{"title":"晶粒尺寸和塑性变形对恩氏铁锂辉石相变的影响:从原恩氏铁锂辉石向克氏铁锂辉石逆变过程中产生的微观结构中获得的启示","authors":"Miki Tasaka, Maya Iwago","doi":"10.1007/s00269-024-01294-5","DOIUrl":null,"url":null,"abstract":"<div><p>Enstatite (Mg<sub>2</sub>Si<sub>2</sub>O<sub>6</sub>) is a member of the pyroxene group and an important mineral in the lower crust and upper mantle. Enstatite has three phases at ambient pressure: protoenstatite, orthoenstatite, and clinoenstatite. Previously, the polymorphic transformation of pyroxene has been characterized using bulk techniques such as X-ray diffraction of powders. Given that rocks are crystal aggregates, it is important to use aggregates to understand phase transformations. We therefore conducted grain growth and deformation experiments using aggregates of enstatite to investigate phase transformations. Grain growth experiments were conducted at temperatures (<i>T</i>) of 1345 and 1360 °C under a vacuum of ≈ 10 Pa using an alumina tube furnace. Deformation experiments were conducted at <i>T</i> = 1310 °C and room pressure, a strain rate of ≈ 10<sup>–4</sup> s<sup>–1</sup>, and a resulting stress of ≈ 150 MPa. The samples were analyzed using a scanning electron microscope, electron backscatter diffraction (EBSD), and X-ray diffraction. The results indicate that the grain size affects the transformation from protoenstatite to clinoenstatite, whereas deformation by diffusion creep does not. The EBSD analyses show that the volume fraction of clinoenstatite increases with increasing grain size. The samples underwent diffusion creep during the deformation experiments, and there were no distinct microstructural differences between deformed and undeformed samples. The EBSD analyses show that the transformed clinoenstatite has a characteristic twin structure with a misorientation angle of 180° and a rotation axis of [100] or [001]. Grain sizes become smaller during the phase transformation, even if the mechanism can be characterized as a second-order transformation.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":null,"pages":null},"PeriodicalIF":1.2000,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01294-5.pdf","citationCount":"0","resultStr":"{\"title\":\"Influence of grain size and plastic deformation on the phase transformation of enstatite: insights from microstructures produced during the back-transformation of protoenstatite to clinoenstatite\",\"authors\":\"Miki Tasaka, Maya Iwago\",\"doi\":\"10.1007/s00269-024-01294-5\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Enstatite (Mg<sub>2</sub>Si<sub>2</sub>O<sub>6</sub>) is a member of the pyroxene group and an important mineral in the lower crust and upper mantle. Enstatite has three phases at ambient pressure: protoenstatite, orthoenstatite, and clinoenstatite. Previously, the polymorphic transformation of pyroxene has been characterized using bulk techniques such as X-ray diffraction of powders. Given that rocks are crystal aggregates, it is important to use aggregates to understand phase transformations. We therefore conducted grain growth and deformation experiments using aggregates of enstatite to investigate phase transformations. Grain growth experiments were conducted at temperatures (<i>T</i>) of 1345 and 1360 °C under a vacuum of ≈ 10 Pa using an alumina tube furnace. Deformation experiments were conducted at <i>T</i> = 1310 °C and room pressure, a strain rate of ≈ 10<sup>–4</sup> s<sup>–1</sup>, and a resulting stress of ≈ 150 MPa. The samples were analyzed using a scanning electron microscope, electron backscatter diffraction (EBSD), and X-ray diffraction. The results indicate that the grain size affects the transformation from protoenstatite to clinoenstatite, whereas deformation by diffusion creep does not. The EBSD analyses show that the volume fraction of clinoenstatite increases with increasing grain size. The samples underwent diffusion creep during the deformation experiments, and there were no distinct microstructural differences between deformed and undeformed samples. The EBSD analyses show that the transformed clinoenstatite has a characteristic twin structure with a misorientation angle of 180° and a rotation axis of [100] or [001]. Grain sizes become smaller during the phase transformation, even if the mechanism can be characterized as a second-order transformation.