Abstract. The phase boundary between wadsleyite and ringwoodite in Mg2SiO 4 composition was determined by in situ observation using synchrotron X-ray and multi anvil apparatus in KEK, Tsukuba, Japan. An energy dispersive method was employed using the Ge solid state detector and the white X-ray beam from the synchrotron radiation source. The pressure was determined by the equation of state of NaCl. The stability field was identified by the change in intensities of diffraction lines of each phases. As a result, the phase boundary is expressed as a linear equation P=I0.32(28)+0.00691(9)xT, where P is pressure in gigapascals and T is temperature in degrees Celsius.
IntroductionOlivine is the major constituent in the Earth's upper mantle, and the significant seismic discontinuities, which locate 400 km and 670 km deep, are considered to be caused by the phase transition of olivine to wadsleyite (modified spinel structure) and the decomposition of ringwoodite (spinel structure) to magnesiowustite and There are a number of quench experiments so far on the phase boundary between wadsleyite and ringwoodite [e.g., Kawada, 1977; $uito, 1977;Katsura and Ito, 1989], however, the in situ X-ray determination have not been conducted yet.In the quench experiments, pressure was estimated from the calibration curve, which is based on the fixed point at room and/or high temperatures, and the considerable uncertainty remains in pressure (e.g., +I.5GPa above 14 GPa
The maximum size of single inclusion particles and clusters in an Fe-10 mass% Ni alloy deoxidized with Al or Ti/Al were examined using extreme value analysis. The results obtained from conventional twodimensional observations of inclusions on a polished cross section of metal sample (the CS-method) were compared to those from three-dimensional investigations of inclusions on a film filter after electrolytic extraction (the EE-method). It was found that the EE-method can successfully be used as a reference method for estimation of the probable maximum size of single inclusion particles and clusters by using an extreme value distribution (EVD). The EVD results for single inclusion particles obtained from the EEmethod agreed satisfactorily well with those from a conventional CS-method. However, this required identification as well as neglect of pores on an investigated cross section of a metal sample. The predicted maximum size of single inclusion particles in a 1 mm 3 volume was confirmed by results from the EEmethod.
The statistics of extreme values was applied for the determination of the largest sulfide inclusions with different morphology in low carbon steel samples by using both two‐dimensional (2D) observations on the polished cross section and three‐dimensional (3D) observations on a surface of a film filter after electrolytic extraction of the samples. It was found that the globular, rod‐like and dendritic sulfides in the molten steel sample as well as the elongated sulfides in the rolled steel sample can be successfully extracted from the both samples, and analyzed precisely by using extreme value analysis in 3D. Based on the geometrical considerations of the probability for measurement of the true length of rod‐like and elongated inclusions on a cross section, it was found that this probability for inclusions decreases dramatically with an increasing real aspect ratio value of them. Particularly for the determination of the true length for elongated inclusions in the rolled steel sample by 2D investigations on a metal cross section, it is required to be cut investigating section of steel sample within ± 1 degree against rolling direction. Therefore, a 3D observation is considered to be more preferable and accurate than the conventional cross sectional observation in 2D, due to the possibility for the measurements of the real size of them.
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