FERRITE NUCLEATION AT CERAMIC AUSTENITE INTERFACES/

Pure polycrystal ceramics (TiC, TiN, TiO, VN, AlN and Al2O3) were heat -pressure-bonded to an Fe-0.1 mass%C-2mass%Mn alloy and were isotherma lly reacted below the Ae(3) temperature for the proeutectoid ferrite r eaction to occur. The number of ferrite particles per unit area of bon ded interfaces was measured using Schwartz-Saltykov method and was com pared with the number of particles formed at grain boundaries. VN was most effective in Stimulating ferrite nucleation whereas TiO was least effective. All other ceramics showed more or less similar potencies f or ferrite formation. VN is capable of forming lower energy interfaces with ferrite than other ceramics, though the possibility of V diffusi on into the alloy during and after bonding may not be ruled out in thi s experiment. On the other hand, the least effectiveness of TiO in sti mulating ferrite nucleation is possibly due to the proximity of therma l expansion coefficient to iron.