Appeal No. 1997-0538
Application No. 08/262,168
20,000 to about 30,000 pounds per square inch, for a duration
of from about 1 to about 20 hours; and
heat treating the piece at a temperature of from about 5F
to about 300F below the alpha transus temperature for a time
sufficient to refine the microstructure and generate a
microstructure comprising from about 10 to about 90 volume
percent gamma phase, the step of heat treating being conducted
at a temperature of from about 45F to about 200F above the
temperature of the step of hot isostatic pressing.
14. A method of producing a gamma titanium aluminide alloy
article, comprising the steps of:
providing a piece of a gamma titanium aluminide alloy
having a composition capable of forming alpha, alpha-2, and
gamma phases;
determining the alpha transus temperature of the gamma
titanium aluminide alloy piece;
hot isostatic pressing the gamma titanium aluminide alloy
piece at a temperature of from about 125F to about 225F below
the alpha transus temperature and at a pressure of from about
20,000 to about 25,000 pounds per square inch, for a duration
of from about 2 to about 8 hours; and
heat treating the piece at a temperature of from about
50F to about 100F below the alpha transus temperature for a
time sufficient to refine the microstructure and generate a
microstructure comprising from about 20 to about 80 volume
percent gamma phase, the step of heat treating being conducted
at a temperature of from about 50F to about 100F above the
temperature of the step of hot isostatic pressing.
In support of his rejections, the examiner relies on the
following prior art:
Kim et al. (Kim) 5,226,985 Jul. 13,
1993
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