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

Chiu, Yen-Lin (2014). Joining behaviour of crystalline and amorphous Zr-based alloy using Cu-based braze. University of Birmingham. M.Phil.

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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:

Thesis (Masters by Research > M.Phil.)

Award Type:

Masters by Research > M.Phil.

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