The effects of process control agents on mechanical alloying behavior of a Fe–Zr based alloy

Abstract

In this work, a Fe–Zr based alloy prepared by MA was investigated. The as-milled powders were characterized using X-ray diffraction, differential scanning calorimetry, induction coupled plasma, chemical analysis and scanning electron microscopy. Analysis shows small contamination (<1.8 at.%) from the milling tools. In MA process, cold welding between particle and particle, and fracturing of the cold welded particles under high energy collision are involved. The balance between cold welding and fracturing can be controlled by the addition of a surface additive, a process control agent (PCA). Various PCAs such as: methanol, stearic acid, cyclohexane and PBTC were used. The results indicate that the impurities introduced by the PCAs may produce considerable effects on the thermally induced crystallization process as well as on the structural behaviour of the as milled powders, if compared with material synthesized without surfactant. We obtain materials with higher thermal stability and low crystalline size (∼6 nm). Nevertheless, in other samples the formation of a carbide and/or oxide phase or a high crystallite size (>60 nm) was found.