Composite materials, consisting of a TRIP/TWIP steel matrix (X5 CrNi 18-10) and a varying ceramic particle addition as reinforcement, were processed by SPS. Alumina or alumina and Mg-PSZ (MgO-partially stabilized zirconia) were used as reinforcement. Both, the TRIP-steel and the Mg-PSZ have the ability to undergo a martensitic phase transformation, which is deformation induced and strain induced, respectively. These phase transformations enhance the strength and the toughness of the material. For the materials processing, two different routes were studied. During one route, the alumina was locally concentrated in some steel particles while other steel particles remained unreinforced. With the second processing route the reinforcement was homogeneous distributed within the steel matrix. Through the particle reinforcement combined with the phase transformations and a suitable processing route, a composite with a maximum compressive strength of 1600MPa was processed. This composite had a sufficient ductility of 50% true compressive strain.