Effects of Yttrium Addition on Plastic Deformation of Rolled Magnesium

Abstract

Tensile tests were applied to rolled Mg–Y alloy sheets with three at% of yttrium - Mg–0.54 at% Y, Mg–0.9 at% Y, and Mg–1.21 at% Y - to investigate effects of yttrium addition on activities of basal slip and non-basal slip systems so as to clarify the relationship between tensile properties and activities of slip systems. 0.2% proof stress of Mg–Y alloys increased with increasing yttrium content ranging from 0.5 to 1.2 at%. Ductility increased with increasing yttrium content until 0.9 at% but decreased when 1.2 at% was added. Frequencies of basal and non-basal slips increased by yttrium addition. The frequency of {1011} ⟨1123⟩ first order pyramidal slip (FPCS) increased with increasing yttrium content until 0.9 at% and decreased when 1.2 at% was added. With increasing yttrium content, the frequency of {1122} ⟨1123⟩ second order pyramidal slip (SPCS) decreased, while that of {1010} ⟨1120⟩ prismatic slip (PS) increased. The highest total frequency of non-basal slips was observed in Mg–0.9Y, showing the highest ductility. Enhancement of ductility on magnesium was caused by activation of both basal and non-basal slips through yttrium addition.

　

This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 84 (2020) 44–49.

Fig. 5 Optical micrographs of slip lines in 0.5Y-1 (ε = (a) 1.7% and (b) 5.5%) and 1.2Y-2 (ε = (c) 2.0% and (d) 5.2%). Slip lines were identified to be BS, PS, FPCS and SPCS using the trace analysis. I and II indicate connecting points of BS and FPCS, and BS and SPCS, respectively.