Experimental Characterization of Milling, Compaction and Sintering of Nanocrystalline FC-0205 Copper Steel Powder
The effect of ball milling on the compaction and sintering of nanocrystalline copper steel powder (FC-0205) was evaluated within this work. The as- received micron-sized FC-0205 copper steel powder were subjected to High Energy Ball Milling (HEBM) in an argon atmosphere at different milling times of 0, 16, 20 and 24 hours to obtain nanocrystalline structures. Unmilled, 8 and 16 hour milled powder specimen were compacted using uniaxial die compression at pressures ranging from 274 MPa to 775 MPa to obtain a relative density range of 74% to 95%, respectively. The steel powder compacts were sintered at temperatures ranging from 400 °C to 1120 °C in high purity hydrogen and nitrogen atmospheres. X-ray Diffraction (XRD) and microscopy analysis were performed on the milled powder specimens to evaluate the particle size, morphology, and extent of porosity; to establish a relationship between milling time and particle size; and to establish a correlation between grain size and milling time. Dilatometry analysis were performed on the compacts to examine the density and phase transformations of the specimens during sintering. As the mill time of the steel powder specimens increased, particle fragmentation increased, which resulted in particle size reduction and increased agglomeration of particles. The grain size of the steel powder specimens decreased as the mill time increased. An increase in density occurred as pressure increased. As temperature increased with mill time, compact density increased.
