintered microstructure, and mechanical properties of a Ti-45Al-5Nb-0.2C-0.2B alloy, compacted from pre-alloyed powder, has been investigated. The relative density of the alloy, sintered at 1375 °C for 60 min, increased progressively from 74% to >99% with increasing Ni content from 0% to 1.25 at.%. The addition of Ni leads to the formation of an intermediate hexagonal-structured Al3NiTi2 phase (known as the τ3 phase) during heating prior to reaching 1150 °C. The presence of the τ3 phase enables the formation of a Ni-containing sint..