M. Dao et al., DEFORMATION AND FRACTURE UNDER COMPRESSIVE LOADING IN LAMELLAR TIAL MICROSTRUCTURES, Philosophical magazine. A. Physics of condensed matter. Structure, defects and mechanical properties, 74(3), 1996, pp. 569-591
A physically based micromechanical model is applied to study finite co
mpressive deformation behaviour and the development of failure modes i
n polycrystalline fully lamellar and nearly lamellar microstructures.
Orientation-dependent yielding of lamellar TiAl single crystals is spe
cifically modelled. Finite-element computations show that deformation
is inherently non-uniform in the lamellar microstructure, in accordanc
e with results presented earlier by Kad, Dao and Asaro. Intergranular
fracture initiation is found to be expected at small aggregate strains
(i.e. strains less than 5%), while fracture initiated by internal buc
kling is found to be increasingly likely to occur at larger aggregate
strains (i.e. strains larger than 5-10%). Internal buckling is found i
n lamellar TiAl crystals whose lamellae are initially nearly parallel
to the compressive loading. A weak basal texture, normal to the compre
ssion axis, is developed at only 20% aggregate strain. Subtle variatio
ns in microstructural constituents in lamellar and nearly lamellar TiA
l are found to have significant influences on the flow and fracture be
haviour.