REACTION-RATES DURING MECHANICAL ALLOYING

This paper presents a simple kinetic model of the coalescence and fracturing events that occur during mechanical alloying (MA). The model is based on reaction kinetics based on times between powder particle collisions and particle specific probabilities of welding and fracture. The model is combined with experimental studies and previous models of the MA process to provide information relative to the welding and fracturing probabilities of the various particle species involved. We find that, during MA of Cu-Nb alloys in an attritor, the probability of welding for copper particles is approximately one in 2000 for a ball-to-powder charge ratio of 50 to one. Decreasing the charge ratio decreases the probability of particle welding and lengthens the milling time neccessary for alloying.