The principle of the particulate addition method
used for the present purpose is to heat a bed of sized
particles in an inert atmosphere and then to fluidize
and blow them, by means of an inert carrier gas, into
the melt through a nozzle. In the melt the particles are
uniformly distributed by breaking up the bubbles of
the fluidized mixture with the help of an impeller. The
schematic of the apparatus is shown in Fig. 2, and the
detailed description of the apparatus and its
operation is available elsewhere[3].
High purity HCT-20 grade TiBz powder (Ti =
68869% and B = 30-3 1%) was used for the present
purpose. This powder was supplied by Union
Carbide Coating Service Corp., Cleveland, OH. The
TIC powder (Ti = 80.0% and C = 19.8%) was
supplied by Kennametal Inc., Canada. The particle
size of TiB2 and TIC powders utilized here was in the