Structure and phase evolution in Cu-Nb alloy under different types of mechanical alloying methods

Cu-10wt% Nb alloy powders were prepared via three different types of mechanical alloying (MA) methods: wet milling, dry milling as well as MA of pre-milled Nb and as-received Cu powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OP) techniques were used to investigate the phase and structure of the as-milled samples. The results show that the MA method affects the alloying process and the grain size refinement process significantly. The product prepared by wet milling shows the largest crystalline size and the lowest solid solubility extension of Nb in Cu. In contrast, the supersaturated Cu-10wt% Nb solid solution with the smallest crystallite size is obtained by MA of pre-milled Nb and as-received Cu powders. The MA process was discussed to explain the phenomena.