## 1 Introduction  
Permanent magnets play a significant role in transitioning from non-renewable fuels to sustainable energy sources; therefore, their economic importance across several technologies is increasing [1, 2, 3, 4]. The usage of rare-earth permanent magnets is growing, particularly in wind power production and electric vehicle technology, which necessitate high-performance magnets [5, 6, 7, 8]. Due to their favorable economics and strong magnetic characteristics, Nd-Fe-B permanent magnets are one of the most significant industrial materials used as magnetic field sources for motors, generators, and actuators [9, 10]. Their significant britteness makes producing intricate, tiny, and accurate magnets using traditional production techniques, such as machining, challenging [11, 12, 13, 14]. Within a global concern about reducing the dependency on the critical rare-earth elements, substituting Nd and Pr in the Nd-Fe-B type magnets with more abundant Ce and La elements is nowadays under consideration [15, 16]. Nevertheless, using these elements will reduce the intrinsic magnetic properties (saturation magnetization, anisotropy field, and Curie temperature) and, thus, the extrinsic ones (the remanence and the coercivity). However, this can be offset by re-designing some steps of the conventional routes for producing dense anisotropic magnets and optimizing the design of electrical machines. Advanced manufacturing processes, such as Metal Injection Molding (MIM), reduce the material required to produce a magnet and allow for complex shapes with an optimized magnetic architecture [17; 18]. They could offer substantial benefits by combining better system performances and material savings. Therefore, Ce-containing powders were used in this research, and a suitable MIM feedstock was developed. MIM can be a more cost-effective manufacturing approach for high production rates to manufacture Nd-Fe-B-based permanent magnets with complicated geometries, multiple or radial anisotropy, and good magnetic characteristics [19; 20]. Making magnets via MIM means having a binder system that performs different tasks at the four critical stages of the process: mixing, injection molding, debinding, and sintering [21; 22]. During mixing, the binder is compounded with alloy powder in an optimal ratio to create the feedstock in the initial step. In the course of injection molding, the binder system is a temporary medium to make the injection possible for the metal powder [23; 24]. For magnets, magnetic alignment is performed during the injection molding step to produce anisotropic magnets. The injected or green components are then successfully subjected to debinding to eliminate all binder components and sintering to provide superior mechanical and physical properties [25; 26]. After sintering, an appropriate annealing treatment is applied, and the magnets are magnetized to produce a permanent magnet. The binder system for the MIM process typically comprises a polymer as a backbone, waves as flow enhancers, and additives such as surfactants or lubricants to ensure powder dispersion [27]. Injection molding is one of the crucial stages in the MIM process because several flaws, including voids and powder-binder separation, can arise, especially when the feedstock is inhomogeneous [28]. These flaws may cause cracks in molded or sintered components. MIM feedbacks must conform to a specific rheological behavior to avoid these issues. Among the rheological properties, viscosity is one of the most critical rheological parameters that determine the suitability of a feedstock for a successful MIM process [29]. It is challenging to employ injection molding feedstocks with extremely high viscosities since they can lead to partially filled mold cavities; on the other hand, feedstocks with extremely low viscosities can result in binder-powder separation and have a high sensitivity to temperature, neither of which are desirable for MIM feedbacks [30].