Transformations of α' martensite in Ti–Fe alloys under high pressure torsion

Abstract Phase transitions in α'-Ti martensite driven by high pressure torsion (HPT) as well as α' → ω transformations in Ti–Fe alloys were observed for the first time. The as cast alloys transformed into α'-Ti martensite after annealing in the β-(Ti,Fe) solid solution region and subsequent quenching. Lattice parameters of α'-Ti martensite decreased with increasing iron content, similar to the lattice parameter of β-Ti. During HPT, α'-Ti martensite transformed partly into ω-Ti. At the same time, the lattice parameters of remaining α'-Ti phase increased towards those for iron-free α-Ti. These processes included an increased mass transfer of iron atoms out of α'-Ti.