Supersolidus sintering involves densification by liquid formation in a
prealloyed powder by heating above the solidus temperature. The criti
cal stage during densification is associated with the formation of a t
hreshold amount of liquid along the grain boundaries of a polycrystall
ine particle, leading to fragmentation and densification by a viscous
flow process. This paper covers model experiments involving the coales
cence of floating oil droplets dispersed with polymer grains that simu
late various solid-liquid ratios. Such experiments show that grain sli
ding occurs during fragmentation due to the presence of a shear stress
adjacent to the neck region. The threshold liquid content is determin
ed experimentally using a Ni-base alloy and stainless steel and these
results conform to earlier model predictions.