Improving creep property of Mg-Gd-Zn alloy via trace Ca addition

Only trace Ca addition to the Mg-2Gd-0.5Zn-0.2Zr (at.%) alloy leads to the precipitation of Guinier-Preston (GP) zones and remarkably improves the creep resistance at elevated temperatures. The Mg-2Gd-0.5Zn-0.4Ca-0.2Zr alloy exhibits a minimum creep rate of 5.75 x 10(-8)s(-1) tested at 250 degrees C and 110 MPa, its superior creep resistance is attributed to the precipitation of dense GP zones on the basal plane, increment in number density of refined 13 phases on the prismatic plane of the alpha-Mg matrix, narrow precipitate free zones (PFZs) and strengthened long period stacking ordered (LPSO) phases by trace concentration of Ca. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.