Effect of P Content on the Microstructure and Mechanical Properties of Cu-P-Sn-Ag Quaternary Alloy Solder.

Cu-P-Sn-Ag quaternary alloy brazing material is prone to brittle fracture of wire during industrial production, which seriously affects product quality. To improve its mechanical properties, Cu-P-Sn-Ag quaternary alloy ingots and brazing materials with different P contents were prepared. The effects of P content on the microstructure, hardness, tensile strength, and elongation of the brazing material were systematically studied. The results show that when the P content is between 5.0% and 5.2%, the brittle phase Cu₃ P structure in the alloy is small and short rod-shaped, with grain size less than 5 µm. When the P content is between 5.4% and 6.0%, some Cu₃ P structures in the alloy gradually transform into coarse fishbone like structures, with grain sizes greater than 30 µm. When the P content ranges from 5.2% to 5.4%, the hardness of the solder increases significantly with the increase of P content, from 247.7 HV to 260.4 HV; Its tensile strength and elongation significantly decreased from 844.38 MPa and 3.60% to 815.08 MPa and 3.07% respectively. The evolution relationship between P content and microstructure is the main factor affecting the mechanical properties of brazing materials. [ABSTRACT FROM AUTHOR]