Al基合金の超高圧力溶融実験における不純物の混入防止と融点検出の技術(<特集>高圧力 : 固体の高圧物性, 反応, 実験技術)

概要

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High-pressure treatment was carried out for Al-based alloys in the range of room temperature to 1300℃. The pressure was applied up to 7GPa by using a cubic-anvil device. A cylindrical bulk sample was placed into a boron nitride capsule and inserted into a carbon tube heater. Metal disks were attached on the top and bottom of the heater for the electrical contact with an external power supplier. Pyrophyllite was used as a pressure medium to attain quasihydrostatic condition. (1) A large amount of impurity was introduced into the specimen from the metal disk when the specimen was molten. Such a trouble never occurred if the specimen was kept solid during the treatment. Since a few small cracks were inevitably produced in the capsule and the heater by pressing, the encapsuled liquid metal oozed from the capsule through them, reached the disk and reacted. Such contamination was avoidable when disks made of graphite was used. (2) The electric conductivity of the heater altered when the liquid metal exuded and contacted the heater. The corresponding signal can be sensitively detected by monitoring the voltage and current of heater when elevating temperature, indicating the emergence of liquid phase. It was applicable as the easy measurement of specific temperature in fusion-related phenomena such as melting and eutectic reaction.
1998-10-15