A new RHEED apparatus combined with a Si(Li) solid-state detector has been constructed, and spectroscopy of fluorescent X-rays emitted during RHEED observation has been carried out using the detector. Preliminary measurements have revealed the usefulness of this apparatus both for chemical analysis of surfaces and for investigating the behaviour of incident electrons in surface layers. When Ag thin films evaporated on a clean Si(111) surface were studied, the smallest detectable amount was about 0.02 Å in mean thickness. The penetration depth of the primary electron beam in the Ag film at an accelerating voltage of 20 kV was estimated to be 33.0 Å from analysis of the intensity of AgLα and AgLβ lines with increasing thickness of the Ag films.
The objective of the present paper is to clarify the effect of defect length in depth direction on rolling contact fatigue (RCF) crack propagation in high strength steel. RCF test and synchrotron radiation micro computed tomography (SR micro CT) imaging were conducted. In the case of the defect with the 15 ?m diameter, flaking life decreased with increasing defect length. In a comparison of the CT image and the SEM view, the shapes of defects and the locations of the horizontal cracks were almost the same respectively. The mechanism of RCF crack propagation was discussed by finite element (FE) analysis. Defects led to higher tensile residual stress than that without defects in the region where the defect exists. The shear stress range at 0.1 mm in depth on the middle line of the defect and the range of mode II stress intensity factor at the bottom of a vertical crack increased with increasing defect length.
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