Mechanical Characterization of Cryomilled Al Powder Consolidated by High-Frequency Induction Heat Sintering

In the present investigation, an aluminum powder of 99.7% purity with particle size of similar to 45 mu m was cryomilled for 7 hours. The produced powder as characterized by scanning, transmission electron microscopy, and X-ray diffraction gave a particle size of similar to 1 mu m and grain (crystallite) size of 23 +/- 6 nm. This powder, after degassing process, was consolidated using high-frequency induction heat sintering (HFIHS) at various temperatures for short periods of time of 1 to 3 minutes. The present sintering conditions resulted in solid compact with nanoscale grain size (<100 nm) and high compact density. The mechanical properties of a sample sintered at 773 K for 3 minutes gave a compressive yield and ultimate strength of 270 and 390 MPa, respectively. The thermal stability of grain size nanostructured compacts is in agreement with the kinetics models based on the thermodynamics effects.