Mg?RE挤压合金晶体学织构与力学性能各向异性分析

Analysis of Crystallographic Texture and Mechanical anisotropy of an Extruded Mg?RE alloy

摘要:

本论文研究了热挤压加工对Mg-1Gd-1Nd (wt.%)合金显微组织、织构及力学性能的影响。研究结果表明,铸态合金呈现典型的共晶显微组织,包含α-Mg基体及半连续状的共晶化合物。经过固溶热处理后,这些共晶化合物已基本固溶入α-Mg基体中。采用电子背散射衍射(EBSD)技术分析了挤压合金的显微组织与织构。结果表明,挤压合金显示出了完全再结晶的显微组织与弱的基面织构。合金中的晶粒基面同时朝向挤压板材的挤压方向与垂直方向偏移,尤其在挤压方向上晶粒的取向更加分散。这种分散的取向可以有效地激活合金中的基面滑移使得合金在断裂前能够承受更大的塑性变形。另一方面,织构也影响了合金力学性能的各向异性。

Abstract:

In present work, the impact of hot extrusion on the microstructure and texture, as well as mechanical properties of the Mg?1Gd?1Nd (wt.%) alloy were investigated. The results demonstrated that the as-cast alloy displayed a typical eutectic microstructure consisting α-Mg solid solution and semi-continuous eutectic compounds. After solution treatment, the eutectic compounds were mostly dissolved in the α-Mg matrix. The microstructure and texture of the extruded alloy were analyzed by electron backscatter diffraction (EBSD) technique. It was demonstrated that the extruded alloy exhibited fully recrystallized microstructure and weak basal texture. In details, the basal planes of the grains majority were spread both towards extrusion direction and transverse direction of the extruded alloy sheet. Especially in the extrusion direction, the orientation distribution was significantly dispersive. The broad spread in orientations resulted in effective activation of the basal slip and allows the alloy to accommodate higher strains prior to failure. On the other hand, the texture was responsible for the planar anisotropies of the extruded alloy sheet.