Numerical Modelling of SPS Process

Abstract : Spark plasma sintering is an electric current assisted powder compaction process. It consists in applying concurrently a pulsed current and a mechanical load to a specimen made of powder material. Different mechanisms are involved in the compaction process: thermally activated plastic deformation, sintering, and possibly electro-migration. This technology seems very promising to obtain net-shape components made of intermetallic alloys with a fine microstructure. However this process is problematic because of density heterogeneities arising from non homogeneous temperature or stress in the powder. This motivates the development of a three-dimensional finite element simulation in order to understand the distribution of current, temperature and porosity. The model couples three problems: electrical, thermal and mechanical. The code is based on a monolithic formulation consisting in solving the different equations on a single mesh including the specimen and the tooling. The different materials are identified by means of level set functions. An anisotropic remeshing around the interfaces between materials provides a smooth transition from one to another, specific mixing rules being used to define the physical properties. The general set of equations is described and first results involving electrical and thermal interactions are presented.