1995 Volume 36 Issue 4 Pages 548-554
Tumbler-ball milling experiment was carried out to investigate the change in particle morphology involved in the mechanical alloying of ductile metal powders using Cu powder as a model material. The morphological evaluation of the milled particles was traced by microscopic observations and by a shape analysis made on particle cross sections. It was found that during milling the particle shape of Cu powder changes from initial dendritie to disk-shape, then to coagulated pancake and eventually to large equi-axed globular particles.
The globular particles were found to be formed by agglomeration of the disk-shaped particles in a characteristic manner. It was also found that the large globular particles were formed by the agglomeration of the globular particles. The disk-shaped particles were supposed to be formed by breaking-off of sticked layer on ball surfaces and mill container walls by the impact actions of milling balls. The diameter of the disk-shaped particles estimated from the impact velocity of the balls based on the milling-ball dynamics and the Hertz contact theory is in good agreement with the measured one.