Dependence of compressive creep behavior on the loading direction of an extruded Mg sheet with an extremely dilute yttrium addition

In this work, the dependence of compressive creep behavior on loading direction was investigated using an extruded Mg sheet with an extremely dilute yttrium addition (0.2 wt%Y) and a split texture. The compressive creep tests were conducted at 393 K under applied stress ranging from 50 MPa to 100 MPa, with the loading direction parallel to the extrusion direction (ED), transverse direction (TD) and normal direction (ND), respec-tively. It was shown that the creep behavior of this dilute alloy had obvious dependence on the loading direction. The creep resistance ranked as a high-to-low sequence of ND > TD > ED. The creep mechanisms for all loading directions were revealed to be independence on the applied stress. Normal {1012} twinning, independent prismatic slip and pyramidal < c + a > slip were all detected in the ED sample. Differently, the TD and ND samples shared identical creep mechanisms, including anomalous {1012} twinning, cross-slip and pyramidal < c + a > slip. For the ED sample, the easy twin penetration and independent prismatic slip collaboratively conspired to the poor creep resistance. For the TD and ND samples, the successive work hardening induced by anomalous {1012} twins and the solute segregation at grain boundaries contributed to the high creep resistance. Although the creep resistance has long been thought to proportionate to the yield stress, this work discovered that the sample with low yield stress could possess high creep resistance in a TD-split texture. Henceforth, the findings are definitely helpful for the microstructure designs of heat-resistant Mg alloys.

Automated summary

This study investigates the dependence of compressive creep behavior on loading direction in an extruded Mg sheet with a dilute yttrium addition and a split texture. The results show that the creep resistance decreases in the order of ND, TD, and ED. The creep mechanisms also vary between different loading directions. The findings suggest that creep resistance is not solely determined by yield stress.