Formation of Ni-MgO composite microstructures by displacement and partial reduction reactions

Metal-ceramic microstructures were produced by two different approaches: a displacement reaction between Mg and NiO and a partial reduction reaction starting with a solid solution of (Mg,Ni)O. In both cases Ni-rich particles were embedded in a Mg-rich (Mg,Ni)O ceramic phase. For the displacement reaction, the two phase structure is produced during hot pressing. For the partial reduction reaction, individual ceramic grains are first reduced to a two phase mixture and then hot pressed to form a monolithic solid. The size and distribution of the Ni particles are controlled by the reduction conditions. The different reactions and reducing conditions produce different two phase microstructures. The mechanical properties are related to the morphologies of the different microstructures.