An in-situ neutron diffraction investigation of martensitic transformation in a metastable β Ti-10V-2Fe-3Al alloy during uniaxial tension

The deformation behaviour of a metastable β Ti-10V-2Fe-3Al (wt%) alloy containing ~10 vol% α phase was investigated via single-peak fitting and Rietveld refinement of in-situ neutron diffraction data collected during uniaxial tension. The formation of the 021 fibre is related to martensite variant selection during β → α″ transformation under applied load. The β lattice parameter increases by ~0.08% during tension whereas α″ accommodates deformation through a decrease and increase in a and b lattice parameters, respectively. The origin of the variation in α″ martensite lattice parameters with strain for different Ti alloys is linked to their different rhombicity values. α″