Microstructure and properties of gas shielded brazed joints of Ti60 titanium alloy

Gas shielded brazing of Ti60 titanium alloy was achieved by Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅ amorphous brazing filler metal. Distribution of alloy elements in brazed joints and effect of brazing parameters on microstructure and mechanical properties of brazed joints were investigated by means of scanning electron microscopy, energy dispersive spectroscopy, microhardness tester and electronic universal testing machine. Effect of change of brazing temperature and holding time on crystallization of brazed joints was analyzed. The results showed that Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅ amorphous brazing filler metal can be used to braze Ti60 alloy. Under the condition of 1 020 ℃ brazing temperature and 30 min holding time, Ti-Cu intermetallic compounds Ti₂Cu and a few (Ti,Zr)₂Cu intermetallic compounds were found in brazed joints. With the increase of brazing temperature or the prolongation of holding time, elements in brazed joints became more and more reactive. Ti element and Zr element in base metal on both sides and brazing filler metal were diffused with each other, and microstructure in brazed joints gradually grew and filled brazing seam, and tensile strength of brazed joints first increased and then decreased. When brazing temperature was 1 020 ℃ and holding time was 30 min, the maximum tensile strength of brazed joints was 529.6 MPa.