Composite peening - a novel processing technique for graded reinforced aluminiummatrix composites

陶瓷颗粒增强梯度复合材料在轻量化、耐磨和循环载荷结构部件方面具有很高的应用潜力。特别是使用陶瓷增强颗粒可以实现高热稳定性的表面硬化机制。目前，在高应力区域进行表面强化以改善机械性能的经济有效的制造工艺尚不存在。在微丸强化工艺的基础上，提出了一种新型的零件近表面强化技术，该技术允许有定义的分散体插入，称为复合强化。针对该强化工艺，采用改进的微喷丸强化工艺应使用对纯铝、AlSi12Mg和AlSiMg合金进行了温度、喷射压力、工作距离和喷丸剂直径等工艺相关变量的分析。同样，进一步改善机械性能的后处理程序也应加以调整和评估。制造材料状态的表征代表了该项目的中心目标，用于与传统表面硬化工艺相比，复合材料喷丸工艺的评估，也有助于实现对梯度复合材料的材料理解。研究了残余应力、微观组织、界面、静循环力学性能和硬化机制的热稳定性。

Graded composites with ceramic particulate reinforcement have a high application potential for lightweight, wear-resistant and cyclically loaded structural components. Especially a high thermal stability of the surface hardening mechanisms can be achieved by use of ceramic reinforcement particles. At the moment, cost-effective manufacturing processes which allow a surface reinforcement in highly stressed areas for improving the mechanical properties are not existent. A novel reinforcing technology of near-surface areas of components based on the micro-shot peening process will be developed which allows the defined inserting of dispersoids and is called composite peening. With respect to this reinforcing process a modified micro-shot peening process shall be used to analyse the process-relevant variables, such as temperature, jet pressure, working distance and shot agent diameter, on pure Aluminium, AlSi12Mg and an AlSiMg alloy. Likewise post-treatment procedures for a further improvement of the mechanical properties shall be adapted and evaluated. The characterization of the manufactured material states represents the central aim of the project and is used for the evaluation of the composite peening process in comparison to conventional surface hardening processes and also serves to achieve a material understanding of graded composites. Residual stresses, microstructure, interface as well as the static and cyclic mechanical properties and the thermal stability of the hardening mechanisms will be investigated.