Study the effect of mechanical alloying parameters on synthesis of Cr2Nb–Al2O3 nanocomposite

In this study, Cr2Nb–20 vol.% Al2O3 nanocomposite was prepared successfully by mechanochemical reaction between Al, Nb and Cr2O3 powders. Amorphization of powder occurred during mechanical alloying because of high energy collisions between powders and steel balls in milling container which transfer high degree of energy to powders. Therefore, annealing was needed to form crystalline phases. The influence of different mechanical alloying parameters such as BPR, rotating speed, milling time and PCA concentration on synthesis of composite material were investigated. After mechanical alloying, the powder was encapsulated in quartz and then annealed at 1100 °C for 3 h. After annealing, 3 different phases were appeared (Cr2Nb (cubic), Cr2Nb (hexagonal) and α-Al2O3). The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).