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| Mg–Gd–Y–Zn稀土镁合金应变调节机制研究 |
| Precise Measurement of Strain Accommodation in a Mg-Gd-Y-Zn Alloy |
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| DOI：10.3969/j.issn.1674-6457.2022.06.001 |
| 中文关键词: 应变调节 稀土镁合金 HR–EBSD 滑移转移 位错密度 |
| 英文关键词: strain accommodation Mg-RE alloy HR-EBSD slip transfer dislocation density |
| 基金项目:国家自然科学基金(51775135) |
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| Hits: 2012 |
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| 中文摘要: |
| 目的 在微观尺度上研究Mg–5.4Gd–1.8Y–1.5Zn合金的应变调节机制。方法 将拉伸试样变形至应变为6%，采用基于互相关分析的高分辨EBSD技术测量材料内部的刚体转动张量以及几何必需位错密度。结果 Mg–Gd–Y–Zn合金主要由基面<a>位错以及锥面<c+a>位错调节应变，即使在软取向晶粒内，锥面<c+a>位错也会大量出现。当发生基面–基面位错的滑移转移与基面–锥面位错的滑移转移时，相邻两晶粒滑移系之间的Luster–Morris因子很高(>0.78)。结论 随着不同滑移系施密特因子的升高，晶粒内的位错密度逐渐降低。这一反常现象可以归因于硬取向晶粒变形需消耗更多的应变能，而这部分应变能以位错密度的形式储存在晶粒内。 |
| 英文摘要: |
| Mg-RE alloys show improved ductility compared to other classical magnesium alloys at room temperature. The present study focused on the strain accommodation mechanism in a wrought Mg-5.4Gd-1.8Y-1.5Zn alloy at the microstructural scale. For this purpose, a tensile specimen was uniaxially strained in-situ to 6%, and the lattice rotation tensor and geometrically necessary dislocation (GND) density were measured using cross-correlation-based high angular resolution electron backscatter diffraction (HR-EBSD) technique. The strain incompatibility within the Mg-Gd-Y-Zn alloy was accommodated by basal slip together with pyramidal dislocation. The GND measurements via HR-EBSD showed a high occurrence of pyramidal <c+a> dislocation even in well-aligned grains. In addition, slip transfer process of the basal-basal and basal-pyramidal type was observed with high Luster-Morris factors (>0.78), in this study. The average GND density in grains tends to decrease with the Schmid factor increases. This phenomenon can be attributed to the fact that more strain energy is consumed for the hard-oriented grains, which is stored in grains in the form of dislocation density during deformation. |
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