Microstructural evolution mechanisms of Ti600 and Ni-25%Si joint brazed with Ti-Zr-Ni-Cu amorphous filler foil

A commercial Ti-Zr-Ni-Cu amorphous filler foil was applied to braze the high-temperature Ti600 and Ni-25at%Si, resulting in the good joint between both of alloys. The interfacial microstructure of Ti600/Ti-Zr-Ni-Cu/Ni-25at%Si brazed joint at 1213 K for 10 min is mainly comprised of the continuous Ti2Ni phase. Most of Ti-rich phases such as alpha-Ti, (Ti,Zr)(2)(Ni,Cu) and (Ti,Zr)(2)Si formed in the vicinity of the Ti600 substrate except that Ti5Si3 precipitates near the Ni-25at%Si region, resulting in the formation of six distinct layers. The corresponding formation mechanism were clarified. The Ti5Si3 and Ni-31 Site were firstly formed during the initial stage followed by diffusion reactions at Ni-25at%Si side. The continuous Ti2Ni phase formed through the reaction of Ti(L) +Ni(L) Ti2Ni. a-Ti, Ti3Al, (Ti,Zr)(2)(Ni,Cu) and (Ti,Zr)(2)Si in the brazing joint precipitated through a solid-solid phase transformation. (C) 2016 Elsevier B.V. All rights reserved.