The mechanical behaviour of interpenetrating phase composites – II: a case study of a three-dimensionally printed material

The three-dimensional printing process allows the manufacture of components of complex shape. In the process, a binder is selectively sprayed onto layers of powder in a bed in sequence. Any unbound powder is removed from the component and the remaining powder is sintered to form the part. In producing parts for tooling, the porosity of the sintered powder is relatively high and is subsequently infiltrated with a second material, giving an interpenetrating phase composite in which each phase forms a completely interconnected network. In this paper, we describe an experimental and modelling investigation of the mechanical and thermal expansion properties of stainless-steel/bronze composites produced by three-dimensional printing. The properties are well-represented by non-linear finite element analysis based on a unit cell model with periodic boundary conditions. Numerical results show that the presence of thermal residual stresses and porosity contribute to a reduction in effective elastic moduli for these composites. These factors do not significantly affect flow or thermal expansion properties.