@article{ModigellKoke1999,
  author    = {Michael Modigell and Johannes Koke},
  title     = {Time-Dependent Rheological Properties of Semi-Solid Metal Alloys},
  series   = {Mechanics of Time-Dependent Materials},
  volume    = {3},
  number    = {1},
  doi       = {10.1023/A:1009856708511},
  pages     = {15 -- 30},
  year      = {1999},
  abstract  = {Semi-solid metal alloys, as used in thixoforming, have a special microstructure of globular grains suspended in a liquid metal matrix. The complex rheological properties are strongly influenced by the local solid fraction, particle shape, particle size and state of agglomeration. There is a high demand for models and software tools allowing the simulation of semi-solid casting processes. The material under investigation is a tin-lead alloy (Sn-15\%Pb) which exhibits a similar microstructure to aluminium alloys. The experiments were performed with a concentric cylinder rheometer of the Searle type. Initially, the liquid alloy is cooled down to the semi-solid range under constant shearing and then kept under isothermal conditions for further experimentation. Based on the experimental data, a single-phase model has been derived where the semi-solid alloy is regarded as a homogeneous material with thixotropic properties and the microstructure is characterised by a structural parameter. The model consists of two parts: the equation of state, including a finite yield stress, and a rate equation for the structural parameter. The model equations are employed in numerical software and used for the simulation of characteristic filling cases and the comparison with the conventional filling.},
  language  = {en}
}