Effect of plasma surface metallizing Nb on diffusion welding performance of γ-TiAl alloy

doi:10.13251/j.issn.0254-6051.2022.02.038

Abstract

Abstract: Double glow plasma metallizing technology was used to prepare Nb coating on the surface of γ-TiAl alloy with a nominal composition of Ti-45Al-8.5Nb (W, B, Y). Effect of Nb depositing temperature and welding temperature on microstructure and properties of the γ-TiAl alloy diffusion welded joints was studied by SEM, EDS, XRD, etc. The results show that dense Nb coating can be formed on the γ-TiAl alloy at the Nb depositing temperature range of 800-950 ℃. The grain size and roughness of the Nb coating increase continuously with the increase of Nb depositing temperature. The typical joint structure from the substrate to welded center can be divided into 4 layers: layer I (diffusion layer between substrate and Nb coating), layer II (Ti-Nb miscible layer containing small amount of AlNb₂), layer III (Ti-riched TiNi layer), layer IV (near equiatomic TiNi layer). The shear strength of the joint increases first and then decreases with the increase of Nb depositing temperature and welding temperature. The joint prepared at Nb depositing temperature of 850 ℃ and diffusion welding temperature of 900 ℃ achieves the highest shear strength, up to 82.0 MPa.

Key words: TiAl alloy, double glow plasma metallizing technology, Nb coating, diffusion welding

CLC Number:

TG441.3

Sun Dingbang, Wang Yongsheng, Gao Jie, He Zhiyong, Wu Yanxia, Zhou Bing, Ma Yong, Yu Shengwang. Effect of plasma surface metallizing Nb on diffusion welding performance of γ-TiAl alloy[J]. Heat Treatment of Metals, 2022, 47(2): 213-218.

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