To improve the working accuracy of a sheet material by coating the face of an Ni3Al sheet material to be worked with a baron diffusing agent and executing diffusing treatment.
The face of a sheet material composed of Ni3Al to be worked is coated with a boron diffusing agent. It is applied to at least either the front side or rear side in the face to be worked. As the boron diffusing agent to be applied, a general high temp. diffusing agent for semiconductors can be used. After the application, boron diffusing treatment by heat is executed. In this boron diffusing treatment, boron is cemented only into the surface layer at the inside of the sheet material. As for the heat treating conditions, generally, heat treatment at 700 to 1100°C for about 30 to 120min shall be executed. The heat treatment is executed preferably in an inert gaseous atmosphere of gaseous nitrogen or the like. This invension is excellent in dimensional accuracy. Thus, the generation of cracking, sagging and burrs at the time of punching can be suppressed.
SUDOU SETSUKO
SANO TOSHIO
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