Ti-Al coatings (=25, 33.3, 50, 66.7, and 75 at%) were fabricated in situ using high-frequency induction heating synthesis (HFIHCS). The process parameters for preparing Ti-Al coatings via HFIHCS were orthogonally optimized employing the finite element method. The effect of the aluminum content on the microstructures and phase compositions of Ti-Al coatings fabricated by HFIHCS, as well as their oxidation behaviors at 900℃ for 100 h was investigated. The results showed that the distribution of interfacial temperature difference was influenced by induced current (62.11%), relative density of compact (9.86%), and indenter material (28.03%). The minimum interfacial temperature difference was achieved with an induced current of 300 A, a graphite indenter material, and a compact density of 82.9%. The Ti-Al coatings exhibited a core (Ti)-shell (TiAl) ring structure. The rise in aluminum content in the Ti-Al coatings led to a gradual reduction in the titanium-rich phase, accompanied by a progressive increase in the aluminum-rich phase and the interface thickness of zones Ⅰ and Ⅱ. The porosities of Ti-Al coatings containing over 50 at% aluminum exhibited an order of magnitude higher than those of Ti-Al coatings with 50% aluminum or lower. The mechanisms of reaction, pore-forming, and interfacial diffusion for Ti-Al coatings were predominantly controlled by dissolution-precipitation, thermal expansion of intrinsic pores within the cold-pressed compact and voids formed after molten aluminum flow, and liquid-solid co-diffusion, respectively. The increase in aluminum content in the Ti-Al coatings led to in a gradual decrease in its oxidative weight gain, a shift in the oxidation kinetics from a linear-parabolic to a parabolic law, and an enhancement in preservation of internal core-shell characteristics and the likelihood of forming a protective layer of thin AlO. The oxidation behaviors of Ti-Al coatings with a core-shell structure were co-controlled by the aluminum content and the porosity affected by the aluminum content.

中文翻译：

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高频感应加热燃烧Ti-xAl涂层的原位合成及氧化行为

使用高频感应加热合成 (HFIHCS) 原位制造 Ti-Al 涂层（=25、33.3、50、66.7 和 75 at%）。采用有限元法对HFIHCS制备Ti-Al涂层的工艺参数进行正交优化。研究了铝含量对HFIHCS制备的Ti-Al涂层微观结构、相组成以及900℃、100 h氧化行为的影响。结果表明，界面温差分布受感应电流（62.11%）、压坯相对密度（9.86%）和压头材料（28.03%）的影响。最小界面温差是在感应电流为 300 A、石墨压头材料和压坯密度为 82.9% 时实现的。 Ti-Al涂层呈现出核(Ti)-壳(TiAl)环结构。 Ti-Al涂层中铝含量的增加导致富钛相逐渐减少，同时富铝相和Ⅰ区和Ⅱ区界面厚度逐渐增加。铝含量超过 50 at% 的 Ti-Al 涂层的孔隙率比铝含量为 50% 或更低的 Ti-Al 涂层高一个数量级。 Ti-Al 涂层的反应、成孔和界面扩散机制主要受溶解-沉淀、冷压坯内固有孔隙的热膨胀以及熔融铝流动后形成的空隙以及液-固共存的影响。分别为扩散。 Ti-Al涂层中铝含量的增加导致其氧化增重逐渐减少，氧化动力学从线性抛物线规律转变为抛物线规律，并增强了内部核壳特性的保存以及形成薄 Al2O 保护层的可能性。核壳结构Ti-Al涂层的氧化行为受铝含量和受铝含量影响的孔隙率共同控制。