Effect of microstructure on the uniaxial tensile deformation behavior of Mg-4Y-3RE alloy

This paper reports microstructure-mechanical property correlations for a Mg-4Y-3RE (WE43) alloy. Friction stir (FS) processing was employed to modify the microstructure of hot-rolled (as-received) WE43 alloy. The grain size decreased from 10 to 300 µm in as-received condition to an average of 3.1±0.4 µm in FS processed condition. The alloy in AR condition contained globular, acicular, and rectangular (cuboidal) shaped precipitates located at twin boundaries, grain boundaries, and intragranular regions, along with fine scale honeycomb network of intragranular β1 precipitates. A very good combination of strength and ductility was observed for the alloy tested in FS processed condition. Detailed fractography was done to differentiate mode of fracture between as-received and FS processed conditions. Based on Schmid factor analysis, it was concluded that basal slip system controlled the yielding of the material in both the conditions. An empirical relationship was developed between work hardening rate and ductility. This can be applied to microstructural design of magnesium alloys used for applications where high uniform ductility is needed.