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Abstract

Precipitation of secondary phases in solid state is decisive for the mechanical
performance of many materials, or detrimental for other classes of materials. In most
cases precipitates show considerable mismatch in crystallographic structure and in
volume with respect to the matrix, which causes stresses and strain around the
precipitates. While solute diffusion is needed for the precipitates to grow, there will also
be an effect of the strain field on the diffusion if the volume and modulus of the matrix
depend on the concentration of solute. In the framework of the phase-field method the
connection between diffusion, growth and evolution of stress and superplastic relaxation
will be discussed. Examples are presented for pearlite growth in Iron-Carbon [1], grain
growth in nanomaterials controlled by vacancy diffusion [2] and stress driven solutal
depletion around ordered precipitates in Nickel-Titanium [3].

References

[1] I. Steinbach, M. Apel, The Influence of Lattice Strain on Pearlite Formation in
Fe-C"; Acta Materialia 55, 4817, 2007

[2] R. Darvishi Kamachali, J. Hua, I. Steinbach, A. Hartmaier, Multiscale simulations
on the grain growth process in nanostructured materials“; International Journal of
Materials Research Vol. 11, 1332, 2010

[3] W. Guo, I. Steinbach, C. Somsen, G. Eggeler, On the effect of superimposed
external stresses on the nucleation and growth of Ni4Ti3 particles – a parametric phase
field study, Acta Materialia, in press 2011