Microstructural coarsening of 7005 aluminum alloy semisolid billets with high solid fraction

摘要: Abstract In the present study, 7005 aluminum alloy billets were supplied in warm extruded and T6 heat treated state. They then reheated to semisolid state microstructural evolution coarsening investigated. This is necessary groundwork if are be formed shape by processing, an innovative manufacturing route which has recently gained wide use for a range of alloys but not yet been applied 7005. The results showed that average spheroid size, liquid film thickness fraction increased with increase soaking time. Intragranular droplets solid grains, coarsened time isothermal temperature. roundness globules at 600 °C–615 °C was 1.5 2.0 after periods up 12 min 620 °C, times greater than 15 min more 2, unlikely suitable semi-solid forming process, where smooth flow required therefore relatively round globules. When temperatures 600 °C, 610 °C, 615 °C rates 542 μm 3  s − 1 , 606 μm 683 μm 688 μm respectively. rate K These values place this on dividing line between typical normally cast wrought alloys. attributed fact simple precipitation hardening system comparison other 7xxx precipitate (MgZn 2 ) melts below temperature experiments have carried out at, hence preventing precipitates inhibiting migration diffusion along narrow films boundaries. Coarsening tends occur via Ostwald ripening coalescence, plays increasing role