Microstructural features induced by spray forming of a ternary Pb-Sn-Sb alloy

An alloy containing Pb-12% Sn-12% Sb with small addition of copper and arse nic was spray deposited employing two different atomization gas pressure an d nozzle to substrate distances. The temperature of the spray-deposit was m easured during deposition at a distance of 2 and 10 mm above the substrate- deposit interface. Thermal profile data indicated small variation in temper ature with time during deposition stage whereas during post deposition stag e an exponential decrease in temperature was recorded. Second phase particl e size along the thickness of the deposit varied from 4 to 8 mu m compared to 70 to 80 mu m size of these particles in the as cast alloy. Maximum poro sity occurred in the section of the deposit near the contact surface of the substrate and also in its peripheral regions. X-ray diffraction analysis e xhibited the formation of additional Cu2Sb phase in the spray-deposit and C uSn and Cu3.3Sb phases in atomized powders compared to that of the as cast alloy. The microstructural evolution during spray deposition of this alloy is discussed.