Ruangdaj Tongsri and Nattaya Tosangthum

pp. 209 - 214

Abstract

Solid state transformation of supersaturated solid solution to anomalous Ni-Sn eutectic has been studied. The metastable Ni-Sn solid solution was prepared via mechanical alloying of a mixed Ni+Sn powder containing 32.5 wt-% Sn powder.
The milling conditions included ball to powder ratio (BPR) of 5:1 and milling speed of 300 rpm. Milling times were varied as
5, 15, and 25 hours. Milling the mixed powder for longer than 15 hours resulted in formation of supersaturated Ni-Sn solid
solution. Differential thermal analysis of the supersaturated Ni-Sn solid solution revealed two reactions, namely peritectoid
and peritectic reactions, occurring at 945 and 1,141°C, respectively. Heating of the supersaturated Ni-Sn solid solution to
different temperatures such as 800, 850, 900, 950, 1,100, and 1,140°C with holding time of 10 minutes resulted in development
of anomalous eutectic with Ni₃
Sn phase matrix embedded with Ni solution particles. Sintering and coarsening of the eutectic
was depending on heating temperatures.