The interfacial reactions between liquid Ti-48Al-2Cr-2Nb and various shell mold materials were investigated, and a cost-effective shell mold, containing a reacted component, was developed. Centrifugal investment casting was employed to supplement the low fluidity of the titanium aluminide alloy. The thickest part of the turbocharger was selected for analysis. The reaction-layer depth and the reacted product were evaluated using a micro-Vickers hardness tester and an electron microscope. The chemical composition and morphology of the molds were analyzed via X-ray diffraction and energy dispersive X-ray spectrometry. The TiAl alloys reacted with both colloidal silica and refractory materials in the alumina and zircon mold. However, only the colloidal silica reacted with TiAl in the yttria mold because of the high thermodynamic stability of the yttria refractory. The zircon mold showed the highest reactivity with TiAl because the zircon decomposed into ZrO 2 and SiO 2 at 1556 °C. The reactivity between TiAl and the mold decreased in the order of zircon > alumina > yttria ≥ rutile-containing alumina mold. The Ti 5 (Al, Si) 3 or (Ti, Zr) 5 (Si, Al) 3 phase was observed in the castings obtained using the conventional oxide mold. However, the reaction phase and layer were not observed in rutile-containing alumina mold. The molten TiAl penetrated the shell mold, especially in the colloidal silica site, although the penetration depth did not match the reaction-layer depth. The reaction and penetration of TiAl were controlled efficiently with the rutile-containing alumina mold.

中文翻译：

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Ti-48Al-2Cr-2Nb合金熔模铸造非反应性模具的研制

研究了液态 Ti-48Al-2Cr-2Nb 与各种壳模材料之间的界面反应，并开发了一种包含反应组分的具有成本效益的壳模。离心熔模铸造被用来补充钛铝合金的低流动性。选择涡轮增压器最厚的部分进行分析。使用显微维氏硬度计和电子显微镜评价反应层深度和反应产物。通过 X 射线衍射和能量色散 X 射线光谱法分析模具的化学成分和形貌。TiAl 合金在氧化铝和锆石模具中与胶体二氧化硅和耐火材料发生反应。然而，由于氧化钇耐火材料的高热力学稳定性，在氧化钇模具中只有胶体二氧化硅与 TiAl 反应。由于锆石在 1556 °C 分解为 ZrO 2 和 SiO 2 ，​​因此锆石模具与 TiAl 的反应性最高。TiAl与结晶器的反应活性以锆石>氧化铝>氧化钇≥含金红石型氧化铝结晶器的顺序降低。在使用常规氧化物模具获得的铸件中观察到Ti 5 (Al，Si) 3 或(Ti，Zr) 5 (Si，Al) 3 相。然而，在含金红石的氧化铝模具中没有观察到反应相和层。尽管渗透深度与反应层深度不匹配，但熔融的 TiAl 穿透了壳模，尤其是在胶体二氧化硅部位。