Rapid solidification and metastable phase formation during surface modifications of composite Al-Cr cathodes exposed to cathodic arc plasma

• 作者: Mehran Golizadeh Francisca Mendez Martin Stefan Wurster Johann P.Mogeritsch Abdellah Kharicha Szilard Kolozsvári Christian Mitterer Robert Franz
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（35）
• 页码范围: 147-163
• 页数: 17页
• 语种: 英文

摘要

A combination of both conventional and advanced high-resolution characterization techniques was ap-plied to study the modified layers on the surface of three composite Al-Cr arc cathodes with identical nominal composition of Al-50 at.％ Cr but varying powder grain sizes.The results revealed that the mod-ified layers consist mainly of metastable phases such as Cr solid solution,high temperature cubic Al8Cr5,supersaturated Al solid solution,and icosahedral quasicrystal.The metastable phase formation indicates that high cooling rates were involved during the solidification of molten material produced in the arc craters during cathode spot events.The average cooling rate was estimated to be 106 K/s based on sec-ondary dendrite arm spacing measurements and supporting phase-field based simulations.The formation mechanisms of the modified layers are discussed based on the obtained results and the current literature.