A study of fracture behaviour of gamma lamella using the notched TiAl micro-cantilever

Microcantilevers were machined from a single gamma(TiAl)-alpha(2)(Ti3Al) lamellae colony of a polycrystalline commercial Ti-45Al-2Mn-2Nb sample using the focussed ion beam. The long axis of the microcantilevers is perpendicular to the lamellar interface with the notch prepared in the same gamma lamella. Bending test results demonstrated good repeatability and the fracture stress intensity factor of individual gamma lamella was measured to be 3.1 +/- 0.2 MPa m(1/2). twinning ahead of the notch (crack) tip plays a key role in the crack initiation. TEM analysis shows that the interaction of twinning with the lamellar interface leads to interfacial cracking and contributes to the work-hardening observed.