Protective coatings based on an Al-Al2O3 metal matrix composite (MMC) were sprayed using dynamic metallization (DM), a low-pressure cold spray variant. A series of samples approximately 1 mm in thickness were sprayed using different spray process parameters (temperature, velocity) and different feedstock powder compositions (Al, Zn, Al2O3). This resulted in MMCs of different phase compositions and slightly different physical conditions of coating formation. The through-thickness residual stresses that accumulate in coatings during the spray process were studied using neutron diffraction in all phases comprising the MMCs. The overall residual stress in the coating (macrostress) was compressive, which is in good agreement with the data on residual stress observed in other cold spray coatings, accumulating as a result of the peening process. However, due to the slightly elevated spray temperature characteristic of DM in comparison with other cold spray variants, thermal stresses are also present and play an equally important role in the accumulation of residual stress in each phase. Because of the multi-phase composition and thermal mismatch between the metal and ceramic components of the MMC, inter-phase microstresses also accumulate. A micro-mechanical explanation of the observed tensile microstress in Al/Zn versus compressive stress in Al2O3 is proposed.

中文翻译：

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冷喷涂（动态金属化）Al-Al2O3基腐蚀防护涂层宏观应力和微观应力的中子衍射研究

基于 Al-Al2O3 金属基复合材料 (MMC) 的保护涂层采用动态金属化 (DM)（一种低压冷喷涂变体）进行喷涂。使用不同的喷涂工艺参数（温度、速度）和不同的原料粉末成分（Al、Zn、Al2O3）喷涂一系列厚度约为 1 mm 的样品。这导致MMC具有不同的相组成和涂层形成的物理条件略有不同。使用中子衍射研究了喷涂过程中涂层中积累的全厚度残余应力，包括MMC 的所有相。涂层中的总体残余应力（宏观应力）是压缩的，这与在其他冷喷涂涂层中观察到的残余应力数据非常一致，由于喷丸过程而累积。然而，由于与其他冷喷涂变体相比，DM 的喷涂温度特性略有升高，因此也存在热应力，并且在各相残余应力的积累中发挥着同样重要的作用。由于MMC 的金属和陶瓷成分之间的多相成分和热失配，相间微应力也会累积。提出了对观察到的 Al/Zn 中的拉伸微应力与 Al2O3 中的压缩应力的微观机械解释。