Effects of Yttrium Addition on Plastic Deformation of Rolled Magnesium

Abstract

Tensile tests were applied to rolled Mg-Y alloy sheets with various contents of yttrium 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 no more than 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 no more than 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.

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.