The exchange bias properties of ferromagnetic/antiferromagnetic (F/AF) bilayers depend strongly on both the F and AF bulk properties, and the interfacial uncompensated AF spins that magnetically couple the F and the AF materials. Whether it is possible to adjust the bulk properties of the AF layer by changing the nature of the AF material but without affecting the interface is one of the challenges raised by the development of some spintronic devices. In this context, we engineered composite AF materials whose basic composition is: (FeMn/Pt/AF). These structures are made of FeMn and IrMn alloys with the insertion of a thin Pt diffusion/trap barrier to Mn in order to ensure as much as possible the integrity of the AF layer at the interface. Magnetic measurements evidenced that, by changing the nature of the AF material, it remains possible to tune the thermal stability of the AF grains without affecting much the interface.