The recrystallization behavior of Al-6Mg-0.4Mn-0.15Zr-xSc (x=0.04-0.10 wt%) alloys

The recrystallization behavior of Al-6Mg-0.4Mn-0.15Zr-xSc (x = 0.04, 0.07, 0.10 wt%) alloys was studied using micro-hardness test, optical microscopy and transmission electron microscopy (TEM). The optical micrographs of the alloys with different Sc contents after being annealed at 100-550 degrees C for 1 h showed that the recrystallized nucleus formed between 275 and 325 degrees C at the original grain boundaries, and grew quite slowly until 550 degrees C and above, indicating a 250 degrees C large span of recrystallization starting and finishing temperatures in the alloys. The TEM observation showed the stripe distributed spherical Al-3(Sc,Zr) particles with phase rich region and phase poor region. The recrystallized subgrains with partial HAGBs was found at the phase poor region, but was pinned at the boundary of the phase rich region. The recrystallization driving and pinning pressures of the phase rich regions of the alloys with 0.04 and 0.1 Sc wt% were estimated according to Zener drag mode. The results indicated an effective pinning effect of Al-3(Sc,Zr) particles on the recrystallized grain at lower than 475 degrees C. The large span between recrystallization starting and finishing temperatures could be attributed to the stripe distribution of the Al-3(Sc,Zr) particles.