Multi-element Ti-based medium-entropy alloy brazing filler metal and application and brazing method of multi-element Ti-based medium-entropy alloy brazing filler metal

The invention relates to the technical field of aviation brazing, and provides a multi-element Ti-based medium-entropy alloy brazing filler metal which comprises the following components in percentage by weight: 16.0 to 22.0 percent of Mn, 12.0 to 18.0 percent of Fe, 2.0 to 8.0 percent of Ni, 2.0 to 8.0 percent of Co, 1.0 to 7.0 percent of V, 0 to 6.0 percent of Cr and the balance of Ti. The invention further provides application of the medium-entropy alloy brazing filler metal and a TiAl alloy brazing method. According to the brazing filler metal provided by the invention, TiAl can be brazed at the temperature of 1180-1190 DEG C, the room-temperature tensile strength of a brazed joint reaches 479-508 MPa, and the strength coefficient is 0.81-0.86; the tensile strength at 700 DEG C reaches 514-524 MPa, the tensile strength at 750 DEG C reaches 495-521 MPa, the tensile strength at 850 DEG C reaches 396-418 MPa, and the strength coefficient within the wide range of 700-850 DEG C is basically stabilized to be 0.