Twinning effects in deformed and annealed magnesium–neodymium alloys
Twinning effects in deformed and annealed magnesium–neodymium alloys
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DOI：
10.1016/j.msea.2015.08.090
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发表时间：
2015-10
期刊：
影响因子：
6.4
通讯作者：
Carsten Drouven;I. Basu;T. Al-Samman;S. Korte-Kerzel
中科院分区：
文献类型：
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作者：
Carsten Drouven;I. Basu;T. Al-Samman;S. Korte-Kerzel
摘要：对基织构弱{0001}< 11¯0>的Mg-1 wt% Nd合金进行了室温平面应变压缩（PSC）试验。平行于轧制板的平面内（IPC）和透厚（TTC）方向施加压缩载荷，以参与不同类型的变形孪晶。PSC分别达到6%和12%，然后将变形的试样在不同的高温下退火，以研究先前发育的孪晶的恢复和再结晶。利用x射线衍射、光学显微镜和电子背散射衍射技术对变形和退火织构和微观结构进行了表征。IPC和TTC作用下的变形表现为伸展和收缩孪晶的竞争性激活，并伴有均匀位错滑移。IPC高达6%的变形见证了上述两种孪生模式的同等激活，从而产生了软的和硬的纹理成分。TTC达到12%时呈现不太规则的基底型变形织构，其特征是在轧制方向上有较大的扩展，基底极在横向上约有- 5°和+ 25°的不对称分裂。退火过程中的织构演变与织构弱化有关，在相对较低的退火温度下（300°C）没有再结晶，保留了主要变形织构成分。强杂质阻力和颗粒钉住的存在将再结晶的发生推迟到325℃（TTC）和350℃（IPC），再结晶最好发生在压缩和双孪晶中。相关再结晶晶粒对基底滑移具有较高的施密德因子（SF），比与延伸孪晶或基体相关的竞争低施密德因子晶粒更大、更普遍。450℃时析出相的再溶解触发了晶粒的生长，导致与压缩和双孪晶相关的取向的强烈演化，这是在再结晶过程中出现的晶粒尺寸优势的结果。
Abstract Hot rolled Mg–1 wt% Nd alloy with a weak {0001}< 11 2¯ 0> basal texture was subjected to plane strain compression (PSC) at room temperature. Compressive loads were imposed parallel to the in-plane (IPC) and through-thickness (TTC) directions of the rolled plate in order to engage different types of deformation twins. PSC was conducted up to 6% and 12%, and the deformed specimens were subsequently annealed at different elevated temperatures to investigate recovery and recrystallization in the formerly developed twins. Deformation and annealing textures and microstructures were characterized using X-ray diffraction, optical microscopy and electron backscatter diffraction techniques. Deformation under IPC and TTC displayed competitive activation of extension and contraction twinning, supplemented by homogenous dislocation slip. Deformation in IPC up to 6% witnessed equal activation of both aforementioned twinning modes that gave rise to soft and hard texture components. TTC up to 12% exhibited a less regular basal-type deformation texture, characterized by a large outspread in the rolling direction, and an asymmetrical splitting of the basal poles around the transverse direction by about− 5° and+ 25°. Texture evolution during annealing was associated with general texture weakening, preserving the primary deformation texture components at relatively low annealing temperatures with no recrystallization (300° C). Presence of strong impurity drag and particle pinning delayed the onset of recrystallization till 325° C for TTC and 350° C for IPC specimens, which took place preferably inside compression and double twins. Related recrystallized grains possessed a high Schmid factor (SF) for basal slip, and were larger and more prevalent on average than competing low SF grains related to extension twins or the matrix. Re-dissolution of precipitates at 450° C triggered grain growth that led to strong evolution of orientations associated with compression and double twins as a result of a grain size advantage that emerges during recrystallization.