The nucleation of microvoids from second phase particles in an AlMgSi
alloy has been investigated. The work has comprised detailed stress an
alyses of elastic particles situated in an elastic-plastic matrix as w
ell as damage mechanics analyses of the ductile fracture behaviour of
smooth and notched axisymmetric tensile specimens. Based on the microm
echanical analyses of isolated particles, general expressions relating
local stresses in the particles to the stresses on a mesoscopic (cont
inuum) level have been derived. These relationships have been incorpor
ated into the classical Gurson model. Combined with a failure criterio
n based on a physical coalescence mechanism, a calibration with experi
mental results enabled the establishment of a set of micromechanical p
arameters which are transferable between different stress triaxialitie
s.