Ternary Cu-Zn-In and quaternary Cu-Zn-In-Ga alloy systems were studied to select compositions suitable as brazing filler metals. The selected alloys had liquidus temperature in the range of 1040-1150 K (1410-1610^oF), and brazing filler metals prepared from these alloys had brazing temperatures below 1183 K (<1670^oF).

  The developed brazing filler metals exhibited tensile strength in the range of 498-656 MPa (72-95 ksi) in the initial state at the relative elongation not less than 18%, and yield strength 380-510 MPa (55-74 ksi).  High plasticity provides easy processing of the initial cast bars into wire and strips by rolling and pressing.

   The surface tension of molten brazing filler metals was from 0.9 mJ to 1.1 mJ at brazing temperature.  All filler metals possessed good fluidity on copper, stainless steel, ceramics, and some composite materials. The spreading area of standard  filler metal samples  was measured in the range of (650 – 929) ·10^-5 m². The coefficient of filling of vertical gap was not less than 80%.

    Strength of brazed joints made using Cu-Zn-In and Cu-Zn-In-Ga filler metals depends on the width of initial joint clearance. The standard brazed specimens of brass, which were assembled with the joint clearance of 80-100 microns, were broken  by a base metal only at 360 MPa (52 ksi). The impact strength of standard brass brazed specimens was in the range of 9.3–10.6 kg/cm².  The same specimens having the width of joint clearance as big as 300 microns showed the tensile strength of 320 MPa (46.4 ksi) and impact strength only 3.6 kg/cm².  Other base metals brazed with these filler metals exhibited similar mechanical behavior.

 These brazing filler metals were manufactured in amount of 1.5 tons and were used as substitutes for silver-based filler metals for brazing parts of 200 MW electric generators with hydrogen cooling.