Low-Temperature Interface Reaction between Titanium and the Eutectic Silver-Copper Brazing Alloy

J. Andrieux (1) , Olivier Dezellus (1) , F. Bosselet (1) , J.C. Viala (1)

1 LMI - Laboratoire des Multimatériaux et Interfaces

Reaction zones formed at 790 °C between solid titanium and liquid Ag-Cu eutectic alloys (pure and Ti-saturated) have been characterized. When pure Ag-Cu eutectic alloy with 40 at.% Cu is used, the interface reaction layer sequence is: alpha-Ti / Ti2Cu / TiCu / Ti3Cu4 / TiCu4 / L. Because of the fast dissolution rate of Ti in the alloy, the reaction zone remains very thin (3-6 µm) whatever the reaction time. When the Ag-Cu eutectic alloy is saturated in titanium, dissolution no longer proceeds and a thicker reaction zone with a more complex layer sequence grows as the reaction time increases. Four elementary chemical interaction processes have been identified in addition to Ti dissolution in the liquid alloy. These are growth of reaction layers on Ti by solid state diffusion, nucleation and growth from the liquid of TiCu4, isothermal solidification of silver and, finally, chemical conversion of the Cu-Ti compounds by reaction-diffusion in the solid state. A mechanism combining these processes is proposed to account for the constitution of Ti/ Ag-Cu/ Ti joints brazed at 780-800 °C.

Mots clés: ternary system; metals; intermetallics; diffusion paths; chemical potential gradients

Domaines: Matériaux

J. Andrieux, Olivier Dezellus, F. Bosselet, J.C. Viala. Low-Temperature Interface Reaction between Titanium and the Eutectic Silver-Copper Brazing Alloy. Journal of Phase Equilibria and Diffusion, 2009, 30 (1), pp.40-45. ⟨10.1007/s11669-008-9424-7⟩. ⟨hal-00422608⟩