Process chains for co-extrusion and heat treatment of asymmetrical compounds made of alumini-um and titanium

新应用项目的目的是开发制造具有连续粘合增强元素的复合型材的工艺链，包括材料科学和生产技术之间的必要关系。根据研究和前期工作的现状，这些需要共同发展的关系可以缩小为以下几个方面：通过共挤压形成材料粘合为了避免夹紧和撕裂增强元件，摩擦接触仅限制在模具的区域。为此，在清洁和预热的条件下，刚性增强元件从外部送入捆仓，并从挤压铝型材中拖出。通过使用ECAP模具，可以实现侧向进料所需的挤压型材偏转，该模具也可以生产非对称复合型材。与前驱体项目相比，应通过用惰性气体完全吹扫的清洗和预热装置来实现无氧化物扩散层。因此，必须在考虑挤压参数、外部补强元件的表面条件及其预热条件的情况下，对用ECAP方法共挤压化合物有更深入的了解。由于复合型材的不对称性和不同的热膨胀系数，可以预期显著的尺寸和形状变化。关于挤压复合型材的畸变补偿方法的信息在文献中找不到。因此，为了找到合适的变形补偿方法，必须更深入地了解挤压和热处理过程中尺寸和形状变化的发展。第一个项目阶段的结果表明，结合强度在很大程度上取决于扩散形成的结合区。此外，作为两种材料中较弱的铝的强度也必须考虑在内。因此，热处理是调整最终粘结性能的重要工艺步骤。关于热处理过程中粘结性能建模的研究尚无定论。因此，根据热处理条件，必须深入了解键合区的演变和变化，从而能够对所产生的键合特性进行建模。

The aim of the new applied project is to develop process chains for manufacturing com-pound profiles with continuous bonded reinforcing elements, including the necessary relationships of materials science and production technology.Based on the state of research and preliminary work these relationships to be developed jointly can be narrowed as follows:1. Formation of a material bond by co-extrudingIn order to avoid clamping and tearing of the reinforcing element, the frictional contact is only re-stricted on the region of the die. For this, the rigid reinforcing element is fed in cleaned and pre-heated condition from outside into the bale chamber and dragged from the extruded aluminium profile. The required deflection of the extruded profile for lateral feeding can be achieved by using an ECAP die that also enables the production of asymmetric compound profiles. Compared to the precursor project an oxide-free diffusion layer shall be achieved by means of the cleaning and pre-heating device that is completely purged with inert gas.Thus, a deeper understanding of the co-extrusion of compounds by means of ECAP has to be developed in consideration of the pressing parameters as well as the surface conditions of the externally fed reinforcing elements and its pre-heating conditions.2. Development of the dimensional and shape changes along the process chainDue to the asymmetry of the compound profiles and the very different thermal expansion coeffi-cients significant dimensional and shape changes can be expected. Information about distortion compensation approaches for extruded compound profiles could not be found in the literature.Therefore, in order to find suitable distortion compensation approaches a deeper insight has to be gained regarding the development of the dimensional and shape changes during extrusion and heat treatment.3. Evolution of the bonding zone and bond properties during heat treatmentThe results of the first project phase show that the bond strength largely depends on the bonding zone caused by diffusion. Additionally, the strength of aluminium as the weaker of the two materials has to be considered as well. Therefore, the heat treatment is a significant process step for adjusting the final bond properties. Works, which deal with modelling of the bond properties during heat treatment, are not known.Hence, depending on the heat treatment conditions an indepth insight into the evolution and modi-fication of the bonding zone has to be gained that enables a modelling of the resulting bond properties.