Microstructures and mechanical properties of extruded and heat treated Mg-6Zn-1Si-0.5Mn alloys

Si-rich intermetallic particles stabilize the fine grained microstructure in extruded Mg-6Zn-1Si-0.5Mn alloy, resulting in a yield strength (YS) of similar to 200 MPa, ultimate tensile strength (UTS) of similar to 310 MPa with an elongation of similar to 20%. Ca additions further refine the grain size leading to an increase in UTS by 30 MPa with no decrease in YS and elongation. The extruded Mg-6Zn-1Si-0.5Mn alloy can be age-hardened with the precipitation of fine [0 0 0 1](Mg) rod-like beta'(1) (Mg(4)zn(7)) particles and YS similar to 290 MPa and UTS similar to 320 MPa were achieved in the peak aged condition. The mechanical properties were further enhanced by pre-aging the alloy at 70 degrees C due to the refinement of the precipitate microstructure with YS similar to 350 MPa and UTS similar to 360 MPa. (C) 2012 Elsevier B.V. All rights reserved.