Tensile creep anisotropy of a Mg-2Y alloy extruded sheet with a splitted texture

Abstract Mg-RE based alloys usually exhibit better creep resistance than traditional RE-free Mg alloys. Creep anisotropy can be still found in Mg-RE alloys but barely investigated. Thus, in the present study, tensile creep anisotropy and creep mechanisms were studied in a dilute Mg-2Y alloy extruded sheet. It is found that tensile creep property shows not only obvious stress and temperature dependences but also strong anisotropy. Varied stress exponent n is obtained under different conditions. Under σ   40 MPa at all temperatures, n > 4 is seen and intense dislocation slip becomes the predominant deformation mode. Besides, steady-state strain rate e ˙ s and n are always higher along ED than TD. This creep anisotropy is caused by different dislocation slip types. Basal slip plays the most important role in the creep anisotropy under σ   40 MPa. Heavy basal slip and pyramidal slip are the main mechanism during the creep along ED while cross-slip of dislocations plays the dominant role along TD. Furthermore, { 10 1 ‾ 2 } anomalous twins are more likely to be found in samples crept along ED with a smaller Schmid factor for twinning. Anomalous twinning and pyramidal slip contribute to the creep fracture of ED sample. Unlikely, cross-slip composed by basal and prismatic dislocations induces the fracture of TD sample.