发表机构
GFZ Helmholtz Centre for Geosciences; RWTH Aachen University（GFZ德国地球科学研究中心; 亚琛工业大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用微柱压缩实验定量测量了钙长石不同滑移系和机械孪晶的强度，发现孪晶最易激活，滑移强度随温度变化，为理解地壳流变提供了关键数据。
AI 中文摘要
斜长石是地壳中最丰富的矿物族，因此它将控制或强烈影响地壳流变学。然而，由于在大多数实验室条件下脆性变形占主导地位，我们对斜长石晶体塑性仍知之甚少。为了克服过去在定量研究斜长石晶体塑性变形方面的挑战，我们采用微柱压缩法来量化特定滑移系的强度以及钙长石中机械孪晶所需的应力。利用聚焦离子束，从同一钙长石单晶的三个不同取向切割面上铣削出直径约1微米的微柱。随后，在扫描电子显微镜内，对总共36根微柱进行了单轴变形实验，实验温度分别为25、300或800摄氏度。大多数微柱以恒定位移速率变形，对应的应变速率约为0.001 1/s。我们发现，机械（pericline）孪晶的临界分解剪切应力（CRSS）约为300 MPa，并且正如先前对其他材料的研究所预期的那样，该应力对温度或应变速率的变化不敏感。在取向设计为激活滑移的晶体中，微柱变形表现出屈服应力随温度升高而显著降低。在微柱变形过程中活跃的变形机制中，在所施加条件下孪晶最容易发生，其次是（011）[100]滑移，且与温度无关。在我们的钙长石微柱中，（011）[0-11]或（0-11）[011]滑移始终是最难激活的机制。
英文摘要
Plagioclase is the most abundant mineral group of the crust and will therefore either control or strongly influence crustal rheology. Yet, we still know little about crystal plasticity in plagioclase as brittle deformation dominates under most laboratory conditions. To overcome past challenges in quantifying crystal plastic deformation in plagioclase, we used micropillar compression to quantify the strength of specific slip systems as well as the stresses necessary for mechanical twinning in anorthite. Pillars with diameters of around 1 micrometre were milled from three differently oriented cuts of the same anorthite single crystals using focused-ion beam. Uniaxial deformation of 36 pillars in total was then conducted inside a scanning-electron microscope under either 25, 300, or 800 degrees Celsius. Most pillars were deformed with a constant displacement rate that corresponds to a strain rate of around 0.001 1/s on the pillars. We find that the critical resolved shear stress (CRSS) for mechanical (pericline) twinning lies at around 300 MPa and is, as expected from previous studies on other materials, insensitive to changes in temperature or strain rate. Pillar deformation in crystals oriented to activate slip exhibit a strong decrease in yield stress with increasing temperature. Among the deformation mechanisms active during pillar deformation, twinning is the easiest under the applied conditions, followed by slip on (011)[100] regardless of temperature. Slip on (011)[0-11] or (0-11)[011] is consistently the hardest mechanism to activate in our anorthite pillars.
Comments37 pages, 13 figures
