Mechanical Properties of Brazing Filler Alloys at Elevated Temperatures

Abstract

In using the brazed joint at high temperature, we have thought that the strength of brazed joints is related to the mechanical properties of brazing filler alloys at elevated temperatures. In this study, we adopted nine kinds of brazing filler alloy composed of Ag-P-Cu, Ag-Cu-Zn-Cd and Cu-Zn systems that were used for brazing copper and copper alloys, and tested their tensile strength, elongation and hardness in the range from the room temperature to 500°C.
The test results are summarized as follows;
1) Ag-P-Cu systems
With an increasing content of Ag, the mechanical properties at the room and elevated temperatures improved, and a filler alloy of 5%Ag is stronger than one of 15%Ag at the temperature under 250°C, but at over 250°C, the opposite is true.
2) Ag-Cu-Zu-Cd systems No definite relationship was found between Ag content and mechanical properties at elevated temperatures.
3) The mechanical properties of Ag-P-Cu systems are stronger than those of Ag-Cu-Zu-Cd systems at the temperature under 250°C but at over 250°C, the opposste is true.
4) The influences of work hardening on the strength of Ag-P-Cu systems are eliminated at 250°C, but on that of Ag-Cu-Zn-Cd systems they remain a little at 500°C.
The mechanical properties at elevated temperatures have been improved by work hardening and the effect of the latter is remarkable with an increasing Ag content.