合金元素对典型阻燃钛合金燃烧行为的影响

Investigation on the effect of elements on the burning behavior of burn resistant titanium Alloys

摘要:

阻燃钛合金是飞机发动机核心部件中的重要材料，由于钛合金燃烧过程难以控制，燃烧参数难以获得加大了研究难度。论文以典型阻燃钛合金Ti40和Ti14为研究对象，利用高速摄影在不同氧分压环境下通过直流点火研究其燃烧行为，探索其燃烧过程中的氧扩散过程，明确合金元素对阻燃行为的影响 。研究发现两种合金燃烧后均形成分层结构，Ti40合金中Cr和V元素向外扩散，和氧反应生成Cr2O3/V2O5，密度高于TiO2的密度，Ti原子很难通过Cr2O3向外扩散与氧反应，提高燃烧表面致密度，抑制氧的扩散；而对于Ti14合金，共析反应生成大量的液相，富Cu相包裹Ti相球化晶粒形成Cu元素富集层，隔离氧并减少钛与氧的接触，从而降低氧向基体的扩散速率，同时Cu相的包裹作用增加氧扩散的距离，氧需要更多的能量扩散与Ti接触并反应，从而抑制了反应的发生。

Abstract:

To alleviate "titanium Fire" produced during high pressure and friction of titanium alloy, Ti-V-Cr series and Ti-Cu-Al series burn resistant titanium alloys have been developed. In this work, through a modified direct current simulation burning tests, the burning characteristics, e.g., flame height, velocity and burning products are measured to evaluate the burn resistant behavior. It shows the burning behavior and reveals the corresponding burning mechanisms of titanium alloys with different alloying elements. The formation of V2O5 and Cr2O3 oxides during burning of Ti40 alloy enhances the density of oxide layer to block the oxygen diffusion, which leads to excellent burn resistant behavior indicated by the smaller burning velocity and lower flame height. For Ti14 alloys, in comparison, a clear Cu-rich layer is formed at the interface between burning product and heat affected zone, where it consumes oxygen by produces Cu-O compounds and to reduces the burning reaction with Ti-matrix. This work has established a fundamental understanding of how the alloying elements improve the burning resistance of titanium alloys.