Influence of Processing Routes to Enhance the Mechanical Properties of Mg-6Zn-1Y-3.5CeMM (wt.%) Alloy

The microstructure and mechanical properties were investigated for Mg-6Zn-1Y-3.5CeMM (wt.%) alloy processed by extrusion at 400 degrees C of as-cast ingots (ACE alloy) or cold-compacted atomized powders (PME alloy). The use of fine-grained atomized powders results in a refinement of the microstructure, manifested by a reduced grain size and a smaller particle size with respect to the alloy processed by casting. The second-phase particles are the same for both W-phase (Mg3Zn3Y2) and T-phase (MgZnCeMM compound) particles, regardless of the processing route. The yield stress of the PME alloy at room temperature is not only increased by almost 40% compared with that of the ACE alloy (307 and 224 MPa, respectively), but the elongation to failure also increases to twice as much for the PME alloy. This differing mechanical behavior is related to the smaller grain size and the homogeneous distribution of the second-phase particles in the PME alloy. Up to 200 degrees C, both alloys maintain high mechanical strength, with UTS values remaining above 120 MPa. At high temperatures and low strain rates, deformation is controlled by grain boundary sliding, improving the ductility at the expense of a significant decrease in the yield strength of the ACE and PME alloys.