The morphology and growth kinetics of cellular precipitation and disco
ntinuous coarsening of cellular precipitates have been studied in two
Ni-In alloys containing 4 and 6 at.% Tn in the temperature range 740 t
o 1010 K. The data for 2 and 8 at.% In alloys have been taken from ear
lier investigations [1, 2]. Growth rate measurements were carried out
utilizing optical microscopy. Both optical micros copy and scanning el
ectron microscopy were utilized for interlamellar spacing measurements
. All alloys were observed to decompose completely by the cellular pre
cipitation reaction into a lamellar structure consisting of alternate
lamellae of the alpha and Ni3In phases at all aging temperatures. The
fine lamellar structure of the primary cells decomposed into a coarse
lamellar structure consisting of the same two phases. The primary and
secondary cell growth data were analysed by using model after Peterman
n and Hornbogen. From the diffusivity values, it has been concluded th
at the growth of primary and secondary cells occurs by diffusion of Tn
along the grain boundaries. The rate of migration of the reaction fro
nt for both cellular precipitation and discontinuous coarsening is inc
reased markedly with increasing In content.