A statistical analysis of compressive deformation mechanisms in an extruded Mg–3Y sheet

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-09, Vol.825, p.141927, Article 141927
• Main Authors: Hua, S., Jiang, Z.W., Wan, Y.F., Huang, G.H., Zhou, H., Zheng, J., Wang, Q.D., Yin, D.D.
• Format: Article
• Language: English
• Subjects: Compacting; Deformation mechanisms; Grain boundaries; Luster-morris parameter; Mechanical twinning; Mg alloy; Plastic deformation; Rare earth elements; Recrystallization; Room temperature; Schmid factor; Slip; Slip activity; Slip trace analysis; Statistical analysis; Strain analysis; True stress; Twin variant
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141927

A statistical analysis of plastic deformation mechanisms was performed on an extruded Mg-3 wt%Y sheet during room temperature uniaxial compression along the extrusion direction. Grain-scale slip trace analysis and twin variant analysis were performed grain-by-grain to reveal the active slip/twinning systems based on quasi-in-situ SEM and EBSD. The initial microstructure was fully recrystallized exhibiting typical rare-earth texture characteristics. The true stress-true plastic strain curve showed a sigmoidal shape indicating a profuse twinning activity which was consistent with the twin analysis. After 10% strain, there were 78 out of ~700 grains exhibited slip trace. In addition to the dominated basal slip (79.5%), considerable non-basal slips including 2nd pyramidal slip (11.5%) following prismatic slip (9%) were active. For twinning activity, among the ~250 grains analyzed at 10% strain, all the identified ~150 twins were tension twins with an area fraction of 19%. The twin variant selection did not solely follow the Schmid law, i.e. 42.3% twins exhibited low Schmid factor values (m0.75). However, the transmitted pairs with both large mnor sum and normalized m’ were preferred, and the fraction was over 64%. The twined number fraction was closely related to the maximum m values of prismatic slip. The present work implied that the twinning behavior is greatly dependent on the local conditions, and slip and twinning are closely related.