Interface instability of SiCf-reinforced superalloy matrix composites

Abstract

A number of recent reports indicate that SiCf-reinforced superalloy matrix composites show promise for increasing mechanical properties and lowering density. However, this has not yet been successfully demonstrated. The essence is the severe interfacial reaction. In present study, Ni, Fe, Co, Cr, Mo, 80Ni20Cr, 80Ni20Mo, 80Mo20Ni (in wt%), and Waspaloy-SiCf systems were fabricated. Interfacial reactions were analyzed by optical microscopy, field emission scanning electron microscopy and electron probe microanalysis. The results indicate that superalloy matrix elements Ni, Fe, and Co react violently with SiC, whereas strengthening elements Cr, and Mo, react mildly. Addition of other elements to form alloying systems including 80Ni20Cr, 80Ni20Mo, 80Mo20Ni and Waspaloy-SiCf fail to effectively suppress the severe reaction. Alloying could not suppress the reaction completely both in thermodynamic and kinetic. Matrix elements Ni, Fe, and Co dominate the reaction. Hence, the interface between superalloy and SiC fiber exhibits instability.