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# Joining behaviour of crystalline and amorphous Zr-based alloy using Cu-based braze

Chiu, Yen-Lin (2014)
M.Phil. thesis, University of Birmingham.

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## Abstract

The objective of this research was to understand the melting and wetting behaviour of braze alloys and mechanical properties of brazed joints for pure zirconium plates and the Zr-based bulk metallic glass (BMG), Vitreloy 105 (Zr$$_5$$$$_2$$$$_.$$$$_5$$Cu$$_1$$$$_7$$.$$_9$$Ni$$_1$$$$_4$$$$_.$$$$_6$$Al$$_1$$$$_0$$Ti$$_5$$). Active brazing alloy, Cusil ABA (Ag$$_6$$$$_3$$Cu$$_3$$$$_5$$$$_.$$$$_2$$$$_3$$Ti$$_1$$$$_.$$$$_7$$$$_5$$), has been used to braze Zr plates in the Gleeble 3500 thermo- mechanical simulator under vacuum at 3 temperatures (840, 940 and 1000 $$^o$$C) and with Vitreloy105 at 780 $$^o$$C. The shear strength of the brazed Zr-plate increased at lower brazing temperatures; brazing of Vitreloy 105 plates was not successful as the brazing temperature, (Cusil ABA liquidus temperature) exceeded its crystallisation temperature Tx=440 $$^o$$C leading to crystallization and embrittlement during to brazing. As a result, three BMG compositions (Mg$$_6$$$$_5$$Cu$$_1$$$$_5$$Ag$$_1$$$$_0$$Tb$$_1$$$$_0$$$$_,$$Zn$$_4$$$$_0$$Mg$$_1$$$$_1$$Ca$$_3$$$$_1$$Yb$$_1$$$$_8$$ and Ca$$_6$$$$_5$$Mg$$_1$$$$_5$$Zn$$_2$$$$_0$$) as potential brazes for Vitreloy 105 with liquidus temperatures below the crystallisation temperature and high values of fracture strength have been selected to predict (using Thermo- Calc) the equilibrium reaction between substrate and braze prior to manufacture in order to estimate likely wettability and joint strength.

Type of Work: M.Phil. thesis. Strangwood, Martin Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Metallurgy and Materials TA Engineering (General). Civil engineering (General) University of Birmingham 4853
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