Microstructure evolution of TiB_（2） particle-reinforced 7075 Al alloy slurry in semisolid state with different holding time

摘要

TiB_2particle-reinforced 7075 Al alloy was synthesized to investigate the effect of TiB_2 particles on microstructure of semisolid 7075 Al alloy slurry. The mean grain size and shape factor of 3 wt% TiB_2/7075 composite could reach 92 lm and 0.64 at 630 °C for 23 min,respectively, and for 6 wt% TiB_2/7075 composite, they are100 lm and 0.64 at 630 °C for 33 min. The microstructure evolution for TiB_2/7075 composites in semisolid state includes three-stage process. a-Al begins to nucleate and grow up into rosette grains due to a low degree of supercooling at ?rst. Then rosette grains begin to fuse or grow up at different rates. Finally, the dissolution rate and the growth rate of α-Al reach equilibrium.