ZrTiAlV alloy grain refining under high-pressure torsion and electric field-assisted heat treatment

摘要

To reduce grain size, shorten heat treatment time, and guarantee good comprehensive mechanical properties of ZrTiAlV alloy, we proposed a grain refining technology, which is a combination of electric field-assisted heat treatment and high-pressure torsion. And using this technology we studied ZrTiAlV alloy grain refining. The original material consists of pure phase a, which will be changed into pure phase beta at temperatures exceeding 700 degrees C during electric field-assisted heat treatment. The temperature required for the phase a of the high-pressure torsion material to be completely changed into phase beta increases obviously. When the torsion pressure is 5 GPa, the initial heat treatment temperature is higher than 700 degrees C and the final heat treatment temperature reaches 800 degrees C, only then can the phase a be completely changed into a phase beta structure. When the initial heat treatment temperature is higher than 600 degrees C, the large grains of phase contain a large amount of sub-grain boundaries, and the sub-grains are smaller than 100 mu m. When the initial temperature is 700 degrees C, the grains are completely refined and re-crystallization is quite complete. The difference in the orientation angle of the large and small grains is small, indicating continuous dynamic re-crystallization. The original material consists mainly of lath-shape phase a structure; after high-pressure torsion at 4 GPa and electric field-assisted heat treatment at 800 degrees C, the phase structure becomes nearly pure and only a few minor a phase structures are created. (C) 2017 Published by Elsevier Inc.