Joining of Alumina to Copper Using Amorphous Cu-Ti Filler Metal(Materials, Metallurgy & Weldability)

Abstract

Joining of alumina (99.62mass% Al2O3) to copper was made using amorphous Cu-Ti (34-57 at%) brazing filler metals at 1173 to 1323 K in 2.7•~10-3 Pa. The amorphous filler metals, 1 cm in width and 45 ,um thick, were produced by liquid quenching. The superior flexibility of amorphous filler provides simplicity to joining process. The fracture shear strength of the joints was measured at room temperature. The strength of the joints brazed at 1323 K for 1.8 ks using CusoTiso filler possesses 138.3 M Pa at room temperature. The strength of the joints at constant brazing time raises with an increase in brazing temperature. The strength increases slightly with an increase in titanium content in the filler. At 1298 K for 1.8 ks, the strength of joints at room temperature changes from 107.8 M Pa with Cu66Ti34 to 120.6 M Pa with Cu43Tis7. The strength of the joints was also investigated at high temperatures up to 973 K. The high temperature shear strength is almost constant up to 773 K, and deceases gradually at higher temperature. Isothermal solidification process takes place during joining, and copper dissoves into Cu-Ti filler metal, and then, copper solid solution containing Ti precipitates from Cu-Ti filler metal. On the other hand, the formation of titanium oxide TiO1 and (Al, Ti)2O3 solid solution oxide is attributable to the strong joining between alumina and Cu-Ti filler.