Synthesis of Non-Equlibrium Alloys by Friction Stir Processes

搅拌摩擦焊接(FSW)是一种固相连接技术，通过局部塑化和机械搅拌连接接头的对接表面来产生粘接，由于材料在加工区的动态再结晶导致的细晶组织，所获得的连接性能可以达到非常高的质量。这种对微观结构的有利修改针对的是搅拌摩擦加工(FSP)。这种工艺变种的目的不是加入纯材料处理。FSP用于局部细化工件的显微组织。这两种搅拌摩擦技术(FSW和FSP)都有一个共同点，那就是通常不使用填充金属。然而，通过搅拌摩擦技术实现热机械合金化的可能性是绝对存在的。一些科学出版物表明，例如，通过FSP技术，可以在插入的添加剂和基材之间产生牢固的连接，甚至有时甚至是可验证的合金化。此外，作为准备工作的一部分，研究表明，通过在固态中形成金属间化合物相，基本可以实现搅拌摩擦焊焊缝与焊料的特定合金化。然而，所描述的结果主要是基于材料科学的调查，很少被归因于程序操作。因此，对合金成形过程及其影响变量的全面了解，以及通过技术程序控制这一过程的方法仍然缺乏。该项目的目的是了解摩擦搅拌技术作为生产非平衡合金或具有局部改性成分的材料的一种方法的可能应用。为此，一方面要加深对搅拌摩擦机械合金化过程中与工艺有关的要求的理解，另一方面要加深对冶金操作的理解。生产工程的研究将集中在所应用的填料材料的均匀分布和确定或产生合适的工艺温度。在材料科学方面，重点将放在合金化和所生产合金的性能的分析上。新获得的知识将最终导致一个耦合的过程和材料模型来描述合金的形成和控制机制。

Friction Stir Welding (FSW) is a solid-state joining technique in which the adhesive bonding is produced by a local plastification and mechanical stirring the abutting surfaces of the joining partners.The achieved joint properties can reach very high qualities due to the finegrained microstructure, which is caused by the dynamic recrystallization of the material in the process zone. This advantageous modification of the microstructure is targeted at Friction Stir Pro-cessing (FSP). Instead of joining a pure material treatment is the aim of this process variant. The FSP is used to refine the microstructure of workpieces locally. Both Friction Stir techniques (FSW and FSP) have in common, that usually no filler metal is used. However, the possibility of thermomechanical alloying by Friction Stir techniques is absolutely given. Several scientific publications indicate, that for example through the FSP technique solid connections and occasionally even a verifiable alloying between the inserted additives and the base material are producible. Furthermore, as part of the preparatory work, it was shown, that a specific alloying of FSW seam with a welding filler metal is basically possible by the formation of intermetallic phases in the solid state. However, the described results are mainly based on material science investigations and have rarely been attributed to procedural operations. Thus, a comprehensive knowledge of the alloy forming processes, their influencing variables and a way to control this process through technical procedures still lacks. The aim of the project is to gain understanding of the possible application of Friction Stir techniques as a method for the production of non-equilibrium alloys or of materials with locally modified composition. For this, a deepened understanding of the process related requirements on the one hand and on the other hand of the metallurgical operations during the mechanical alloying of metals by Friction Stir techniques will be investigated. The research of production engineering will focus on a homogeneous distribution of the applied filler material and determining or generating a suitable process temperature. Referring to material science the focus will be on the analysis of alloying and the properties of the produced alloys. The new acquired knowledge will finally lead to a coupled process and material model for describing the mechanism of alloy formation and controlling.