</p></div>\",\"PeriodicalId\":20132,\"journal\":{\"name\":\"Physics and Chemistry of Minerals\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.2000,\"publicationDate\":\"2024-08-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://link.springer.com/content/pdf/10.1007/s00269-024-01294-5.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Physics and Chemistry of Minerals\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s00269-024-01294-5\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"MATERIALS SCIENCE, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Minerals","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s00269-024-01294-5","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
黝帘石(Mg2Si2O6)是辉石类的一种,也是下地壳和上地幔中的一种重要矿物。在常压下,恩氏闪长岩有三相:原恩氏闪长岩、正恩氏闪长岩和克利诺恩氏闪长岩。以前,人们使用粉末的 X 射线衍射等大块技术来描述辉石的多晶体转变。鉴于岩石是晶体聚集体,利用聚集体来了解相变非常重要。因此,我们利用辉石聚集体进行了晶粒生长和变形实验,以研究相变。晶粒生长实验是在 1345 和 1360 °C 的温度(T)下,利用氧化铝管式炉在≈ 10 Pa 的真空条件下进行的。变形实验是在 T = 1310 °C 和室压下进行的,应变速率为 ≈ 10-4 s-1,产生的应力为 ≈ 150 MPa。使用扫描电子显微镜、电子反向散射衍射(EBSD)和 X 射线衍射对样品进行了分析。结果表明,晶粒尺寸会影响原芒硝向克氏芒硝的转变,而扩散蠕变变形则不会。EBSD 分析表明,随着晶粒尺寸的增大,闪长岩的体积分数也随之增大。样品在变形实验过程中发生了扩散蠕变,变形样品和未变形样品之间没有明显的微观结构差异。EBSD 分析表明,转变后的闪长岩具有特征性的孪晶结构,错向角为 180°,旋转轴为 [100] 或 [001]。在相变过程中,晶粒尺寸变小,即使其机理可定性为二阶转变。
Influence of grain size and plastic deformation on the phase transformation of enstatite: insights from microstructures produced during the back-transformation of protoenstatite to clinoenstatite
Enstatite (Mg2Si2O6) is a member of the pyroxene group and an important mineral in the lower crust and upper mantle. Enstatite has three phases at ambient pressure: protoenstatite, orthoenstatite, and clinoenstatite. Previously, the polymorphic transformation of pyroxene has been characterized using bulk techniques such as X-ray diffraction of powders. Given that rocks are crystal aggregates, it is important to use aggregates to understand phase transformations. We therefore conducted grain growth and deformation experiments using aggregates of enstatite to investigate phase transformations. Grain growth experiments were conducted at temperatures (T) of 1345 and 1360 °C under a vacuum of ≈ 10 Pa using an alumina tube furnace. Deformation experiments were conducted at T = 1310 °C and room pressure, a strain rate of ≈ 10–4 s–1, and a resulting stress of ≈ 150 MPa. The samples were analyzed using a scanning electron microscope, electron backscatter diffraction (EBSD), and X-ray diffraction. The results indicate that the grain size affects the transformation from protoenstatite to clinoenstatite, whereas deformation by diffusion creep does not. The EBSD analyses show that the volume fraction of clinoenstatite increases with increasing grain size. The samples underwent diffusion creep during the deformation experiments, and there were no distinct microstructural differences between deformed and undeformed samples. The EBSD analyses show that the transformed clinoenstatite has a characteristic twin structure with a misorientation angle of 180° and a rotation axis of [100] or [001]. Grain sizes become smaller during the phase transformation, even if the mechanism can be characterized as a second-order transformation.
期刊介绍:
Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are:
-Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.)
-General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.)
-Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.)
-Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.)
-Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems
-Electron microscopy in support of physical and chemical studies
-Computational methods in the study of the structure and properties of minerals
-Mineral surfaces (experimental methods, structure and properties)