## 1 Introduction  
The development of material properties deals, on the one hand, with the modification and, on the other hand, with the control of the macrostructure and the microstructure. This study focuses on the control of the microstructure of a pseudo-alloy. The microstructure of a metal is related not only to its mechanical properties, but also to its magnetic properties. If modification or damage occurs in the microstructure, this inevitably leads to deviating magnetic properties. This link should serve as a foundation for the use of ferromagnetic material properties as sensor properties [1]. Aluminium is weakly paramagnetic, but compared with ferromagnetic materials such as cobalt (Co), iron (Fe), and nickel (Ni), it can be defined as nonmagnetic. The aim of this study is to implant the nonmagnetic material Al with ferromagnetic particles iron (Fe), cobalt (Co), and nickel (Ni). In these materials, regions with identical magnetisation directions, which are called magnetic domains, are characteristic. Domains with different orientations are separated from each other by Bloch walls, see Figure 1a. The Bloch walls shift when a ferromagnetic material is exposed to an electromagnetic field. As a result of the shift, the Bloch walls interact with defects such as grain boundaries, dislocations, or segregations, as, from an energetic point of view, it is more attractive to attach to the irregularities. This phenomenon, known as pinning of the Bloch walls, is illustrated in Figure 1b. The interaction of the Bloch walls with defects causes them to move abruptly when the external applied magnetic field provides enough energy for the walls to tear themselves away from the defects. This results in a constant change between tearing loose and pinning on a microscopic level, which [PERSON] made audible in his experiment in 1919, after which the magnetic Barkhausen noise received its name. This method is used for micromagnetic material characterisation (MikroMach) to generate magnetic characteristic values of materials. Barkhausen noise analysis also offers the great advantage of being almost independent of the sensor head coupling [1; 2; 3; 4]. To characterise the material composite of Al with Fe, Co, and Ni, samples were generated by hot isostatic pressing (HIP). HIP enables the production of a homogeneous, compact material composite with isotropic material properties. Therefore, an almost \"ideal\" material behaviour can be realised for determination of the magnetic properties [7; 8]. The HIP process with pure Al has already been explained in some studies, as well as for Al-Fe [9; 10; 11; 12]. For nickel, the focus in the literature is on Ni superalloys and for Co on Co-chromium or Co-TiC alloys [13; 14; 15]. Otherwise, there are only reports on the melt-metallurgical production of all of the listed material composites [16; 17]. The focus of other studies is the complete transformation of the material composites, such as [11; 18], but not, as here, on the partial preservation of the particles to ensure ferromagnetic properties. The following study serves as a preliminary work for the implementation of a hybrid material made of Al with Co, Ni, and Fe, which should be realised by an additive manufacturing process, f.e., wire and arc additive manufacturing. Compared with traditional processes, additive manufacturing offers a high degree of freedom in the production of complex and hybrid materials, allowing components to be produced in a resource-efficient way [19; 20]. Consequently, the gas metal arc welding (GMAW) process was chosen for the welding implementation. In the literature, there are already studies on the connection of Al and Fe with laser welding, which are summarised in [21]. Al-Fe and Al-Ni can also be joined by magnetic pressure seam welding [22]. Cobalt is welded in compounds with other elements, for example laser welding of CoCr [23]. It is not obvious from the literature how to generate a material composite of Al-Ni and especially Al-Co by welding.