Interaction behaviors at the interface between liquid Al–Si and solid Ti–6Al–4V in ultrasonic-assisted brazing in air

Abstract

Power ultrasonic vibration (20 kHz, 6 μm) was applied to assist the interaction between a liquid Al-Si alloy and solid Ti-6Al-4V substrate in air. The interaction behaviors, including breakage of the oxide film on the Ti-6Al-4V surface, chemical dissolution of solid Ti-6Al-4V, and interfacial chemical reactions, were investigated. Experimental results showed that numerous 2-20 μm diameter-sized pits formed on the Ti-6Al-4V surface. Propagation of ultrasonic waves in the liquid Al-Si alloy resulted in ultrasonic cavitation. When this cavitation occurred at or near the liquid/solid interface, many complex effects were generated at the small zones during the bubble implosion, including micro-jets, hot spots, and acoustic streaming. The breakage behavior of oxide films on the solid Ti-6Al-4V substrate, excessive chemical dissolution of solid Ti-6Al-4V into liquid Al-Si, abnormal interfacial chemical reactions at the interface, and phase transformation between the intermetallic compounds could be wholly ascribed to these ultrasonic effects. An effective bond between Al-Si and Ti-6Al-4V can be produced by ultrasonic-assisted brazing in air.

Low‐Temperature Brazing of Titanium Using Al‐Based Filler Alloys

“…Using USV for a short period results in very fast destroying of the oxide layer on the parent material and wetting it by the filler material [52], even it is effective in achieving a good wetting on ceramics by the filler materials in the air [53,54,62]. e acoustic cavitation generated in the liquid metal is considered as the most important physical effect of the ultrasonic oscillation propagation [63][64][65][66].…”

“…e advantages include less specific atmosphere requirements due to the fast-breaking of the oxide layer [39,52], enhanced spreading of the molten filler [55,62], and homogenizing the microstructures of the joint [39]. Table 3 summarizes the technological parameters and the shear strength results of the ultrasound-assisted brazing of Ti/Ti and Ti/Al joints using Al-based fillers.…”

“…Chen et al [52] explored the instantaneous breakage behavior of the oxide film of Ti-6Al-4V on its interface with the liquid Al-Si alloy and the chemical interactions during the process using 20 kHz frequency and 5.5-7 μm amplitude USV. e samples were heated to 620°C then the titanium sonotrode was quickly loaded on the titanium substrate with a constant pressure of 0.2 MPa.…”

“…Using USV in brazing is an attractive assisting tool [37][38][39][52][53][54][55][56][57][58]; however, studying the combined effects of USV with the technological parameters of brazing process and developing a joint interface more compatible with the USV have not yet received an adequate attention. e focus in this review will be on the titanium/aluminum interface which includes Albased filler alloys for brazing titanium/titanium and titanium/aluminum parent (base) components, taking into consideration the technological parameters and procedures.…”

Effect of Si on Ti/Al brittle interfacial phases and microstructural evolution of pulsed current gas tungsten arc welding joints

“…Previous research works on the joining of Ti/Al have been reported [3,4,[7][8][9]. Some conventional fusion welding methods are not suitable for joining Ti/Al.…”