Precipitates evolution in the heat affected zone of Mg-Gd-Y-Zr alloy in T6 condition during laser welding

The precipitates evolution in the heat affected zone of laser-welded Mg-Gd-Y-Zr alloy in T6 condition was investigated based on the TEM observation. Some oval and long-rod shape precipitates along [2 (1) over bar(1) over bar0](alpha) were observed, which were not involved in precipitation sequence. Compared with isothermal aged precipitates, the overaged beta' phase presented same morphology and size, while size of needle-shape beta became much smaller. The width of complete dissolution zone of the beta' is smaller than that of partial dissolution and transformation zone.