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

ABSTRACT

Microcantilevers were machined from a single γ(TiAl)-α₂(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 γ lamella. Bending test results demonstrated good repeatability and the fracture stress intensity factor of individual γ lamella was measured to be 3.1 ± 0.2 MPa m^1/2. $\left(\overline{1}\overline{1}1\right)\left[\overline{1}\overline{1}\overline{2}\right]$ 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.

KEYWORDS:

• Fracture
• FIB
• Electron microscopy
• γ-TiAl
• Microcantilever

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Sanjooram Paddea http://orcid.org/0000-0001-5981-3987

Additional information

Funding

Dr Chu would like to acknowledge the financial support from the Program for Guangdong Introducing Innovative and Enterpreneurial Teams (No. 2016ZT06G025) and Guangdong Natural Science Foundation (No. 2017B030306014), People’s Republic of China.