Modeling neck evolution and shrinkage during sintering of Astaloy® 85 Mo

Porosity and interparticle neck size are microstructural parameters that play an important role for pressed and sintered materials. To understand the effect of sintering parameters such as time and temperature on the microstructure of a pre-alloyed sintered steel (Astaloy® 85 Mo), a mean-field modeling approach tracking the neck size and geometry evolution during sintering is developed in combination with experimental studies. Building upon a mathematical framework describing the geometrical changes in a presently developed two-particle model, due to the diffusion mechanisms active during solid-state sintering, the influence of sintering conditions and of the initial microstructure on various aspects of the geometry is investigated. In addition, the predicted effects of each diffusion mechanism on different geometrical parameters are presented. To calibrate the model, the green-to-sintered dimensional change as well as experimentally observed microstructures of Astaloy® 85 Mo are also studied.