| 摘要 |
PROBLEM TO BE SOLVED: To increase the number of optical disks capable of being injection molded by a piece of molding stamper by producing a molding stamper with an Ni base alloy contg. a specified ratio of Al. SOLUTION: This stamper is produced by an Ni base alloy contg., be weight, 2.5 to 8.0% Al, and the balance Ni with inevitable impurities. The use of an Ni base alloy added with 0.10 to 5.0% Ti is also preferable. The molten metal obtd. by melting an Ni base alloy in a vacuum is cast into a mold and is cast into an ingot, e.g. of 300 mm height, 200 mm width and 2,000 mm length. The ingot is subjected to solution heat treatment at 1,100 deg.C for 5 hr, is thereafter hot-forget at 950 deg.C, is hot-rolled at 900 deg.C and is moreover cold-rolled at ordinary temp. to form into an Ni base alloy sheet material of 1 mm thickness. The Ni base alloy sheet material is held at 920 deg.C for 20 min, is subjected to annealing treatment under water cooling, is held at 590 deg.C for 16 hr, is thereafter cooled in a furnace at 8 deg.C/h, is subjected to heat aging treatment at 480 deg.C for 5 hr, is subsequently cut into a disk of 150 mm and is polished to obtain a substrate for a stamper.
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