Authors: Yan Jun Li, Arild Håkonsen, Dag Mortensen, Tanja Pettersen, Trond Furu
Abstract: A simplified numerical model for the solid state phase transformation from Al6(Mn,Fe)
to α-Al(Mn,Fe)Si phase in 3xxx alloys has been constructed. In this model, the phase
transformation is assumed to be initiated by the heterogeneous nucleation of α-Al(Mn,Fe)Si
dispersoids at the interface between Al6(Mn,Fe) particle and matrix and the growth of the α-
Al(Mn,Fe)Si phase into the Al6(Mn,Fe) particle is controlled by the diffusion of Si from the matrix.
The model has been implemented into a numerical homogenization model. The simulation results
show that the implementation of the phase transformation model improves much the prediction
results of the homogenization model on the evolution of solid solution level of alloying elements
and the volume fraction evolution of dispersoids in 3xxx alloys during homogenization.
297
Authors: Christof Sommitsch, Peter Poelt, Guntram Rüf, Stefan Mitsche, Mihaela Albu
Abstract: In the high temperature deformation window of the nickel base Alloy 80A the lower
temperature region during open die forging was examined with regard to the materials formability.
For that purpose, hot compression samples were investigated by means of EBSD and TEM in order
to look at recrystallization, precipitations and ductile damage as well as their reciprocal effects.
Further a microstructure model was used, which calculates the materials strengthening, softening
and the particle kinetics. A micro mechanical damage model of the effective stresses was coupled
with the grain structure development in order to describe a retarded damage rate due to the ongoing
recrystallization.
2988
Authors: C. Schäfer, Günter Gottstein
Abstract: A refined view of particle stimulated nucleation of recrystallization is presented, which
utilizes a combination of advanced modeling tools. FEM simulations were carried out in order to
model the evolution of the deformation zone around particles for various particle sizes and shapes.
The results of these simulations were complemented by EBSD measurements to determine the
number and orientation of nuclei. Finally, this information on particle stimulated nucleation was
incorporated into a 3D cellular automaton recrystallization model CORe to model microstructure
evolution. From these simulations the dependence of grain size and texture on particles size and
shape was derived.
1169
Authors: Jiu Zhou Zhao, Qing Liang Wang
Abstract: Aging of Fe-Cu alloys or steels containing copper may result in the formation of the dispersion of nanometric precipitates in the matrix and, thus, causes a great increase in the strength of the alloys. A model is developed describing the aging process of Fe-Cu alloys. The model is first satisfactorily verified by comparing with the reported experimental results, and then applied to calculate the microstructure evolution during aging a Cu-Fe alloy. The numerical results demonstrate that the nucleation of the precipitates occurs after a period of incubation. Since that time on the microstructure evolution is the result of the concurrent action of nucleation, growth/shrinkage and structural transformation of the precipitates. In the late stage of aging almost all the precipitates are of 9R structure. The mean particle radius varies linearly with the cube root of time
164
