Abstract
The objective of this paper was to assess the coupling effect of vacuum, pressure and temperature on microstructure and mechanical properties of PM aluminum alloy. The results showed that the densification of PM aluminum alloy mainly depended on the powder plastic deformation caused by hot pressing, but the state of particle boundary (PB) was affected by vacuum besides temperature and pressure. When the powder was sintered under high vacuum of 10−3 Pa, the oxide film at PB could be disrupted by pressure, resulting in the formation of narrow regions of metal/metal contact. While under low vacuum of 10−1 Pa, the oxide film coarsened by secondary oxidation was unable to be broken by powder compressing, resulting in residual microcracks and segregation of second phases at the PB. This seriously weakened mechanical properties of PM aluminum alloy. The eutectic liquid formed by increased temperature would make the above process more complex.
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