Size effects in compression in Electron Beam Melted Ti6Al4V diamond structure lattices

In experimental work on the mechanical properties of stochastic metal foams, the consensus is that a minimum of six pores along each direction are required to give representative mechanical properties. This theory is tested for another porous metal, regular lattices, built using repeating unit cells of the diamond structure (a tetrahedral structure, in a cubic formation) by Electron Beam Melting (EBM) from grade 5 Ti6Al4V. Samples with different numbers of unit cells are made, using 3 different sets of EBM manufacturing conditions, and tested in compression. In all cases, a minimum of four unit cells are needed to ensure that size-independent mechanical properties are measured. Small changes in manufacture lead to large differences in properties.