| 摘要 |
PURPOSE: To improve creep rupture strength by forming an Ni-base alloy of specific composition into single crystal by means of unidirectional solidification and then forming a structure consisting ofγ-phase,γ'-phase, and intermetallic compound. CONSTITUTION: A single crystal alloy, having an alloy composition consisting of, by weight ratio, 4.0-6.0% Al, 2.0-13.0% W, 2.0-9.0% Ta, 5.0-9.0% Cr, 1.0-6.0% Mo, 0.2-2.0% Re, 0.5-2.0% B, 0.5-2.0&C, and >=50% Ni, is prepared. Heat treatment is applied to this alloy to form a structure in which aγ'-phase composed essentially of Ni3 Al is precipitated in a single-crystal base phase ofγ-phase and also thisγ'-phase is enclosed with an intermetallic compound phase having a melting point higher than those of theγ-phase and theγ'-phase. At the time of manufacture, it is desirable to form an alloy ingot, in a polycrystalline state, into single crystal in a unidirectional solidification furnace and then perform solution heat treatment (heating, at 1300 deg.C), intermetallic compound precipitation treatment (heating, at 1150 deg.C), air cooling, two-stage aging treatment (heating, at 1080 deg.C and 870 deg.C), and air cooling.
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