Dilute rare earth element mediated Hall-Petch relation of Mg alloys
Huihui Yu, Yanggang Li, Jiahao Wang, Bo Guan, Jing Xu
Abstract
Dilute rare earth (RE) element mediated Hall-Petch relation of Mg alloys has been investigated, with a focus on Mg-Y, Mg-Gd and Mg-Ce plate at an equivalent nominal solute content of approximately 0.1 at.%. Rare earth Mg plates under compression along the transverse direction (TD) exhibit a similar Hall-Petch response ( k values, 235.2, 266.4, 196.2 and 239.0 MPa μm 1/2 for Mg, Mg-Y, Mg-Gd, Mg-Ce plate, respectively) with Mg plate, similar to the friction stress for dislocations/twins movement within the grain. The mechanism for the similar texture dependence of k value is mainly related to the texture-induced variation of the predominant deformation. The dilute addition of RE element content with 0.1 at.% in this work is enough to cause a randomly distributed texture. Both the measured titling angle and maximum titling angle of the Mg-Y Plate, Mg-Gd Plate and Mg-Ce Plate are greatly larger than that of Mg plate. Under compression along the TD, a high activity of basal slip occurs, resulting in multiple types of adjacent grain pairs with different deformation modes transfer. The difference in activation stress and equivalent strain compatibility factor play pivotal roles in governing deformation transfer in RE Mg alloys, with texture serving as the primary mediator. Their values for Mg plate are in similarity with that for Mg-Y, Mg-Gd and Mg-Ce plate, contributing to a similar k value in the plate. The kind of 0.1 at.% RE element addition hardly affect k values. Dilute Mg-Ce alloy offers a cost-effective alternative to Mg-Y/Gd alloys for lightweighting applications. • Rare earth (RE) Mg plates exhibit a similar Hall-Petch response ( k ) with Mg plate. • The kind of RE element with 0.1 at.% addition hardly affects k values. • The dilute RE element addition is enough to cause a randomly distributed texture.