Two Ti-63.39Al-8.26Nb-0.2Y powders (powder 1 and powder 2) were fabricated by rapid in situ reaction and arc melting, respectively, then deposited on 316L stainless-steel substrate by the high-velocity oxygen fuel (HVOF) process. The phase composition, microstructure, porosity, microhardness, and adhesive strength of the two kinds of coating (DC1 and DC2) were characterized. DC1 had lower porosity, higher microhardness, and higher adhesive strength than DC2, which can be attributed to the difference in particle size distribution and mean particle size; a narrow particle size distribution and suitable mean particle size favor the formation of a HVOF coating with denser and more uniform microstructure. The thermal shock behavior was investigated by heating and water quenching from 600 °C to room temperature. The results showed that the failure of both TiAlNb coatings occurred due to spallation of the top coat, but the thermal shock resistance of DC2 was better than that of DC1. Thermal stress concentration caused by thermal expansion mismatch between the top coat and substrate was recognized as the major reason for TiAlNb coating failure.

中文翻译：

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超音速火焰喷涂 TiAlNb 涂层的特性和抗热震性

分别通过快速原位反应和电弧熔化制备两种 Ti-63.39Al-8.26Nb-0.2Y 粉末（粉末 1 和粉末 2），然后通过高速氧气燃料（HVOF）沉积在 316L 不锈钢基材上过程。表征了两种涂层（DC1和DC2）的相组成、微观结构、孔隙率、显微硬度和粘附强度。DC1比DC2具有更低的孔隙率、更高的显微硬度和更高的粘合强度，这可以归因于粒度分布和平均粒度的差异；窄的粒径分布和合适的平均粒径有利于形成具有更致密和更均匀微观结构的 HVOF 涂层。通过加热和水淬从 600 °C 到室温来研究热冲击行为。结果表明，两种 TiAlNb 涂层的失效都是由于面涂层的剥落，但 DC2 的抗热震性优于 DC1。由顶涂层和基材之间的热膨胀不匹配引起的热应力集中被认为是 TiAlNb 涂层失效的主要原因。