GEOMETRY OF RAPIDLY SOLIDIFIED RIBBONS FOR MILITARY APPLICATIONS

This work aims to study the influence of processing variables in melt spinning - which is one of the rapid solidification processes (RSP) - on the geometry of the ribbons produced directly from the melt. The R5P is one of the recent manufacturing techniques, in which the final products - ribbons and fibers - could be produced directly by solidification of liquid alloys, thus saving all further conventional metal forming processes usually carried out. In this investigation, a melt spinning apparatus was designed and con-structed in order to produce ribbons from the melt using a rotating substrate in the form of wheel. The alloys studied were aluminium alloys with 0, 5.23, 13.46 and 33 wt% Cu. The processing variables used were as follows: substrate linear velocity (v) ranging from 2 to 20 m.sI, injection pressure of the melt (P) ranging from 2.9 X 104 to 6.8 X 104 N.m-2, substrate thermal conductivity (K) ranging from 43.3 to 386.6 W.m-I.K-1, melt superheating temperature ( AT) ranging from 0 to 150 K, nozzle - substrate distance 0-0 ranging from 5 to 20 mm and nozzle diameter (d) ranging from 0.5 to 2 mm. The geometry of the product; ribbon thickness (t), width (w), length (L) and surface roughness (Rt) have been measured and they were correlated with the different process-ing variables.
It is found that v plays the most important role in determining the geometry parameters, where a critical velocity of 5 m.s 1 is found. Varying v up to this value causes increase in w and L and a decrease in t. Increasing v beyond this value causes decrease in w, L and t.