Abstract
The influences of Li content on the corrosion behavior of TC4 (Ti6Al4V) titanium alloy were explored when the TC4 titanium alloy was immersed in Al–Li alloy melt containing 0%, 1%, and 2% lithium at 680 °C, 700 °C, and 720 °C for 0.5 h, 1 h, and 2 h. The structure and growth law of the diffusion reaction layer at solid–liquid interface were studied, and the growth kinetic equation of the diffusion reaction layer was established. In addition, Ti content in Al–Li alloy melt was determined and its dissolution rate was calculated. The results showed that with the increase of lithium content in the melt, the thickness of the diffusion reaction layer (DRL) between TC4 titanium alloy and the melt increased significantly, and the activation energies of the diffusion reaction obtained were 141.28 kJ·mol−1 in liquid Al, 86.62 kJ·mol−1 in liquid Al–1Li alloy, and 43.42 kJ·mol−1 in liquid Al–2Li alloy, respectively. The dissolution rate of Ti in Al–Li alloy melts increased with the increase of lithium content in melts. When the holding time reached 3 h in a TC4 crucible, the content of Ti dissolved in the Al–2Li alloy melt was 0.105 wt%.
Highlights
In recent years, with the increasing development of the aviation industry, the research and development of related materials have entered a new stage
It can be observed from the EDS line scanning result in Figure 2b that the closer to the TC4 titanium alloy side, the lower the Al content is in diffusion reaction layer (DRL), which indicates that the Ti element was continuously dissolved by the melt and the Al element was continuously diffused to DRL
Some protrusions formed at the interface between DRL and the TC4 titanium alloy
Summary
With the increasing development of the aviation industry, the research and development of related materials have entered a new stage. The high-temperature molten aluminum alloys have strong chemical activity and corrosion ability, and it is easy to destroy the purity of the melt by dissolving the elements such as iron and nickel in the container and taking them into the melt [6] In casting, these harmful elements will be introduced into aluminum alloy ingot, forming various thick phases Fe-containing or Ni-containing in the matrix [7,8], which will have a strong splitting effect on the matrix, decreasing the mechanical properties of the alloy, especially plasticity [9,10]. When a certain amount of titanium dissolved in melt, it can be used as the grain refiner of aluminum alloy to refine the grain size and improve the formability and mechanical properties of final products [14] It is of great theoretical and practical value to study the corrosion behavior of titanium alloy in aluminum–lithium alloy melt. The study will provide the experimental basis for the optimization of the aluminum–lithium alloy smelting process and equipment up-gradation
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