For lightweight constructions, joining dissimilar metals is often indispensable to achieve exceptional properties. A common challenge is the bonding of steel and aluminum parts. The use of cold-sprayed coatings as a bonding agent is an innovative approach for high pressure die casting (HPDC) aluminum-steel hybrid components in order to achieve a metallurgical bonding, although it comes with high requirements in terms of coating adhesive and cohesive strength. Therefore, the main aim of this study is the optimization of a post-processing treatment of cold-sprayed coatings in order to improve the cohesive strength to help the introduced coatings withstand the mechanical and thermal stresses during HPDC. The effect of the heat treatment on the mechanical properties of the cold-sprayed Al99.0 and AA7075 coatings was investigated. Freestanding coatings were heat-treated at a temperature of T = 400 °C for different dwell times in order to analyze the recrystallization kinetics through hardness measurements. Two different heat treatment states along with an as-sprayed condition were chosen to investigate the evolution of the mechanical properties of the coatings by means of 3-point bending tests. Besides the softening of the coatings during the heat treatment, sintering effects at splat boundaries and their impact on fracture mechanisms were investigated using electron microscopy.

中文翻译：

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冷喷涂铝基涂层 AA1200 和 AA7075 在退火过程中的软化行为

对于轻质结构，连接异种金属通常是实现卓越性能必不可少的。一个常见的挑战是钢和铝部件的粘合。使用冷喷涂涂层作为粘合剂是高压压铸 (HPDC) 铝-钢混合组件实现冶金结合的一种创新方法，尽管它在涂层粘合性和内聚强度方面有很高的要求. 因此，本研究的主要目的是优化冷喷涂涂层的后处理处理，以提高内聚强度，帮助引入的涂层在 HPDC 期间承受机械和热应力。研究了热处理对冷喷涂 Al99.0 和 AA7075 涂层机械性能的影响。独立涂层在 T = 400 °C 的温度下热处理不同的停留时间，以便通过硬度测量分析再结晶动力学。选择两种不同的热处理状态以及喷涂状态，通过 3 点弯曲试验研究涂层机械性能的演变。除了在热处理过程中涂层软化外，还使用电子显微镜研究了板状边界处的烧结效应及其对断裂机制的影响。选择两种不同的热处理状态以及喷涂状态，通过 3 点弯曲试验研究涂层机械性能的演变。除了在热处理过程中涂层软化外，还使用电子显微镜研究了板状边界处的烧结效应及其对断裂机制的影响。选择两种不同的热处理状态以及喷涂状态，通过 3 点弯曲试验研究涂层机械性能的演变。除了在热处理过程中涂层软化外，还使用电子显微镜研究了板状边界处的烧结效应及其对断裂机制的影响。