Ductile deformation in alumina ceramics under quasi-static to dynamic contact impact
Robert Crookes
Benjamin Maerz
Houzheng Wu
2134/10316378.v1
https://repository.lboro.ac.uk/articles/journal_contribution/Ductile_deformation_in_alumina_ceramics_under_quasi-static_to_dynamic_contact_impact/10316378
Florescence
spectroscopy and TEM has been used to study the ductile deformation of alumina
ceramics underneath an impact contact. The contact was generated by a spherical
tungsten carbide indenter under quasi-static, drop weight and ballistic loading
conditions. In all circumstances, a ductile deformation region containing
dislocations developed below each contact impression. The dislocation density
distribution complies to the shear stress distribution predicted by the Hertzian
contact model. Ballistic loading resulted in secondary material flow, giving a
maximum dislocation density 5-10 times higher than that dictated by the Hertzian
contact model. Quantification of dislocation density distribution allowed a
critical shear stress for dislocation generation to be estimated. In this
alumina ceramic, the critical shear stress is estimated as 2.55 ± 0.10 GPa. Cold work hardening and comminution
under dynamic loading are discussed as possible mechanisms for the enhanced
dislocation activity under dynamic impact.
2019-11-18 10:57:05
Materials
Materials Engineering
Manufacturing Engineering
Mechanical Engineering