Three-dimensional structure observation method of inclusions and cracks

摘要

PROBLEM TO BE SOLVED: To provide an efficient and highly accurate observation method in a three-dimensional structure observation method of an enclosure and a crack for clarifying a breakdown phenomenon of metal starting from the enclosure.SOLUTION: A three-dimensional structure observation method of an enclosure 3 and a crack 4 includes: a primary observation step of observing, after forming a primary observation cross section P1 which forms an angle approximately in parallel with a rolling element rolling direction F and forms an angle approximately right angle to a rolling surface P by cutting and polishing it, the primary observation cross section P1 to specify positions of the enclosure 3 and the crack 4, directly under a rolling locus of a member subjected to rolling fatigue; a secondary observation step of continuously forming secondary observation cross sections P2 which form an angle approximately right angle to the rolling element rolling direction F at predetermined intervals to acquire continuous tomograms 6 by further using a converged ion beam; and an image processing step of three-dimensionally reconstructing the tomograms 6 to evaluate three-dimensional structure of the enclosure and the crack inside. The predetermined intervals for continuously forming the secondary observation cross sections P2 are within a range of 0.05-0.5 μm, acceleration voltage of the converged ion beam is within a range of 20-35 kV, and beam current is within a range of 0.5-10 nA.