Control of structural refinement and composition in Al-MoO₃ nanocomposites prepared by arrested reactive milling

Al-MoO₃ nanocomposites were synthesized by arrested reactive milling (ARM) using powders of Al and MoO₃ as starting materials. Varying milling parameters lead to different scales of structural refinement in the nanocomposites. The objective of this work was to determine the range in which the degree of structural refinement can be changed in a controlled manner. The effect of structural refinement on the characteristics of these reactive nanocomposites was further investigated. The milling intensity was controlled by using different milling media along with varying amounts of process control agent (PCA). X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and wire-ignition tests were performed to analyze the Al-MoO₃ nanocomposites. Results indicate that the crystallite size decreased with increase in the milling intensity. However, increase in milling intensity also results in undesirable partial reaction between starting materials. Milling conditions resulting in the highest structural refinement and minimized partial reaction were identified. It was found that materials synthesized under the identified optimum conditions ignited at lowest temperature.