The time during which the compound remains in its
molten state is very short. For in-flight particles with a
velocity of 150 m/s and a substrate stand-off distance of
130 mm, the time is about ~0.85 ms. Owing to the short
existence time of the compounds in a molten state, the
diffusion is restricted. A part of the dissolved tungsten
could alloy substitutionally and form solid solution with
iron. As the tungsten-iron alloy starts to solidify, the
tungsten tends to form carbides, Fig. 11.
The arc heats the used wires, because of the thermal
conductivity of metals, in three different zones. Figure 12
clearly shows the three different arc heated zones of the
wires.