The interaction between SiC and Ni, Fe, (Fe,Ni) and steel : morphology and kinetics

The interaction between SiC and metals based on Ni or Fe has been studied from a thermodn. and kinetic point of view. The reactions were studied in solid-state diffusion couples at 700-1035 Deg. In SiC-Ni couples the phases Ni2Si, Ni5Si2 and Ni3Si are formed. The carbon is present as ppts. in regular bands in the Ni2Si and Ni5Si2 layers. In SiC-Fe couples the layers consist of a-(Fe,Si) with random carbon ppts. In SiC-FexNi100-x couples at 850 Deg a variety of phases has been found. Dependent on the value of x, a-(Fe,Ni,Si), g-(Fe,Ni,Si), (Fe,Ni)5Si2, (Fe,Ni)2Si and the ternary phase t-(Fe5Ni3Si2) are formed. Carbon is present, either as isolated particles (in Fe-rich layers) or in regular bands (in Ni-rich layers). The reaction zone in SiC-steel 316 couples consists of Fe silicides, Ni silicides, Cr carbides, Cr silicides, Mo silicides and Mo carbides. The kinetics of the SiC-(Fe,Ni) reactions are not simply intermediate between the kinetics of SiC-Ni and SiC-Fe. The reaction layer in SiC-steel couples stops growing after a short time. This is attributed to the formation of the chromium carbides. [on SciFinder (R)]