  Multiphase titanium alloys are critical materials in high value engineering
components, for instance in aero engines. Microstructural complexity is
exploited through interface engineering during mechanical processing to realise
significant improvements in fatigue and fracture resistance and strength. In
this work, we explore the role of select interfaces using in-situ
micromechanical testing with concurrent observations from high angular
resolution electron backscatter diffraction (HR-EBSD). Our results are
supported with post mortem transmission electron microscopy (TEM). Using
micro-pillar compression, we performed in-depth analysis of the role of select
{\beta}-titanium (body centred cubic) ligaments which separate neighbouring
{\alpha}-titanium (hexagonal close packed) regions and inhibit the dislocation
motion and impact strength during mechanical deformation. These results shed
light on the strengthening mechanisms and those that can lead to strain
localisation during fatigue and failure.
