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International Journal for Multiscale Computational Engineering

ISSN for PRINT: 1543-1649

Institutional price:	$747.00
Issues per year:	6

Best Paper Award Selection - Editorial Board Site

2003, Volume1

134 pages

DOI: 10.1615/IntJMultCompEng.v1.i1

Issue price - $178.00

Multiscale Modeling of Deformation and Fracture of Polycrystalline Lamellar g-TiAl + a₂-Ti₃Al Alloys

M. Grujicic
Department of Mechanical Engineering, Program in Materials Science and Engineering, Clemson University, Clemson SC 29634-0921

G. Cao
Department of Mechanical Engineering, Program in Materials Science and Engineering, Clemson University, Clemson SC 29634-0921

P. F. Joseph
Department of Mechanical Engineering, Program in Materials Science and Engineering, Clemson University, Clemson SC 29634-0921

ABSTRACT

The deformation behavior of fully-lamellar polycrystalline g-TiAl + a₂-Ti₃Al alloys has been analyzed using a finite element method. A three-dimensional rate-dependent, finite-strain, crystalplasticity based materials constitutive model is used to represent the deformation behavior of the bulk material. The constitutive behavior of g-TiAl/g-TiAl lamellar interfaces and lamellae-colony boundaries, on the other hand, are modeled using a cohesive-zone formulation. The interface/boundary potentials used in this formulation are determined through the use of atomistic simulations of the interface/boundary decohesion. The constitutive relations for both the g-TiAl + a₂-Ti₃Al bulk material and the lamellar interfaces and colony boundaries are implemented in the commercial finite element program Abaqus/Standard, within which the material state is integrated using an Euler-backward implicit formulation. The results obtained show that plastic flow localizes into deformation bands even at an overall strain level of only 0.5% and that incompatibilities in plastic flow between the adjacent colonies can give rise to high levels of the hydrostatic stress and, in turn, to intercolony fracture. Furthermore, it is found that when lamellar interfaces are admitted into colonies, fracture is delayed and the materials fail in a more gradual manner.