The correlation of microstructural development and thermal stability of mechanically alloyed multicomponent Fe-Co-Ni-Zr-B alloys

The microstructural evolution of multicomponent Fe70-x-yCoxNiyZr10B20 (x = 0, 7, 21: y = 7, 14, 21, 28) alloys during mechanical alloying (MA) has been studied using XRD. SEM and TEM. Mixtures of elemental and pre-alloyed powders have been transformed initially into the single supersaturated bcc alpha-Fe solid solution phase for the alloys investigated. Subsequently, an amorphous phase has been obtained in Co-free alloys and Co-containing alloys with high Ni/Co ratios of 1 and 3. However, no amorphous phase was detected in another Co-containing alloy with a lower Ni/Co ratio (e.g. 0.33). The thermal stability of the as-milled powders has been investigated by a combination of DSC and the Pendulum magnetometer experiments. The DSC studies provide information on the thermodynamics and kinetics of crystallization of amorphous structure as a function of alloying contents. The Pendulum magnetometer studies reveal the phase transformation from nanocrystalline bcc alpha-Fe solid solution to amorphous structure during MA and the thermomagnetization behavior of the as-milled powder. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.