Work hardening and recovery in fully lamellar TiAl: relative activity of deformation systems

ABSTRACT

The relative activity of deformation systems during work hardening and thermal recovery has been investigated in fully lamellar TiAl. This has been done by a combination of a series of deformation/static recovery experiments and numerical simulations based on a defect density-based crystal plasticity model. Firstly, active deformation systems in differently oriented polysynthetically twinned crystals/single lamellar colonies have been studied. Subsequently, numerical experiments on a polycolony microstructure have been used to investigate the inhomogeneous microplasticity (i.e. the typical microyield) in fully lamellar TiAl. From this, it has been possible to analyse how changes in the lamella thickness, domain size and colony size influence the onset of macroscopic yield. Based on static recovery experiments with differently oriented polysynthetically twinned crystals, numerical studies have revealed trends in the recovery of work hardening in both polysynthetically twinned crystals and polycolony microstructures.

KEYWORDS:

• TiAl
• titanium aluminides
• crystal plasticity
• work hardening
• recovery

Acknowledgments

Support by the Assessment, Computing and Engineering Centre (ACE) of the Helmholtz-Zentrum Geesthacht is gratefully acknowledged. We further thank Andreas Stark (Institute of Materials Research, Materials Physics, Helmholtz-Zentrum Geesthacht, Germany) for providing the polysynthetically twinned crystal material and Marcus W. Rackel (Institute of Materials Research, Materials Physics, Helmholtz-Zentrum Geesthacht, Germany) for providing the micrograph in Figure 1.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jan Eike Schnabel http://orcid.org/0000-0002-9211-4130