Abstract
Vacuum brazing of TiAl intermetallic alloy to Si3N4 ceramics was performed using Ag-28Cu (wt.%) filler alloy. The brazing joints obtained at different brazing temperatures were studied in this work. The microstructure and the shear strength were analyzed in detail. The results show that the brazed joints could be divided into three regions: AlCu2Ti reaction layer near the Ti-48Al-2Cr-2Nb alloy, a typical Ag-Cu eutectic structure and a thin continuous TiN + Ti5Si3 reaction layer near the Si3N4 ceramics. The microstructure varied as the brazing temperature was increased from 1153 K/15 min to 1193 K/15 min. The shear strength of the joints first increased as the brazing temperature increased from 1153 K to 1173 K, and then decreased. The maximum shear strength reached 105.5 MPa at 1173 K/15 min and the mechanism was discussed.
Highlights
In the last decades, TiAl alloys have received considerable attention due to its higher specific strength, lower density and excellent creep resistance at elevated temperatures, which can be used as potential candidates for high temperature structural applications [1,2,3,4]
It is well known that the filler metals play an important role in brazing ceramics to metals
The Ag-Cu filler alloy was sandwiched brazing seam was characterized by X-ray diffraction (XRD)
Summary
TiAl alloys have received considerable attention due to its higher specific strength, lower density and excellent creep resistance at elevated temperatures, which can be used as potential candidates for high temperature structural applications [1,2,3,4]. Researchers have studied the vacuum brazing of TiAl alloys to ceramics. Compared with transient liquid phase bonding, diffusion bonding, etc., vacuum brazing is advanced in simplicity, lower cost and high quality [15,16]. When used as wave-transparent materials in antenna radomes, it would be brazed to a TiAl intermetallics holder. It is well known that the filler metals play an important role in brazing ceramics to metals. Due to the low melting point and excellent wettability and ductility [21,22,23], the AgCu based filler alloy was effective in reducing the mismatch of the coefficients of thermal expansion. 8 in brazing Si3N4 ceramics to metals. An Ag-28Cu filler alloy was developed to braze the Si3N4 ceramics to a quality, such as the surface as chip resistors [20].brazed. The used microstructure of the jointsfor was characterized by X-ray the quality of the surface has rarely been studied
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