Effect of ZrO₂ Nanomaterials on Wettability and Interfacial Characteristics of Al-19Cu-11Si-2Sn Filler Metal for Low Temperature Al to Cu Dissimilar Brazing.

Dissimilar Al 3003 and Cu tubular components were successfully brazed without interface cracking using ZrO₂ nanomaterials reinforced with Al-19Cu-11Si-2Sn filler. The filler was initially cast using an induction furnace and processed into ring form for brazing. Al-19Cu-11Si-2Sn filler with coarse CuAl₂ and Si phases (43 and 20 μm) were refined to 8 and 4 μm, respectively, after the addition of 0.1 wt. % ZrO₂ and shows significant improvement in the mechanical properties. ZrO₂ nanomaterials' induced diffusion controlled growth mechanism is found be the responsible for the refinement of CuAl₂ intermetallic and Si particles. The wettability of Al-19Cu-11Si-2Sn-0.1ZrO₂ increased to 78.17% on Cu side and 93.19% on the Al side compared from 74.8% and 89.9%, respectively. Increase in the yield strength, ultimate tensile strength, and percentage elongation were noted for the brazed joints. Microstructure of induction brazed joint with 40 kW for 6 seconds using Al-19Cu-11Si-2Sn-0.1ZrO₂ filler shows thin interfacial CuAl₂ intermetallic compound along the copper side and inter-diffusion region along the aluminum side and their respective mechanism is discussed. The tensile strength of the joints increased with increasing the nanomaterials addition and shows a base metal fracture. Analysis of fractured samples shows the effectiveness of ZrO₂ reinforced filler in crack propagation through the filler.