材料期刊网

We have found that phase transformation can occur in cobalt when subjected to ball milling. The two modifications of cobalt, i.e. face-centered-cubic (fcc) and hexagonal close-packed (hcp) phases, which usually coexist at room temperature and are often difficult to be separated from each other can now be easily separated by using the simple ball milling technique. The phase formation of cobalt is found to depend on the mill intensity. With different mill intensities or different milling times, single fcc phase, single hcp phase or fcc+hcp phases have been formed. Our results indicate that the phase formation of cobalt induced by ball milling is determined by the accumulation of structure defects and not by the focal temperature vise. Different mill intensities may adjust the rare and level of the accumulation of defects.