The aim of this work is to investigate the interaction of basal dislocations and twin boundaries with ultrafine basal disk-shaped precipitates at the atomic scale in the peak-aged Mg-1Mn-1Nd-3Zn (wt.%) alloy. With that goal, an experimental approach consisting on micropillar compression of two grains oriented favorably for basal slip and for tensile twin activation, respectively, as well as high resolution transmission electron microscopy, was put in place. First, a novel mechanism of interaction between particles and basal dislocations was observed. In particular, the movement of dislocations along basal planes led to the dissolution of the ultrathin basal precipitates in the nearby regions (within 80 nm) and to solute diffusion resulting in microsegregation of solutes at the slip lines. Hindering of basal slip due to such microsegregation prevented slip localization by promoting the consecutive activation of softer basal planes. Second, twin-precipitate interactions were found to be dependent on the twin boundary plane. In particular, bypassing of precipitates by coherent twin boundary segments were observed to lead to elastic rotations of the precipitate lattice, while the interaction of CTB/prismatic-basal intersections with precipitates resulted in precipitate shearing along prismatic planes.

这项工作的目的是在峰值时效 Mg-1Mn-1Nd-3Zn (wt.%) 合金中研究原子尺度上的基底位错和孪晶界与超细基底盘状沉淀物的相互作用。为了这个目标，一种实验方法包括对两个晶粒进行微柱压缩，这些晶粒分别有利于基底滑移和拉伸孪晶活化，以及高分辨率透射电子显微镜。首先，观察到粒子和基底位错之间相互作用的新机制。特别是，位错沿基面的移动导致附近区域（80 nm 内）中超薄基底沉淀物的溶解和溶质扩散，导致溶质在滑移线处发生微偏析。由于这种微偏析而阻碍基底滑移，通过促进较软基底平面的连续激活来防止滑动定位。其次，发现双沉淀相互作用依赖于双边界平面。特别是，观察到相干孪晶边界段绕过沉淀物会导致沉淀物晶格的弹性旋转，而 CTB/棱柱形基底相交与沉淀物的相互作用导致沉淀物沿棱柱面剪切。