TiAl alloys, with half the density of nickel-based superalloys, are highly suitable for aerospace applications requiring lightweight materials. However, they tend to form a nonprotective mixed oxide film on their surface at high temperatures. This oxide film is prone to cracking, which can lead to long-term high-temperature oxidation surface degradation, thereby reducing their high-temperature creep and fatigue resistance. Surface cracks on the oxide film further aggravated the brittleness of the TiAl intermetallic compounds after high-temperature exposure. While coatings are typically applied to promote the formation of dense oxides for surface protection, they primarily enhance oxidation resistance. However, this improvement comes at the cost of reducing the high-temperature creep and fatigue resistance and the room-temperature plasticity of TiAl alloys. This study introduced an electroless coating method to deposit a Pt coating, approximately 200 nm thick, on the surface of TiAl alloys. During high-temperature applications, the Pt dispersed as nanoparticles within the oxide layer, enhancing the oxide's plasticity. This oxide structure considerably improved the high-temperature creep and fatigue properties of TiAl alloys, while enhancing their room-temperature tensile properties after oxidation. This approach offers a novel strategy for designing surface coatings for high-temperature components.

中文翻译：

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一种提高 TiAl 合金综合高温服役性能的新型涂层方法


TiAl 合金的密度是镍基高温合金的一半，非常适合需要轻质材料的航空航天应用。然而，在高温下，它们往往会在其表面形成一层无保护性的混合氧化膜。这种氧化膜容易开裂，从而导致长期高温氧化表面降解，从而降低其高温蠕变和抗疲劳性。氧化膜上的表面裂纹进一步加剧了 TiAl 金属间化合物在高温暴露后的脆性。虽然涂层通常用于促进致密氧化物的形成以保护表面，但它们主要增强抗氧化性。然而，这种改进是以降低 TiAl 合金的高温抗蠕变性和抗疲劳性以及室温塑性为代价的。本研究介绍了一种化学镀层方法，在 TiAl 合金表面沉积约 200 nm 厚的 Pt 涂层。在高温应用中，Pt 以纳米颗粒的形式分散在氧化层内，增强了氧化物的可塑性。这种氧化物结构大大改善了 TiAl 合金的高温蠕变和疲劳性能，同时增强了其氧化后的室温拉伸性能。这种方法为设计高温部件的表面涂层提供了一种新颖的策略。