By mixing ferritic and austenitic powder grades into the desire proportion can be produced a tailored duplex stainless steels (DSS). In this case, when austenite is less than 50%wt materials shown net duplex microstructures. But when austenite presence is higher than ferrite appears a phase at interface due to Ni and Cr diffusion at particles boundaries, which modify all the properties. Based on phase diagrams, this phase is a fine DSS microstructure as a consequence of gradient of Ni concentration from austenite to ferrite particle. The objective of this work is to obtain, as much as possible, a fine DSS microstructure as Ni homogenisation increases. Therefore, to favour diffusion mechanism it has been acted in three directions: by increasing the sources of Ni adding an austenite powder grade with lower particle size that increased the active surface; increasing the sintered time and performing solution heat treatments with the aim of achieve a longer Ni homogenisation. For this purpose, by mixing ferritic-austenitic stainless steels grade powders has produced a duplex stainless steel, compacting at 700 MPa uniaxially and sintering in vacuum at 1250degreesC for 180 min. The cited interface has been studied by SEM and light optical microscopy (LOM) as well as its influence on mechanical properties.