| 摘要 |
A cobalt base alloy having a superior high-temperature strength and high-temperature ductility, containing, by weight, 0.15 to 2% carbon, less than 2% silicon, less than 2% manganese, 5 to 15% nickel, 18 to 35% chromium, 3 to 15% tungsten, 0.003 to 0.1% boron, 0.01 to 1% niobium, 0.01 to 1% zirconium, less than 110% iron, less than 1% tantalum, less than 1% hafnium and remainder cobalt. At least one of 0.01 to 1 wt% titanium and 0.01 to 1 wt% (combined amount) rare earth elements is added to the alloy. The alloy is used as a casting and contains eutectic carbides and secondary carbides precipitated substantially uniformly in the grains. If the secondary carbides are formed by an age-treatment conducted at a higher temperature than that at which the alloy is actually used, the high-temperature strength and the high-temperature ductility of the alloy are remarkably improved. The cobalt base alloy is formed into gas turbine nozzles by a precision casting.
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