Interfacial Microstructure and Mechanical Properties of Zr/CoCrFeMnNi HEA Brazed Joints

Abstract:

AgCu filler was used to braze Zr and CoCrFeMnNi high-entropy alloy (HEA). The effects of brazing temperature and holding time on the microstructure and mechanical properties of the joints were analyzed. The results show that the typical microstructure of the joints brazed at 850 ℃ for 10 min is HEA/Cr_ss/Zr(Cr,Mn)₂/Zr₂(Co,Cu,Ni,Fe)+Zr₂(Ag,Cu)+Zr(Cr,Mn)₂/Zr. The joints have the maximum shear strength of 103.1 MPa. As the brazing temperature or holding time rises, the thickness of Cr-rich solid solution and Zr(Cr,Mn)₂ layer are increased, the content of Zr₂(Co,Cu,Ni,Fe) and Zr(Cr,Mn)₂ phase is increased whereas the content of Zr₂(Ag,Cu) phase is decreased. Finally, the failure mechanism of the joint was analyzed. Under the action of shear force, as the brazing temperature or holding time rises, the fracture position of the joint shifts from the Zr(Cr, Mn)₂ layer to the Zr₂(Co, Cu, Ni, Fe) phase fracture in the center of the brazing seam.