| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems with bulk of an oxide eutectoid which is usable for gas turbine blades for thermal power generator, the grain refining of which does not proceed because of a gentle temperature gradient (2 to 3 deg.C/mm) in a growth direction in a conventional method, or a Bridgman method, and has unsufficient strength. SOLUTION: The bulk of the oxide eutectoid is manufactured by an apparatus providing the bottom of an iridium metal or an iridium alloy crucible with a plurality of narrow pores, bringing the melt flowing down from these narrow pores into contact with the plane at the top end of the seed crystal to join the flows thereof, drawing out the joined melt downward by a seed crystal holder and solidifying and growing the melt unidirectionally. The homogeneous grain refining of the eutectic tissue is made successful by realizing the temperature gradient as steep as 150 deg.C/mm in maximum in the crystal growth direction and simultaneously realizing the homogeneous temperature distribution with respect to a radial direction. The practicable properties within the scope of 1,500 deg.C and 800 MPa in the atmosphere exceeding (about 5 times) conventional strength is obtained.
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